Falsification HM5501 Lecture 4

October 15, 2017

Karl_PopperWhat we want is some criterion which will allow us to distinguish science from any other discourse. In other words what makes science, science, as opposed to religion? What is specific to the method of science? Our simplest response to this question is that science deals with facts that are objective (out there in some way) and that religion has to do with belief and is subjective. We might want to say, then, that science is true, and religion is not. When we looked at this simple definition, however, the less certain and clear it seemed. For the idea that science is made up of many observations of facts that are then converted into theories breaks down in the problem of induction, which, in its most succinct form, is the impossibility of leaping from a singular judgement to a universal one. No amount of logical finessing will get you from a particular to a universal judgement. This would seem to imply that science is no more objective than religion, and that a theory is as much a belief as any faith, though a particularly strong one when it comes to habits of the human mind.[1]

Moreover, it was also clear that the ‘inductionist’ picture of science was not accurate at all, since facts are not just littered throughout the world such that we pick them up and notice common characteristics from which we then construct some universal law, as though coming up with a scientific theory were no different from observing black crows and coming up with the statement ‘All crows are black’. On the contrary, we already come to facts with a pre-existing theory, which determines which facts we take as relevant or not (or even which fact we can see). As Ladyman explained, Newton did not find the law of gravity in Kepler’s data, he already had to have it in order to interpret the data (Ladyman 2002, pp.55–6).

This reversal of the relation between theory and facts, that theory is first and facts second, is the basis of the next philosophy of science that we shall look at, Popper’s theory of falsification, and indeed rose out of the insurmountable problems of ‘inductionism’. His argument is that we should give up induction as the basis of science, but such a rejection would not lead to irrationalism. Rather we substitute for induction, deduction. But did we not argue already in the first lecture that deduction could not be the basis of science, since deduction is merely tautological? Deductive logic tells us nothing new about the world, but only analyses what we already know, whereas science actually tells us something about nature that we didn’t know before.

Deduction does not work as a basis of science only if we move from the singular to the universal, but if we go from the universal back to the singular then deduction does work. Indeed, this move from the universal back to the singular is exactly, Popper argues, how science operates. We do not start with facts and then make laws, rather we start with laws and then we attempt to test them with facts. The logical point is that we can’t go from observations to theories, even if the observations themselves are true, but it is possible the other way around. We can go from theories then back to observational statements to show that the theory is false. Thus to use Chalmers example, if someone was to see a white raven outside the lecture room today, then this would prove deductively that the statement ‘All Ravens are black’ is false. Such deductive arguments are known as modus tollens, which take the form if P, then Q. ⌐Q, therefore ⌐P (Chalmers 1999, p.61).

When we look at the history of science, this seems exactly what happens. Take for the example, Eddington’s proof of Einstein’s theory that gravity bends light. If the theory was correct then a star that was beyond the sun should be displaced from the direction of the observer so that we could see it. Normally the light from the sun would mean that these starts would not be visible to us, but would be if the light of the sun was blocked. Eddington managed to measure just such a displacement with the eclipse of the sun in 1919. For Popper, the point of this story is that he could have proved otherwise. In other words, Einstein’s theory could have been falsified, if there had not been any displacement.

The real difference between science and religion or any other discourse is not the theories or hypotheses put forward, but how they are tested. Popper is adamant that science is creative as any other human discourse and that the origin of this creativity is outside any logical explanation. That someone comes up with such an idea at such a time cannot be logically deduced. Thus, it would require a complex explanation, comprising of psychology, history, and sociology, for example, of how Galileo or Einstein came up with their ideas, and why not someone else, or at different time and place, but what we do know that what makes these creations scientific, as opposed to anything else is that they can be falsified (this is the difference between context of discovery and context of justification). In the opposite case, it does not seem possible to falsify a religion logically. I can always find a reason to believe something. Think for example of the classic problem of evil in theology. How do I justify the existence of God with evil in the world? It is perfectly possible to find such a reason, as Leibniz did, that this is the ‘best of all possible worlds’, and it is just our lack of human understanding that prevents us from seeing it so.

Here we might need to know a little of the story of Popper’s life. When he was young he was a communist and of course Marxism was treated as a science. He says that one day in went on a march with his friends and they were attacked by the police and some of them were killed. He was so shaken by this incident that he had to speak about to his political leaders. They told him that these deaths were necessary for the political emancipation of the workers as was explained by scientific Marxism. But what then would falsify Marxism, for they did not seem to be any instance, including the death of his friends that could not be explained by it.[2]

This is precisely the difference between a science and a pseudo-science (religion is only a pseudo-science when it takes itself to be answering scientific questions, otherwise it is perfectly meaningful for Popper): a pseudo-science has the answer to everything and can never not be true, whereas a science does not have the answer to everything and can always be false. It is this that demarcates, to use Popper’s word, empirical science, from anything else, and it is a question of method, rather than logical form, by which he means the positivist obsession with the correlation of statements with aspects of reality. Metaphysics and religion are only pseudo sciences when they pretend to be sciences. If they do not, then there is nothing intrinsically wrong with them. They are certainly not meaningless which is just derogatory word, rather than having any useful philosophical sense.

If what makes a scientific theory scientific is falsification, what exactly makes a falsification? Can any falsification be scientific? Such a broad generalisation does not seem to be correct because just to falsify something would not make it a scientific theory. I could falsify physics, by quoting Genesis but no one would think I was being scientific. The answer here is intersubjective testability. One cannot conceive of how it would be possible to set up an experiment that would test my falsification of physics that claimed God had created the universe in the way that it is described in Genesis. One can imagine, however how it might be possible to test the falsification of Newtonian science through the prediction made by Einstein, which is entirely what the example from Eddington proves, and it is perfectly possible that other scientists could conceive of such an experiment, whether in principal or in practice.[3]

Could a theory always secure itself by simple adding an ad hoc modification every time a falsification was produced? Thus, to use Chalmers’s example, we could take the generalisation that all bread was nutritious to be falsified by the death of all the members of French village who ate bread. We could then qualify our theory by saying that all bread is nutritious except when it is eaten by these members of the French village and we could do this every time any falsification was discovered. Such ad hoc modification would destroy any progress in scientific discovery. How then can we distinguish between an authentic and inauthentic ad hoc modification (Chalmers 1999, p.75). In this example, the modification cannot be falsified, so it does not tell us anything new about the world. It in fact tells us less than the original theory that all bread nourishes. So, an authentic modification must be one that is also falsifiable. If we had said instead that all bread nourishes except one that is contaminated by certain fungus called Claviceps purpurea, then this would be an authentic ad hoc modification, since it could be tested and falsified, and thus does tell us something new about the world.

This distinction between authentic and inauthentic ad hoc modifications of scientific theories, however, tells us that we should not over-estimate falsifications of theories. When we look at the history of science we can see that ad hoc modifications can confirm rather than deny a theory. Take the case of the discovery of Neptune. Irregularities in the orbit of Uranus predicted that there must be another planet that had not be observed. Rather than reject Newton’s theory, scientists argued that a planet must exist that would explain it. Thus, the fact that Neptune was found in 1846 confirmed Newton’s theory rather than falsified it. Rather than seeing science as just a series of falsifications, which lead from theory to the next, Aristotle to Newton to Einstein, we should see it as the confirmation of bold conjectures and the falsification of cautious ones. For what difference does it make to science if one falsifies conjectures such as the universe is made of porridge or confirms a cautious one? But how then do we determine what makes a bold conjecture? The only answer to this must be background theories themselves, for only in relation to them could we know what would be bold or timid. The background knowledge is therefore the cautious conjecture (what we take to be correct) and the bold conjecture flies in the face of what everyone thinks is the case. We can see, then, what the real fundamental difference between the falsificationist and inductionist is. The first takes the history of science seriously, and the second has no conception of the history of science at all. There is no background knowledge. Rather facts are accumulated as though there were no context at all and science existed in the eternal present.

Is falsification immune to criticism then? The answer must be unfortunately not. The real problem is still the relation to the theory and the observation. All we can say deductively is that if there is O, then the falsity of T follows if the O is not given, but it tells us nothing about the standard of the evidence itself. What if the evidence is incorrect? Perhaps when person who said that the raven was white and no idea what white was. Perhaps the photograph of the white raven was created in Photoshop, and no such evidence exists. Popper does not have a better story about the correctness of evidence than the positivist.

Moreover, when we look at science, it does not take the simple form of ‘All swans are White’. Rather, sciences are made up of complex collection of universal statements which are interrelated to one another. Now if a prediction tells us the theory is false it tells is that one of the premises might be wrong but not which one or even that our own experience might be the problem. It might not the theory that is out, but the ‘test situation’ itself, because we cannot isolate the premise which allows us to falsify the theory (this is known as the Duhem/Quine thesis). So to use Ladyman’s example, if we were to try and predict the path of a comet, the law of gravity would not be sufficient, so if the predication were incorrect we would not know that it was the theory of gravity that was being falsified or something else (Ladyman 2002, pp.77–8). You cannot isolate hypotheses in science and refute one and others, because these different hypotheses fit together to make a whole.

Even if such an isolation were possible, falsification does not seem to capture what scientists do, for when we look at the history of science we do not find one great conjecture following another, but that scientists stick to their theories despite the fact that they can be falsified or they adopt a new hypothesis even though all the known evidence at the time should have killed them off at birth. This is what we find when we look at the detail of the eventual transition from the Aristotelian to the Copernican view of the world as Feyerabend and Kuhn describe it. It certainly was not the simple falsification of the one by the other. Science works, to some extent, because scientists are dogmatic and not open to falsification. If that is the case, how is it possible to differentiate, or demarcate, science from any other dogma? Will we not have to use different criteria, which are more pragmatic and historical than methodological?

Works Cited

Chalmers, A.F., 1999. What is this Thing Called Science?, St. Lucia, Qld.: University of Queensland.

Ladyman, J., 2002. Understanding Philosophy of Science, London; New York: Routledge.

Popper, K.R., 2002. Unended quest, London; New York: Routledge.

[1] When we look at science as a method this is a problem. We might ask, however, if we think of science as an activity, whether it is such a problem since science is not a straightforward process of induction.

[2] The source of this story can be found in Popper’s autobiography (Popper 2002, pp.30–8).

[3] Does this open Popper to a more pragmatic account of science than an epistemological one? For if testability is inter-subjective how are we to describe it? Popper appears to want to separate questions of method from question of practice, but later criticisms will in turn want to question this distinction by asking whether it is really the case, when we look at the history of science, that scientists really are committed to the principle of falsifiability. This will be part of Kuhn’s critique of Popper.


The Problem of Induction HM5501 Lecture 3

October 15, 2017

HumeThe justification of science appears at first glance to be the generalisation of experience. I heat metal x and see that it expands, I heat metal y and see that it expands, I heat metal z and see that it expands, and so on, such that it seems natural that I can claim that all metals expand when I heat them. When you hear then talk, then you would think that most scientists think this is what a scientific argument is, and most would also think this is what we might mean by scientific objectivity. There are, however, two questions we might ask of them. First of all, does the inductive method really produce knowledge in the way they think it does, and secondly even if it did is this how science itself operates in its own history? I actually think the second question is more important than the first. The first question is about scientific method, the second is more about what scientists actually do, and not what they say they do. It is a matter of pragmatics, rather than the logical definition of a method in the abstract.

Let us take the first question first, because it is the more traditional problem of induction, and has its canonical form in the argument of Hume. To understand his problem with induction we first of all need to understand, even if in the most basic way, his epistemology. For Hume, there are two kinds of propositions: relations of ideas, and matters of facts. In the first relation, the truth of our ideas is confined by our ideas alone. Thus if you understand the concept ‘bachelor’ you know the idea ‘unmarried man’ is contained within it. When it comes to matters of fact, however, we have to go beyond our concepts to experience. They tell us something new about the world and not just the ideas we already know. A matter of fact would be that Paris is the capital of France, or metals expand when heated. Of course when you know the idea then you know what is contained in it, but to obtain the idea you first of all have to get the knowledge. You only know that Paris is in France, if you have knowledge of basic geography. You only know that metals expand when heated, if you know metallurgy.

There can be false relations of ideas as there can be false matters of fact. Thus if you think that a whale is a fish, then you have made an error about a relation of ideas (you don’t know that a whale is a mammal), and if you think that Plato died in 399 BC, then you have made an error at the level of facts (Ladyman 2002, p.32). Relations of ideas can be proved true by deduction since the negation is a contraction. Basically relations of ideas are tautologies, you cannot assert that Peter is not a bachelor at the same time as asserting that he isn’t married as well, since being unmarried and being a bachelor are one the same thing. On the other hand, matters of fact cannot be proved by logic alone, but can only be derived from experience and their contradiction is not a fallacy. If I say that Everest is the tallest mountain on Earth, none of the terms have a logical relation to one another, so I could assume that there is taller mountain. I would have to experience the different tall mountains on Earth to know which one was tallest or not (Ladyman 2002, p.33). For this reason Hume was extremely sceptical about what one could claim to know deductively. All that one could claim are logical relations between concepts that we already known (whose origin anyway would be the senses). What we cannot claim is to produce new knowledge about the world simply through examining our concepts (as theology and metaphysics is wont to do in his opinion).[1]

These distinctions seem very straight forward and at first glance appear to back up the ‘inductivist’ view of science. The problem for Hume, however, is whether the idea that matters of fact could have the same necessary conclusions as relations of ideas, as the idea of expanding metals as a universal law implies. The key to this problem for Hume is whether I can assert that what happens in the past is a necessary certainty for what will happen in the future. I have experienced the fact that the sun rises every morning. Does this give me the right to say it will rise again tomorrow, when I haven’t actually experience this dawn yet? If it does rise then I will be certain, and in terms of the past, I know that it did rise, but now can I know that I will rise again tomorrow? It is perfectly possible, even if it were unexpected, that the sun might not rise.

Induction for Hume is based upon causal arguments. Our only knowledge of cause and effect is through experience itself because there is no logical reason why any causal relation should hold or not hold. I know matches cause fires, because I know that from experience, not because matches logically contain fire. Just as we can only infer future behaviour of the world from the actual experience of the world, then we can only understand the category of causality from experience. In other words without experience we would not have the concept of causality as a generality. If I always experience the dawn as the rising of the sun then I conjoin this events. If A always follows B, then I will say that A causes B. This because I believe that the future always follows the same path as the past. So that if A happens, then B will happen. Linked to conjunction is contiguity and precedence. Contiguity means that B follows A in time and space, and precedence is that the effect is always after the cause. (the flame is after the lighted match and not before). It is because of conjunction, contiguity, and precedence, that we feel that we have good reason to say that A causes B, or that the sun will rise tomorrow. Hume assertion, however, is that this can never be a necessary reason, as is suggested by generalisation of a universal law, however compelling I feel this causality to be.

Take the example of billiard balls, which seems the most basic relation of causality. The ball X hits the ball Y and causes it to move. But what do we mean by that? Do we mean that the ball X makes the ball Y move or that it produces its movement? We think there is a necessary connection between the two events. X moving and Y moving. What we experience is conjunction, contiguity and precedence, what we do not experience is some mysterious ‘necessary connection’. What we see is ball X and ball Y, what we do not see is some other third thing (like an invisible connection, indeed what we do not see is causality). What does it add to our explanation of the events, even if we were to add this mysterious cause. Wouldn’t the ball X and the ball Y just move in exactly the same way?

The point for Hume is just because two events have always in the past be conjoined, does not mean that we can be universally certain that they will always do so. The conclusion of inductive argument could be false but that would never make it invalid (indeed it might make it more interesting, if the sun did not rise the next day), but this is never the case with a deductive argument if the premises are true, then the conclusion is necessarily true. What underpins the inductive generalisation is the belief that nature is well ordered spatially and temporally, that what happens many times will happen again in the same way. But that is just an assumption. Why must the future always be the same as the past and it certainly is not a logical contradiction if it were not.

Now of course we make these kind of inferences all the time, and Hume accepts that. I probably would not be able to live if I really though the sun would not rise tomorrow every time I went to bed. But this uniformity is a result of our psychology (perhaps it is an evolutionary trait) rather than reason or logic. We find regularity in nature because our habitual associations of events, and not because these events are necessarily connected.[2]

There is no doubt that Hume’s problem is very profound and does make us look at induction more critically, but we might think that the idea that science itself is inductive in the simple way that ‘inductivism’ implies is too simplistic. So the problem is not with induction as such, but how we are using it. It is important to note that this is a very different critique from the methodological one. In the first case, we investigate the method of induction, and like Hume say that is flawed, or might even argue that Hume’s own account of induction is not a correct description of induction.[3] Whereas in the historical account of science, we are arguing whether the description of method is actually how scientists themselves work. One is a description of the content of scientific knowledge, the other is a description of the activity of scientists themselves. Do scientists really act the way that Hume’s example suggests they do? This is a completely different way of doing philosophy of science. For it does not first of all describe a method of doing science and then apply it to scientists, rather it examines what scientists do and from that derives the method. We shall see that this way of understanding science is going to be very important to Kuhn.

Why might we think that scientists do not use the inductive method in the way that induction has been described so far? Take the example of Newton’s Principia (Ladyman 2002, pp.55–6). Newton presents in this work the three laws of motion and the law of gravity. From these laws in explains natural phenomena like planetary motion. He says that he has inferred these laws through induction from observation. Now it is French philosopher of science Duhem that points out that there is a problem with Newton’s explanation. The data he is using is Kepler’s. His data proves that the planet will move in circles, whereas Newton’s in ellipses. This means that he could not have inferred gravity from Kepler’s data, rather he already the hypothesis of the law of gravity to interpret Kepler’s data. Even Kepler’s theory could not have be derived from observation, because he took his data from Brahe, but could only organise it by already assuming that planets moved in circles, a hypothesis he didn’t receive from data, but from the mystical Pythagorean tradition.

So there are two reasons why we might be sceptical of the simple inductive explanation of science. One is methodological through the problem of induction (though we might come up with a better inductive method to solve this), and the other is historical, that science does not work in the way that theory of induction describes. I think the latter is the more serious issue than the former. For in the end science is what scientists do, and not what philosophers might idealise that they do. If you like, the problem of induction is a problem for philosophers. It isn’t one for scientists. They work in a very different way indeed.

Works Cited

Ladyman, J., 2002. Understanding Philosophy of Science, London; New York: Routledge.


[1] A group of philosophers from the 20th century called logical positivists also liked this distinction, and differentiated mathematical and logical truths, on the one hand, and science on the other. Anything that didn’t fit this schema was said to be nonsense or meaningless. I am not sure that Hume would have gone that far.

[2] Kant’s argument against Hume is that causality is not merely a habit of the mind but a necessary part of our representation of the world. It would not make sense without it.

[3] This is what Ladyman does when he lists all the different ways in which we might counter Hume, the most telling being induction as the ‘best explanation’ (Ladyman 2002, pp.46–7).

Induction – Lecture 2

October 10, 2016

BaconLast week we spoke about the difference between science and religion. We said it could be conceptualised as one between belief and facts. The more, we investigated, however, what a fact is, the less certain we became of its status as a starting point for scientific investigation. Common sense might tell us that facts are just out there and we simply observe them and scientific theories are merely collections of these observations, but when we look at the history of science, however, it is clear that this is not how science works. What we take as facts are already determined by the way we understand and see the world, and our observations are equally shaped by this background conceptuality. In the next two lectures, we are going to investigate the problem of induction, which is probably the classic form of the philosophy of science, and we shall see that we’ll come up against the same barrier again. Moreover, the knowledge that science has of the world cannot itself be infallible, because of the very way that it interprets these facts. In this lecture, however, we’ll give a positive account of induction through Francis Bacon’s method in Novum Organum (1620).[1]

Ordinarily we might think that scientific theories are obtained from facts through observation and this is what makes it different from belief. But what does it exactly mean that theories are obtained or derived from facts? How do we get from the one to the other? What we mean here is something logical rather than temporal. We don’t just mean that first of all there is a collection of facts, and then a theory, as though facts were just pebbles on a beach that we pick up. A theory, on the contrary, is supposed to tell us something about these facts before we have even discovered them. It is about meaning and context, rather than just what comes first or second in a temporal order.

What then do we mean by derivation when we speak about logic? We don’t have to go into the complexities of logic here but just the basic form since all we are interested is how theories originate from facts. Logic is based upon deduction. Here is a valid deductive argument, which comes from Ladyman:

All human beings are mortal

Socrates is a human being

Socrates is mortal. (Ladyman, 2002, p. 19)

1 and 2 are the premises and 3 is the conclusion. You cannot deny the conclusion if you take the premises as true. We can change the premises slightly, however, as Ladyman writes, and the deduction would be wrong.

All human beings are animals

Bess is an animal

Therefore Bess is a human being (Ladyman 2002, p.19)

What is important here is that it’s the form of the argument itself that is wrong. The conclusion does not follow from the premises even if one accepts them. Bess could be any kind of animal. What is positive about deductive arguments is that they are truth preserving. That is, if the premises are true and the argument is valid, then the conclusion is. The problem is that the conclusion does not contain any more information than the premises. It does not tell you anything more about the world and surely this is what science does. Although science uses logic and mathematics, it does tell us something new about the phenomena we observe. If it did not, then there wouldn’t be different theories about the world.

From this is follows that if science is derived from facts then it cannot be done so logically, because logic cannot tell us whether a fact is true or not. If we know there are true facts then we can logically relate them together (logic is ‘truth preserving’), but it is only from experience whether we know they are true or not. Take for example the scientific law that metal expands when it heats. It does not matter how many times that I repeat this, as Chalmers argues, it does not logically follow (as is implied below) that all metals will expand when heated:

metal x expanded when it was heated

metal y expanded when it was heated

metal z expanded when it was heated

All metals expand when heated (Chalmers, 1999, p. 44)

If scientific theories don’t come from facts logically, then how are they derived? The answer must be through experience itself; that is to say, inductively. What do we mean by induction? First of all the difference between deductive and inductive arguments is that in the latter the conclusion always goes beyond what is contained in the premises, as the example above shows. I can never be certain that all metals will expand when heated, because this is precisely what I assert when I move from a singular instances (this metal expands when heated) to the universal judgement that all do so.

How then can I adjudicate between a bad and good inductive argument in the way that I did with deductive ones? It would seem, through common sense, that I might be able to justify my universal judgements if I go through a number of singular observations. In other words, I observe a large number of samples of metal to investigate whether they do expand or not, and if I observe in this large number that they do, then I would be justified in asserting ‘All metals expand when heated’. Thus the laws of induction would be

1) The number of observations should be large

2) They must be repeated under a wide range of conditions

3) There should be no exceptions.

It is precisely for this reason that English philosopher and scientist Francis Bacon can up with his ‘new method’.[2] First of all this method is negative. The point is that we should avoid falling into bad arguments rather than coming up with new deductive ones. Bacon’s method is rules about how to practice science by avoiding some of the worst errors. These errors he called ‘idols of the mind’: that we tend to see order and regularity in nature when there is none is the idol of the tribe; that our judgements and are shaped by our language and concepts rather than what we see is the idol of the marketplace; and finally that are views of nature can be distorted by our philosophical and metaphysical systems of thought is the idol of the theatre.[3] From this follows the positive content of Bacon’s method that we ought to make observations of nature that are free of these idols. It is from the mass of information gained through observation that we should make generalisations, rather than understanding our observations through generalisations, which he accuses the philosophers of doing. This he calls the ‘natural and experimental history’.

It is important to understand what Bacon meant by observation is not just looking at the world, but doing experiments, and it this emphasis on experiments that distinguishes the new method from the old Aristotelian one.[4] It is experiments that preserve the objectivity of observations. First of all, it allows them to be quantified and secondly that they can be repeated by others and thus tested as to their reliability. It is this data from experiments that are then put into tables. To use then example from Bacon of heat: first we have the table of Essence and Presence that lists those things that are directly part of the phenomena of heat; secondly, we have the list of Deviation and Absence, which lists those phenomena that are related to the first but have no heat; and then we have the list of Comparison, where features that have a quantity of heat are listed and quantified. The empirical method is one of elimination. Let us say I argue that the colour white is explanation of heat. Then I would check my tables and I would see that not all the phenomena that hot are white, or that some phenomena that are white are not hot and so on. White, then, could not be part of theory of heat. Through this process of elimination Bacon explained that heat was caused by the ‘extensive motion of parts’, which is not far from the modern kinetic theory of heat.

Bacon believed one can discover the forms that made what we observed possible, even though they were not directly perceivable. These forms where the direct physical cause of what we saw. This was the rejection of final causes, where natural phenomenon where viewed as purposive. The Aristotelian explanation, for example, that stones fall to the ground was because the earthly element sought to fall to the centre of the earth. Teleological explanations such as these are only suitable for human actions (since humans unlike stones do have desires) but not natural phenomena. The ubiquity of physical causes is the major different between new empirical science of the 17th century and the old science of Aristotle’s era that had dominated the explanation of nature for so long.

There are, however, problems with induction. First of all, what is the status of the non-observed forms that are the physical cause of what we observe. How can we make a leap from what is seen to what is not seen? It is possible to see how heat might be explained by Bacon’s method since in fact we can see the motion, but how would we go about explaining radiation? Also we see in science that there can be two competing forms that explain the same visible phenomena such as the two theories of light, for example. Bacon does have an answer for the last problem. He says that we ought to set up two competing experiments that would test what we observe and we could see which was the more successful. But this already demonstrates what we might doubt about Bacon’s new method. In this case are not the theories themselves determining the experiments and not what we observe? Bacon says that science is made from two pillars: observation and induction and that we ought to be able to observe nature without prejudice (the prejudices being the idols of the mind). This is perhaps what most people think that science is. We take many particular instances and then we generalise a law. Yet the problem is how we account for this mysterious leap from the particular to the universal. How many instances make a general law and if there is an exception does this mean that law is no longer a law?

There are, then, two problems with the principle of induction as Bacon describes it. One is that we might doubt that any observation is unprejudiced. This is not just in a negative sense as Bacon describes it, but also positively, that without a theory it is hard to know what one would observe in the first place. Secondly, we might worry about how it is possible to go from many observations to a general law. Just because X has happened many times before, how do we know we know that it will happen again? This problem of induction, as it is called, and was introduced by the Hume, and has for many made naïve ‘inductivism’ untenable. We shall investigate this problem in next week’s lecture.

Works Cited

Chalmers, A.F., 1999. What is this Thing Called Science? University of Queensland, St. Lucia, Qld.

Gaukroger, S., 2001. Francis Bacon and the Transformation of Early-Modern Philosophy. Cambridge University Press.

Harrison, P., 2007. Was there a Scientific Revolution? European Review 15, 445–457.

Ladyman, J., 2002. Understanding Philosophy of Science. Routledge, London; New York.

[1] Although Newton had not read Bacon’s work, his scientific method was widely seen as following his account of induction, and through the fame of the former, has become the ‘common sense’ view of science. For a general account of the importance of Bacon for the image of science, see (Gaukroger, 2001).

[2] See (Ladyman, 2002, pp. 22–5) for this summary of Bacon’s method.

[3] As we can see, what Bacon sees as idols, we might see as unavoidable necessities and this precisely prevents us from accepting the inductive explanation of science.

[4] On the importance of experiments to Bacon’s conception of science, and the subsequent transformation of science from a solitary to a communal affair, see (Harrison, 2007).

Realism and Anti-Realism in Philosophy of Science –Lecture 6

January 24, 2016

higgs-simulation-3In a previous lecture we looked at Kuhn’s idea of history of science as broken by different paradigms that are incommensurable. Aristotelianism, Newtonianism, and Einsteinism, mark revolutions in the history of science rather than a smooth flow of one epoch into another which will some day reach an ultimate Truth when we can all stop doing science because what our theories say and what is are exactly the same and there will be no exceptions. What Kuhn reminds us is that when we think about what science is, rather than taking the philosopher of science’s word for it, we should examine what scientists do. We will find that the philosophical version does not much look like the real history of science, rather they are idealisations in both sense of the word: an abstraction and a kind of wish fulfilment. Kuhn is not sceptical of science as such, but the philosophy of science. His book, The Structure of Scientific Revolutions, marks the death knell of a particular kind of philosophical history of science, so that it can be replaced by the proper history of science, whose object is what scientists actually do, rather than what philosophers think they might do. In other words, the new object of this history of science is ‘normal science’, in all its messiness and vagueness, rather than an idealised science that has never existed except in the minds of philosophers like Ayer or Popper.

At this point, however, we are going to make a little detour back to philosophy, and that is to the question which should have been bugging us from the very beginning, which is what exactly is science about, rather than what is the history of science. Early on we characterised the difference between religion and science as the difference between belief and facts. We said that science is about reality, that it makes true description of real things that happen in the world. In a word, it is objective. On the contrary, religion is subjective. It does not give us a true picture of the world, but offers us a moral compass through which we can live our lives. To confuse religion with science is to undermine the importance of religion rather than to give it more intellectual support. There is no conflict between science and religion, because they are completely different discourses. One tells you what something is, the other how you ought to live your life.[1]

But what do mean when we say that science is about reality? Aren’t we being a little simplistic when we do that? What is reality after all? Everyone knows the old paradox of whether a tree that falls down in a forest makes a sound or not if no one is there to hear it. Is reality what we perceive or is it more than that? I would say that it would be absurd to say that there would not be trees, stones or stars if there were no human beings. As though human beings were to vanish the universe would vanish with them. The universe does not have any meaning, however, except for the fact that it means something for some being or other in the universe. A stone is not a stone for a stone. It is only a stone for human beings who understand what it is to be a stone. We’ll come back to this at the end of the lecture.

Both Chalmers , Okasha, and Ladyman (perhaps because they all belong to what can be loosely called the analytic tradition) seem very reluctant to address these questions head on (as though they were too philosophical and could be avoided. I would say that it is their hidden philosophical assumptions which allow them to avoid these questions).[2] For them, on the contrary, the important distinction is between realism and anti-realism, rather than whether reality exists out there as such and what we might mean by reality as a whole. Chalmers simply dismisses the idea that reality being formed by language (what he calls global anti-realism), through a Tarskian theory of truth, which begs the questions, because such a theory already has a commitment to a certain view of language, and a certain view of reality, which remains unquestioned by Chalmers himself. Investigating this presupposition, however, would take us too far from the subject of this lecture itself.

What then is anti-realism and realism in science? First of all it is important to note that both theories accept the reality of the world. So it is important not to confuse either with a thorough going scepticism. The difference between them has to do with the status of scientific theories, on the one hand, and observable phenomenon on the other. A strong realist would argue that both observable phenomenon and theories are true descriptions of the world out there, whereas an strong anti-realist would say that only observable phenomenon are true, and theories are neither true of false. All these authors, as far as I can see, occupy a position between these two extremes.

The common sense view, I suppose, would take it that both theories and observable phenomenon are true, so we are going to approach this question from this point of view. None of us would think that observable phenomenon are not real, that when I see a donkey there isn’t a donkey out there (again I am not so sure that both Okasha and Chalmers skip over this supposed reality far too quickly, but let us leave them to have that truth for now). What isn’t so certain is that theories really point to something out there. This is because much of the basis of a scientific theories actually point to phenomenon that we cannot observe. If we cannot see something, then how can we say that it is part of the world? From what vantage point would we say that it is real? Of course, as Okasha points out, many sciences do have as their basis observable phenomenon, such as palaeontology whose objects are fossils, but modern physics does not (Okasha, 2002: 59). We cannot literally see inside of the atom. We only have theoretical pictures of what they look like, and we do not know if at that level the universe really looks like that at all.

The anti-realist is not saying that there is no difference between science and someone who thinks that the earth is balance on the back of a turtle. Rather theories only give us structures or the scaffolding in which we can observe phenomena through experimentation, but it is only this literally observable phenomenon which we can take to be true. The theory itself we cannot prove is real or not, because there is nothing there to see which we could demonstrate as real or not. The history of science itself seems to bear this out, because there have been false theories that have actually brought out true observable phenomena, so there does not seem to be an analogy between the truth of a theory and the truth of observable phenomena. The example that Chalmers gives is the history of optics, which is littered with what we now understand to be false theories of light, and yet which provided correct observable phenomena. Thus Newton believed that light was made up of particles, then Fresnel believed that light was a wave in a medium called ether, then Maxwell, believed that light waves were fluctuating electric and magnetic fields in ether, then in 20th century we got rid of the ether and the waves were entities in their own right, then finally the wave theory of light was supplemented by the particle theory of photons.

It seems to go against common sense, however, to say that theories are just fictions on which we hang our experimental results. When we look at the history of atomic theory it does appear that we are getting a progressive understanding of the structure of atom, and it would seem entirely bizarre that the theory would predict what we ought to see, and at the same time being entirely false. One way of getting around this is by arguing that the anti-realist is making a false distinction between what is observable and what is not observable, since though we cannot see inside the atom, we can detect the existence of atoms by ionisation when they are passed through a cloud chamber. The strict anti-realist, however would say that, all we know is real is the trails themselves, and we cannot not know whether the atoms are real or not, just as we should confuse the trail that a plane leaves in the sky with the plane itself. In other words, we have to make a distinction between direction observation and detection.

The fundamental issue here is whether we can make a complete separation between theories, on the one side, and facts on the other. This is the real issue, rather than whether facts are observable and theories not. In fact it is the anti-realist and not the realist who is committed to the separation. Both Okasha and Chalmers, though in different ways, would criticise this separation. Chalmers returns to whether the history of philosophy really does prove that theories which were once taken as true are shown to be false by the next one, and so on infinitum, so that we can never know whether are theories give us an accurate view of the world, by arguing that each new theory takes up some aspect of the previous one which gives us a more and more accurate picture of the phenomenon we are attempting to understand. Thus a true theory (unlike the turtle theory) captures some aspect of the truth of the world, if only a partial one, which is then improved by the subsequent one (does this conflict with the Kuhnian view of science, since it implies an accumulative image of science?). Okasha, on the other hand, will claim that the problems that the anti-realist claims would undermine the possibility of claiming theories to be true, could also rebound against what we would think were observable phenomena, and thus would destroy the basis of all science altogether, since we could only claim to know what we could see now in this moment, and not past events, since again they are only known by detection rather than direct observation (this would be mean that the anti-realist argument would be like Hume’s problem of induction).

As I said at the beginning, I find both Okasha’s and Chalmers discussion of realism unsatisfactory and indeed both of their chapters seems to end without any kind of resolution as though they had both been exhausted by the discussion. What I think is left unthought in their views is that the only way we could access reality is through science, and thus if we cannot, then we cannot access reality. To me the discussion of observable and unobservable phenomena is a red herring. Nothing has meaning unless it has meaning for us and that is true of both observable and unobservable phenomena, but the real issue is whether our reality is first of all something that we observe. Here I would turn to the philosophy of Heidegger, who would argue that it is prejudice of a very old metaphysics that our first relation to the world is one of perception, what he calls ‘present-to-hand’. What is true both for the realist and the anti-realist is that they take reality to mean ‘present to hand’. It is just that one thinks scientific theories are speaking about something present to hand and the other does not. The world for Heidegger, on the contrary is not something, present to hand, but ready to hand. The world is first of all something that we orientate ourselves in, rather than perceive.[3] This context can never be investigated as an object, because it is what objects make possible. Even science itself must have its origin in this cultural context or background. It is only because science as an activity means something to us that we can approach anything in the world as a scientific object, and not the other way around.

As Heidegger argues in Being and Time, Newton’s laws are only true because we exist. If we were no longer to exist, and the world in which these laws made sense were no longer to exist, then it would be absurd to still say that these laws were true. This does not mean that things do not exist separate from us, nor that truth is relative. Newton’s laws really say something about things, because these things only are, in the sense of ‘true’, through our existence. This truth would only be relative if we really thought that there was a truth of things beyond our existence that we did not know. Things are only because they are there for us, but this in no way means that any assertion is possible. This would be to confuse assertion and the condition of assertion. The truth of reality is dependent on our existence, but this does not mean that you or I can say anything we like about this existence. For you or I as individuals are just as much part of this existence as anything else is. To be a scientist is to already accept what this existence means (what the world of science means, of which Newton’s laws are an example), and to refuse this is no longer to be a scientist.

Works Cited

Van Fraassen, B. (2006). Weyl’s Paradox: The Distance between Structure and Perspective. In A. Berg-Hildebrand, & C. Shum (Eds.), Bas C. Van Fraassen: The Fortunes of Empiricism (pp. 13-34). Frankfurt: Ontos Verlag.

[1] It is a wholly other topic whether religion is the only discourse that can do this, but that does not undermine our distinction between it and science.

[2] Okasha, Samir, ‘Realism and Anti-Realism’ in Philosophy of Science: A Very Short Introduction, Oxford: OUP, 2002, 58-76. A. F. Chalmers, ‘Realism and Anti-Realism’ in What is this Thing Called Science?, third edition, Maidenhead: Open University Press, 1999, 226-46. Ladyman is more willing to discuss the philosophical issues in depth, but he does so from an analytic perspective. What is lacking in all these treatments is what I would call ‘ontological depth’, and I am going to turn to this in the next lecture which will look at some of the ideas of Heidegger.

[3] I think that this is what Fraassen is getting at when he says that a theory or model of reality is only useful when we locate ourselves within it, though I don’t think he is referring to Heidegger’s distinction here. (Van Fraassen, 2006, p. 31)

Heidegger and the Question of Technology – Lecture 3

April 9, 2015

Heidegger_4_(1960)_croppedRight at the end of The Dialogue of the Two Chief World Systems, Galileo makes a distinction between the ‘sensible world’ and ‘a world on paper’(Galilei & Finocchiaro 2008, p.201). He is arguing that the true authority for our scientific theories is not what is written in books but what we can observe with our senses. I already implied at the end of the lecture on Galileo that we should treat this opposition with a little bit of suspicion since he might be guilty of rhetorical exaggeration. First of all, it is clearly not the case that Aristotle, or those who followed him did not use their senses, but equally, Copernicus’s idea hypothesis of heliocentrism was precisely that, and not something that one would come to simply by using one’s senses. Indeed, Descartes is being more honest than Galileo in this regard. He freely admits that the theory of nature, which is at the heart of the new science, that nature is uniform, homogenous, material quantity that is calculable mathematically, and what we see is a secondary phenomenon, cannot be proved by our senses. The opposite is the case. The basic principles of science are what we approach nature with rather than derived from experience. For Descartes, theories do not follow facts, rather facts follow theories.

For Descartes ultimately, science, or the ideas of science, find their culmination in the existence of God. Without the absolute power of God nothing would exist, but equally the beneficence of God guarantees that the most coherent conception of nature (which for Descartes are precisely the laws of the new science and the concept of nature as an homogenous material quantity) must be true of nature itself, despite the fact that I can never experience this ultimate reality.

What happens, however, once we give up this divine assurance? Heidegger’s answer is that Descartes, and Galileo’s, theory of nature is in fact a projection upon nature. We like to think that science describes nature as it appears, but in fact it already pictures nature in a certain way so that it can become an object for science. In other words, there is a determinate way that nature is experience in science, which would be different from how nature appears in art, for example, or when I go for a walk in the wood. Why do we take the scientific model of nature to be the only true account of nature? Perhaps because we are unaware of the historical basis of science or take it to be the natural or common sense way of viewing the world, though if we investigate it in any detail would we see that it is anything but natural in this sense.

What the idea of God hides, then, is that science is the mathematical projection of nature. Galileo conceals this by saying that what science describes is ordinary sensible nature. Descartes knows this is not true, since modern science explains nature through unobservable phenomena, but he conceals the mathematical projection of nature in a different way, by claiming, through the idea of God, that this is what nature is really, even though we cannot experience it.

The key difference between modern and ancient science is not that one is based on experience and experiment and the other is not (as Galileo polemically presents it), but that modern science is mathematical. Numbers are not found in things, nor are things numbers. What is mathematical has to be brought to nature, but for nature to be brought under mathematics it already has to be understood in a certain way. Mathematics provides the certainty (what Descartes thinks of as self-evident truths), but we must already think of nature as something that one could be certain about in the first place.

To think of nature as something certain is to think of it as homogenous. It is because Descartes already conceives of nature as extension (the corpuscular theory of matter) that it is mathematical. It is not because it is mathematical that he thinks of it as extension. Descartes claims that this idea has its validity in the idea of God. Heidegger would argue that this theory of nature is a projection, however useful it might be, of the scientist himself. This does not mean that what science describes is not real, as though its objects were ghosts, but that science never relates to nature empty handed. It only encounters reality within certain limitations. As we shall see when we look at the Question Concerning Technology later on, science sets up the object in advance.

This is why Heidegger will claim that the experiment is crucial to understanding modern science. Again this does not mean that there were no experiments before modern science, but that experiment was not crucial. What is important about the experiment is that it always sets nature up in a limited way. It constrains nature within the limits of the hypothesis that the experiment is meant to test. This is why it cannot be true, even when Galileo said it, that modern science is based simply on observation and experience, for the experiment precisely bypasses our ordinary perception of the world. It is clear, therefore, that the story of Galileo and the tower could only have been a myth. For in terms of the real world, which is not limited by the abstraction of the experiment, observing two balls hitting the ground at the same time is nearly impossible. What Galileo in fact did was, to demonstrate that a heavier object would not fall faster than a lighter one, was to release different balls from a ramp.

To say that the experiment sets up nature in a determinate manner, does not mean that the phenomena observed (the balls accelerating down the ramp) are false, or the theory of free fall is a fiction, but that nature here is experienced in a limited manner. The mistake is to think that the scientific explanation is a description of nature as it is. Heidegger would argue that this is not a scientific explanation but a metaphysical one, and this is why Descartes has to justify it with the existence of God. Once we give up such an idea, then we can see what science must be, which is a projection.

There is then no such as disinterested observation. This is not a criticism of science as being unscientific. Science is scientific because it is already an interested observation. It observes nature through a hypothesis which it then tests through an experiment. This relation between interested observation and experiment, however, is dependent on viewing nature as a whole as something calculable. This is what is common between Galileo, Newton, and Einstein, even though they have very different theories of nature.[1] Science already projects nature as quantifiable and for this reason it measures it. Experiments are only possible as tests of hypothesis because we already assume that nature is something that is measurable. The scientist shrinks the world so that it fits the experiment. But the world already is before we understand it as something measurable. The colour of the leaf already is before it is a wave of light that can be quantified. This does not mean that the quantity is not real for Heidegger, but he will ask us to consider whether the being of the leaf is reducible only to this quantification.

What science cannot do is get behind its own projection. If it were to do so, then it would cease being scientific. A scientist does not ask about the reality of the objects that it considers unless the science itself comes into crisis. I must accept the theoretical reality of the objects I study in order to test the hypothesis. If I were to do so, then I would never begin. Descartes, therefore, has take it for granted that the nature really is nothing but matter in motion, even though no such thing can be observed. What is interesting, historically speaking, is that unlike Galileo, perhaps because he is more philosophical, the projective nature of this theory is more visible to us because of the obvious artifice of the existence of God. However, generally speaking, all science is projection, and more so, when it claims just to be describing things as they really are. Just as much as Descartes metaphysical assumptions predetermine what nature is for him, then so too does the most extreme empiricist.

Although Heidegger is not criticising science as such, since modern science can only function as the limitation of nature by the experiment, what does worry him is the view that science is the only true explanation of anything that we experience and that our world is the very same as the representation of nature in science. Today, like the ancients would have looked for answers philosophy, or the medieval in religion, we now think that all answers are to be found in science. Science is now the ‘theory of everything’, and this everything also includes us.

Why does Heidegger think that such a conception of science, which has the same status as a religion, has hidden dangers? This is because concomitant with the view that nature is only something that is calculable or measurable is the conviction that it is something to be used up by us. Science, then, is not free of political and ethical interests in the broadest sense. This is what Heidegger means when he says that modern science and the essence of technology are inseparable.

The essence of technology and technological things are not the same, just as the tree and the essence of the tree are not the same, otherwise every tree would be identical to a particular tree. What we want to capture is the generality of the tree (Heidegger 1977). When we ask about the essence of something, then we are asking what it means to be that thing that it is. What then is general to technology. Heidegger says that we can think of technology in two ways: as a means to an end and as a human activity. Thus I use a mobile phone to text someone, and texting is something that human beings do. This Heidegger says is an instrumental way of thinking about technology and he does not disagree with this definition. He does not think, however, that it goes far enough. We use something to bring something else about. So we use a kettle to boil water and so on. At heart of instrumentality, therefore, is causality.

What has the history of philosophy to tell us about causality? The ancient, and the medieval, thought of causality in terms of 4 kinds of causality: material, formal, end, and, efficiency. The material cause of something is the matter from which it made, the formal cause of something is its design or plan, the end or telos, is the purpose or function of something, and finally the efficient cause is what brings it about. To explain the cause of something is to explain why something exists. Heidegger uses the example of the silver chalice. The material cause would be the silver it is made from, the formal cause would be the design the craftsman or woman works with, the end or telos, would be its function in some kind of ritual, and the efficient cause would be the work of the person themselves who hammers the metal and heats the fire. But even here, Heidegger suggests, we haven’t got to the deepest level, because why is their causality at all and why only four causes? The ancients and the medieval did not think of causality in the way we did as simply bringing something about, as the match brings about the fire, but being responsible for something. In each case the silver chalice is indebted to the causes. Without these 4 causes the silver chalice would not exist at all.

What is meant by responsibility here, Heidegger says, should not be thought of in the modern way, in terms of morality or ethics, as when we say someone is guilty of crime. The four causes are responsible because they make the silver chalice present. Without them it would not lie there before us, and we would not be able to hold it in our hands. Another way that Heidegger describes this is as ‘occasioning’. The four cause are the occasion of the chalice to be at all.

The way in which ancient philosophy through of this making present was through poiesis (where the English poetry comes from). It is not just poetry or handicraft that brings things into existence, but nature itself. Nature is the occasioning of things, as the apple tree is the occasion of the apple blossom. The craftswoman or man brings forth the silver chalice by making it present, as the apple tree brings forth the blossom by making it present. Something is made present that did not exist before. This making present Heidegger calls revelation or unconcealment, and is how the ancients experience truth.

The essence of technology is also a form of revealing or unconcealment, but it reveals nature in a very different way than poiesis. What Heidegger is emphasising is before technology is instrumental it revelatory. It reveals nature in a certain and determinate way. Rather than poiesis it is the ‘challenging forth of nature’ in which nature is something we use up as a store of energy. Such a way of revealing nature, Heidegger argues, is already hidden in the projection of modern science, which also only views nature as energy. When nature is viewed in this way it becomes a ‘standing reserve’. The river is no longer a course that flows through a valley, but a energy reserve to be used by hydroelectricity. The wood is only experience as a resource to produce cellulose or other industrial products. In the same way, human beings themselves are only seen as ‘standing reserves’ to be used up, such that nowadays it is quite common to hear people talking about human resources, as though there were nothing extraordinary about this.

The particular way in which nature reveals itself to us as something that we determine as standing reserve, Heidegger calls ‘enframing’ (Gestell). He is using this word in an original way. Normally, this word just means a ‘frame’, like in a picture frame. It sounds strange to use an ordinary word in this way, but no stranger than when Plato first used the word ‘idea’, which now sounds completely normal to us. What he means by ‘enframing’ is that nature as a totality must already be experienced by us in a certain way such that we experience both what we encounter in the world, and ourselves, as nothing but standing reserves. In the enframing, nature is reduced to calculation and manipulability. We can see therefore that modern science is at the heart of this process, and why we necessarily think, just as the medieval thought that everything was to be found in God, that science can answer every question. This does not mean that science creates the world around us. It means that since we only experience nature as calculable and manipulable, that science becomes the dominate world picture. This is not because a committee of scientists have decided that we should think like this, but this is generally how we experience nature as such, just as the medieval experienced everything through God, and no more decided this, than we decided our epoch.

Does not mean that Heidegger is anti-science? I think this would be a complete misunderstanding of his argument. Heidegger does not think that one can replace science by philosophy or another way of thinking (religion or spirituality or whatever way you might want to characterise it). On the contrary science only works because it limits nature to a sharply defined model that can be tested by an experiment. Heidegger’s worry is when we confuse this necessary limitation with the totality of nature and even more so when we think of ourselves in this way. But what is true of science is also true of religion in the medieval age or philosophy in the ancient one. What such an inflation of science conceals (that science describes nature as it is), is the political and ethical dimension of scientific and technological world view, where nature becomes only something that is to be consumed and used up. In the age of climate change and ecological catastrophes we might wonder whether such a relation hides a danger we have failed to foresee.


Galilei, G. & Finocchiaro, M.A., 2008. The essential Galileo, Indianapolis, Ind.: Hackett Pub. Co.

Heidegger, M., 1977. The question concerning technology, and other essays, New York: Harper & Row.

[1] This is the great difference between Heidegger and Kuhn. Even though like Kuhn, Heidegger will also differentiate Aristotelian and Newtonian conceptions of reality (he does not think quantum physics is a decisive difference), nonetheless between these different epochs is the same principle of the intelligibility and calculability of nature.

Descartes and the New Metaphysics – Lecture 2

March 22, 2015

800px-Frans_Hals_-_Portret_van_René_DescartesIf Galileo is the name that stands for the emergence of a new science and a new way of looking at the world, then Descartes is the one who grounds it in a new metaphysics.[1] For the scientist, who is dismissive of the need for philosophy, since for her it is only important if her model works, this is of no importance, but in the history of philosophy, he institutes a whole new way of thinking that all subsequent philosophy has to answer to.

One of the difficulties of reading Descartes, at least if you don’t read him in too much detail, and jump over the things he says that seem anachronistic, their main ideas have become such a part of our philosophical culture, indeed our culture as a whole (who has not heard of the famous cogito ego sum), that we can just read him without really making any attempt to understand. Moreover, the apparent ease of our interpretation means we can even think that we can easily dismiss these arguments, because everyone knows them and they hardly require any thought whatsoever. This is especially the case when we come to his famous proof of the existence of God, which we can dismiss with great ease if we are not aware of what problem it answers. Indeed the problem is more interesting than the question.

The simplicity of this reading has more to do with our ignorance, however, rather than our deep understanding. It is because we are unaware of the context of Descartes’ argument, why he wrote what he did, and especially their revolutionary nature, that we can easily be misled as to their depth and originality. The most important element of this context is the rise of the new sciences in the 16th and 17th century. Before he saw himself as a philosopher, Descartes viewed himself (if these different functions were really as separable to him and his contemporaries, as they might be to us), as a scientist and a mathematician. He wrote a philosophy as a defence of the new science, and the importance of the mathematical method, rather than just a work of philosophy in itself.

If we are going to understand how revolutionary the new science was, and why Descartes believed it required a different metaphysics to support it, then we have to recognise, if however succinctly and briefly, that metaphysics it rejected, which was Aristotelianism. Aristotle’s understanding of nature was the dominant picture of reality. The problem of dislodging this picture was not just that the new science rejected it, but that its hold on people’s imaginations was so prevalent and dominant. This is because Aristotle’s philosophy is the philosophy of common sense. It describes what we see around us, and thus to reject it is to reject everything we know around us. We can see why Descartes’ method is sceptical, because before he can reinstitute the new science on a secure ground, he must first of all get us to reject what we ordinarily take to be knowledge of the world. It is not enough to reform our current views; we have to reject them completely.

Such a revolutionary change, one we are still living with, is obvious in the famous rejection of the geostatic universe for a heliocentric one, but it is perhaps a more ordinary example that might make it clearer for us exactly what is at stake here. Let us compare, therefore, an Aristotelian account of vision from a Cartesian one (Hatfield 2014, pp.291–4). We today might be very blasé about Descartes’ mechanical explanation of colour, because we take for granted the physiological explanation of colour (colour is nothing but the interaction of the spectrum of light with the retina), but it would have sounded strange to his contemporaries. In the Aristotelian conception of sensation, my perception of external objects is caused by the real qualities of those objects. Thus if I see a red rose then my perception of ‘red’ is caused by the red qualities of that rose. The red exists in the rose, travels to my eye, and thereby causes my sensation of red. As we can see, this seems to be a very common sense view of what happens when we see things (and there are probably people who still think that this is what it means to physically ‘see’ the colour red).

For Descartes, on the contrary, there are no ‘red’ things as such. On the contrary, for Descartes, nature is nothing but matter in motion. Matter is corpuscular (infinitely divisible particles). The quality of red in the object, therefore, and its interaction with the eye, can be explained by the shape, size and motion of these particles. Colour is caused by the surface of the object I am looking at, which refracts light particles that interact with the eye. Descartes is not denying that we see red, but that red cannot be explained by a real quality called red. Rather the phenomenon ‘red’ requires a deeper explanation that can only be provided scientifically through the kind of mechanical model that Descartes describes

Although there are specific problems with Descartes’ explanation of colour, which will wait for the modern developments in optics, we can see that we are in two totally different scientific worlds. Fundamentally for Aristotle, everything that exists is explained through form and matter. It is the form of something that explains what it is. Thus to understand what it a tree is one has to understand the ‘form’ tree. If we are looking at an oak tree, then the form would be contained in the acorn. This is true, just as much for animate as well as inanimate things. So to explain the sun, we also have to understand the form of the sun, as well as its material existence (which for Aristotle was the four elements, plus the mysterious fifth one, aether). For Descartes, there is only a material explanation of nature. If one wants to understand the sun, then one needs to understand the nuclear fusion of hydrogen to helium. Moreover, these material laws are the same for all objects in nature and the whole of nature itself. The explanation of our sun would be the same as for all suns in the universe, and these explanations would be would be the same for everything that exists (that is, matter in motion, which can be mathematical defined).

The different physics of Aristotle and Descartes means that they have completely different metaphysics. The basis of the universe for Aristotle is individual substances. Because matter is not sufficient to explain what it is to be something, there cannot be a material explanation of nature. Each thing is an individual substance, which is the specific conjunction of form and matter, whether we are speaking of a tree or animal, me or you, the sun and the other stars. For Descartes, there is only one thing that exists and that is matter in motion, and every individual thing we see is only a property or a mode of this one material substance. Things differ only because matter differs (there is a difference is shape, size and motion of particles), not because there is an extrinsic difference between them. We can see in Aristotle’s metaphysics, that we need an explanation for each thing, whereas for Descartes, we only need a few simple laws of motion (three), in order to explain everything that we see, and that these simple laws of motion, since they have to only to do with shape, size and motion, can be explained quantitatively (that is mathematically) other than qualitatively in the Aristotelian system.

Only now with this scientific background, can we really begin to understand the Meditations. Descartes’ scepticism, at the beginning, then, is not merely an amusing thought experiment, which will later become the plot of the film Matrix, but presupposes the fundamental break that modern science has taken with the common sense perception of the world. For the hypothesis that nature is matter in motion is precisely that a hypothesis, which one can quite literally not see, and thus what I see cannot itself be true. Thus, the task for Descartes is not to destroy our knowledge of the world, but to rebuild it, but where the foundations will be more secure, no longer resting on our fallible senses, but reliable understanding and reason. Scepticism is not employed for its own sake, or even to make philosophy impossible, but on the contrary, to make our knowledge of the world even more certain, by showing that sceptical arguments can be defeated if our metaphysics is robust enough.

It is for this reason why Descartes takes his doubt much further than classical scepticism. We should not only doubt our senses, for we know that they tell us lies about the world (is that pencil really bent that I see in the glass of water), but also the world of mathematics and even the status of reality itself. How do I know that this is not all a dream, since my dreams have been as vivid as my perception of the world right now, and why it is not possible that a malicious demon hasn’t put into my head the idea that 4+4 = 8, when it really is 9?. Now all these sound a bit excessive if we don’t know the scientific context of these doubts. If the truth of reality is in fact mathematical, then the question Descartes is really asking is how I know that this mathematical reality is real, when there is nothing in my ordinary experience that would verify it.

If I can doubt everything in reality, even that my mathematical ideas are a true representation of what is real, then there is one thing, Descartes argues, that I cannot doubt, and that is I am thinking. For even if I doubt everything, there is one thing I cannot doubt and that is in the very act of doubting. What is important at this point in Descartes’ argument is not to confuse the status of the ‘I’ in the statement ‘I think therefore I am’. This I is not me as physical being. The ‘I’ that stands before you now, the ‘I’ that is writing this lecture on the computer. My physical reality is just as doubtful as the reality of the rest of physical nature. Also this ‘I’ only exists in the very moment of thinking. Only in the very act of thinking can the ‘I’ be said to exist, because it is self-refuting to argue otherwise. Even if I say, ‘I do not exist’, it is I who am thinking this, and so must exist in the moment I think it.

Though the cogito is very limited in one sense, it also includes a lot more than one might first assume. First of all Descartes includes all acts of consciousness, such remembering, desires, and most importantly for us, perceiving. Thus when I desire something, I exist in the moment of desiring, when I remember something I exist in the moment of remembering it, and when I perceive something, I exist in the moment of perceiving it. Of course, following from radical doubt, I don’t know whether what I perceive is the same as what is in reality (it really could be all a dream, or mathematical code as in the film Matrix), but I cannot doubt that I am perceiving the chair. Secondly, and this is going to be very important when we come to look at the wax, the content of what I think, desire, remember and perceive is also real Again, it is not real, as in ‘out there’, but real in my mind. So when, I am thinking, remembering, desiring, perceiving a chair, I really am thinking, remember, desiring, perceiving a chair, even though I don’t know whether a chair really exists.

What is going here, which is very important for understanding Descartes’ metaphysics, is that he is totally changing our idea of truth. Normally when we think of truth (and it should not surprise us, when we think of what we said about science above, that this too has a long Aristotelian heritage), we think of it as adequation. That is, we think that truth is about how we speak about the external world. When I say to you ‘There is chair’, you take this statement to be true, because there is a chair in the real world that corresponds to the statement. Now Descartes’ cannot appeal to this notion of truth, because at the moment of the status of the real world has been bracketed (I don’t know whether the world is true or not). He therefore replaces the truth as adequation, with truth as coherence. An idea is true because it is clear and distinct in my mind. The cogito is therefore a measure of what it is to be true since is self-evident that to have a thought there must be an ‘I’ that thinks it. But we can also say that the idea of triangle as a three sided figure is true, whereas the idea of square circle is not. Not because there are no square circle in the world, but because the idea itself does not make sense, since it is incoherent.

When we come to the example of the wax in the third mediation, therefore, we can become completely confused if we think Descartes is talking about the external perception of the wax, because this is precisely what he has given up (we don’t know what the real wax is, because we don’t even know if reality is real). What he is describing is our idea of the wax, how the wax appears to us, even if we don’t whether the wax is real or not. His first description, then, is how the idea of wax appears to us when we take the wax as something we perceive, but perception means here, perception as an action of thought (I am thinking about how the wax is perceived by me), and not perception as the sensation of an external object that I take to exist really outside of me and which effects my sense and which I then think of as was (our example of real qualities and the red flower above). If we were to take that Descartes was doing the latter, then we would be confusing him with Aristotelian account of perception.

What then do I think I perceive when I think that the idea of wax is sensation? I have a list of properties that describe the wax. It smells of flowers; it tastes of honey; it makes a sound when you tap it; it is hard and cold to the touch; and it is white and the shape of a cube. Doesn’t this, then, tell us exactly what the wax is. Why would we need to know anymore? We remember, though that Descartes is sitting in a warm room (it tells us at the beginning of the Meditations). With the heat of the room, all the properties of the wax change: there is no fragrance of flowers; no sweetness of honey; no sound when a hit it; it is not hard and cold; it is no longer white and shaped like a cup. How, therefore, can the sense tell us what the wax is, since now it is completely change. The idea of the wax under the thought of perception is a completely confused idea. However, even though I know the wax has completely changed, it is nonetheless the same piece of wax that remained the same throughout this transformation. What is this wax? It can’t be the list of properties of the sensation because these are completely different. It must be what remains when we strip away all these properties that have changed in our idea of the wax itself. What is it that remains? It is the idea of the body in general as ‘something extended, flexible and changeable’. [AT VII, 30] Although I cannot experience this body, since it would have innumerable shapes that I cannot imagine, I nonetheless can think it, and the idea of this body is less confused and incoherent understanding of the wax in general, than what is present by the idea of sensation. Going back to Descartes’ definition of truth, it is, therefore more true.

At this point we haven’t got outside the cogito itself. I can say that the idea of extension as the correct understanding of bodies, rather than their real qualities, might make more sense, but it does not mean that the what the wax is in the real world is anything like that at all. At this stage, extension (that matter is extended in three dimensions) as the explanation of all the phenomena we see, including the secondary phenomena of the senses, is merely a hypothesis. To prove that nature in itself is like that, we need to get outside of our minds. But how are going to do that? Through the proof of the existence of God, because the idea of God is a very strange idea, and necessitates the actual existence of the content of the idea, in the way that no other idea I have does.

Descartes is not the first philosopher to use the ontological proof for the existence of God, but it does have a particular form in his philosophy, so it is worth going into it in a little more detail. Also, we need to remember what kind of work the proof is doing. Descartes is not proving the existence of God because he lacks faith. He already believes in God. He does not need a proof. We are speaking here of a philosophical concept of God and not a religious one (although as we shall see with Spinoza’s criticism of Descartes, he might sneak a theological notion within this concept). The concept of God is solving a philosophical problem for Descartes, how do we know that are scientific hypothesis that we cannot see with our senses, is actually telling us the truth about the world, and not a crisis of faith.

One of the problems for the modern reader following Descartes proof is that he uses Scholastic terminology that they might not know.[2] Let us briefly explain this jargon before we look at the argument itself. When it comes to ideas in our minds, Descartes makes three important distinctions: objective reality, formal reality and eminent reality. The objective idea of the triangle is the idea of the triangle insofar as it represents a thing. The objective reality is not the thing represented, but the representation. One of the best ways to think of this is in terms of the operation of an image, though we should be careful here not thinking that Descartes thought that all representation were images. Thus when we say that a picture is a picture of something we can distinguish between what the picture is and what the picture represents. In the case of a picture of a tree for example, we can distinguish between the picture and the tree that is represented in the picture.

What is much more difficult is the idea of formal reality in Descartes. It is much more difficult because Descartes himself seems to be confused about it. We could interpret formal reality to be the actual existence of the thing that is represented in the idea. But this would admit the existence of external things, whereas we are only talking about the nature of ideas. Formal reality is the part of the definition of the idea and not the description of a thing. Many misunderstandings of Descartes have to do with confusing the formal reality of the idea with the reality of a thing. On the contrary, the formal reality of the idea describes the status of the idea itself. Whatever idea we speak of and whatever this idea might represent, the idea itself exists. Again if we go back to our picture example, being mindful that ideas are not pictures for Descartes, so that this is only an analogy, then we can make a distinction between the picture, on the one hand, and what the picture represents on the other. Now the picture, on this analogy, is the formal idea. That is to say idea of the tree itself, and not the tree that is represented in the idea.

Now for Descartes ideas themselves and not just what they represent in the idea, have degrees of reality. The best way to understand what Descartes means by ‘degrees of reality’ here is degree of perfection, otherwise again you are going to get confused and think that he is speaking about real external things. Now for Descartes it is possible to say that some ideas, formally speaking are more perfect than other’s. The idea itself is more perfect and not just what is represented in the idea (though it is true to say that when we are speaking about perfection these two are connected).. It is the idea itself that is more perfect, that is to say its formal reality, and not just what is represented in the idea, that is to say its objective reality. The idea of God does not just have more objective reality than the idea of frog; rather it has more formal reality than any other idea (Deleuze 1978). The idea of God, therefore, for Descartes, has eminent reality. Of course the immediate question we need to ask is why is the idea of God more perfect than any other idea? But before we get to this question we need to think about how Descartes explains the relation between objective and formal reality, for this is the basis of the proof of the existence of God

This relation is essentially causal for Descartes. That is to say that the formal idea is the cause of the objective idea. We might put it this way. In the absence of the idea of the frog, they would be no ‘frog’ as an object of the idea. This means for Descartes that the idea of the frog, it formal reality, is the cause of the objective reality of the frog. It is not just the causality of ideas that we need to be aware of, but also, as we have already seen, that reality means for Descartes ‘degrees of perfection’. The proof for the existence of God is a combination of causality and perfection. Thus the formal reality not only causes the objective reality to exist, but also the degree of perfection that this idea has. Descartes regards it as a fundamental axiom that more cannot come from less. If the formal reality is the cause of the objective reality, then there must be as much reality in the formal reality as there is in the objective reality. We need to be very careful that we are speaking about ideas and not objects, and the best way to think about it is again in terms of a picture. Descartes’ argument is that a picture will have more reality than any other one the more reality that the object of the picture has. Thus to use Bernard William’s example: a picture of a pile of sticks will have less reality than a picture of a complex machine, precisely because the complex machine, as an objective reality, has more reality than a pile of sticks (Williams 2005, p.124). The best way to think of the relation between objective and formal relations, when it comes causality and perfection, is therefore backwards. From the complexity of the object of thought we go back to the complexity of the idea which is the origin of this thought.

The question, then, is how I get from this relation between formal and objective reality of ideas to the proof of the existence of God. Again we need to remember that this is a causal relation for Descartes. The idea must have as much reality, perfection or complexity, as the object that it represents. In Descartes language, it contains formally as much reality as the object contains objectively. But this does not present it having more reality than the object it represents. In this instance, Descartes says it contains eminently what the object of thought only contains formally. But how does this further distinction get us any closer to the idea of God? Descartes asks whether it is possible that there is one idea that contains formally what I cannot be the cause of objectively; that is to say, whether there is an idea whose objectively reality, whose object of thought cannot have its origin in me.

Thus if I look at all the content of my ideas, I can see that they can all have their origin in me, but the objective reality of the formal idea of God cannot. Why is that? What is it about the idea of God that means that its objective reality cannot be inside of me and that it must exist outside of me? It is because the very formal idea of God, the definition of God, contains an objective reality that I could not be the cause of because I know that I myself am an imperfect being. We have already agreed that what has less perfection cannot be the cause of something that has more perfection. I could be, Descartes argues, the cause of all my other ideas, since objectively they contain nothing more than I contain formally, but I cannot be the origin of the content of the formal idea of God, the objective reality of God, since this objective reality contains more perfection than I do. That is to say my picture of God is less than the objective reality of the idea, and thus could not be its cause. This idea must be caused by something that existed outside of me, and it must contain formally speaking as much reality as the objective reality of the idea of God. Only God could be the cause of the idea of God.

So the idea of God necessarily proves that God exists and we have a little chink in the armour of the cogito. There is one thing I know that exist outside of my idea of it, and that is God. But why would that solve my problem with the wax. Why would the existence of God demonstrate that my idea of wax must be what the wax is in nature? It is the existence of God that guarantees the existence of external objects, and also that my idea of these objects correspond to the true nature of external objects. What I can clearly and distinctly perceive is true, but without God this truth would not be sufficient, since although I am perceiving this truth in my mind, there might be nothing like it in the outside world. If I can prove that God exists, then it follows that everything depends upon him, since God is the only perfection, and such a God could not deceive me. It follows, therefore, what I clearly and distinctly perceive, and I can remember having done so, must be actually true.

The success of Descartes’ metaphysical project rests on the existence of God. It would not surprise many readers that no many philosophers, even immediately so, were convinced by it. Cartesian science itself was pretty much left behind with the success of Newton (though he was clearly influenced by Descartes). However, I want to refer to one important critique of Descartes, which is Spinoza. He was as rationalist as Descartes (and thus his critique is very different from the empiricists and Kant who come later), but his argument with Descartes is that he did not take his ideas seriously enough. In other words, Spinoza wanted to out Descartes Descartes.

Spinoza issue’s with Descartes is that he smuggles a theological conception of God into his philosophical idea of God, and that is the idea of creation. There are in fact three substances in Descartes: the two finite substances, mind and matter, and the infinite substance God. This mirrors the theological distinction in the idea of creation of the difference between transcendence and immanence. Now the transcendent God is beyond the comprehension of the finite mind (this is the turning point of the ontological proof for Descartes, I know that God exists, but I don’t know what God is, and God in his absolute power could have created a world in which triangles have 4 sides and 2+2=5). For Spinoza this is absurd. If there were a difference between an infinite God and a finite world, then God would not be infinite, since God would lack something; that is the finite world that is different from him. Also God could not be governed by different laws (as though God were a capricious tyrant), because this would mean that laws that came from God could have been different, but this too would mean that God would lack something, which would be the laws that he did not create. If God is infinite, and we start with this infinite, then the idea of transcendent wilful God that is still at the heart of Descartes’ project (which Spinoza will explain is only anthropomorphic idea of God), must be a fiction. ‘God,’ Spinoza writes, is the immanent, not the transitive, cause of all things’ (1P18).

Rather than explaining attributes in relation to infinite substance, Descartes has explained substance in relation to attributes, and this is why he has ended up with three substances, rather than one unique substance, God, whose essence must infinite attributes (not just two) that express themselves through infinitely many things and ideas. We must begin, Spinoza is saying, with the infinite universe and explain are place within it, rather than projecting an image of ourselves onto this infinite universe.


Ariew, R., 1986. Descartes as Critic of Galileo’s Scientific Methodology. Synthese, 67(1), pp.77–90.

Deleuze, G., 1978. Les Cours de Gilles Deleuze. Sur Spinoza. Available at: http://www.webdeleuze.com/php/texte.php?cle=14&groupe=Spinoza&langue=2 [Accessed October 9, 2014].

Hatfield, G.C., 2014. The Routledge guidebook to Descartes’ Meditations,

Williams, B., 2005. Descartes: The Project of Pure Enquiry, Psychology Press.

[1] He believed that although Galileo was to be admired, he tended to rush over the subject matter and not explain sufficiently. The purpose of Descartes’ project was to set philosophy on firm principles and work from these in a systematic way (Ariew 1986).

[2] This shows that Descartes was not as far from the Scholastics as some have presented him, and indeed, how he sometimes presents himself.

Galileo and the Science of Nature – Lecture 1

March 6, 2015

GalileoWe are interested in science as part of intellectual history. We are not, therefore, concerned whether Galileo’s theories are correct or not in terms of the scientific conception of truth, however mistrustful we might be of such a way of thinking about truth. Nor do we need do pay attention to the specifics of Galileo’s theories, as though we were studying physics, though does not mean that details of his interpretations of nature will be of no concern at all. Rather, what matters to us is how, as non-scientists, our conception of the world has completely changed because of Galileo’s achievements. We live in a completely different world view because of the rise of experimental science in the 16th and 17th centuries, and this has profoundly altered the way we view nature. Galileo’s name, therefore, marks an epochal change in our history, and the present cannot be understood without it.

Before, however, we discuss what it is that is so important about Galileo, let us first say a few things about ‘intellectual history’ or the ‘history of ideas’, which we began to talk about last week. First of all, and perhaps most importantly, what do we mean by history? The fundamental basis of history must be time, for if we were not temporal beings; that is, had a sense of our own past, present and future, then our history as such would not have a meaning for us. Thus, we can talk about this history of rocks, but it unclear that rocks have a history for themselves. Likewise, we can talk about the history of lions, but they themselves do not have their own history.

The time of history is not the same as clock time, though it can be measured by clock time (we say that such and such an historical event happened at such a date and such a time), because it is our own experience of time that is the basis of clock time, and not clock time the basis of our experience of time. Human beings were already historical, have a sense of their own lives and death, and their place in the sweep of generations, long before clock time became the representation of lived time. If we first of all did not live in time, then there would be no calendars and clocks to measure it.

What do we mean by the past of history? It cannot mean just what once happened in the present and now has disappeared into past only to be retrieved in the present like a fish pulled out of the river gasping for air on the bank. In some sense, isn’t the past ahead of us rather than in front of us? Heidegger in Being and Time speaks of there being two meanings of history (1962, pp.424–55). One is the positivism of the past, which marches under the banner of the words of the famous German historian Ranke, who raised the study of history to a proper science, wie es eigentlich gewesen (the past as it actually was). The other, far more difficult to understand, and the sense of history that Heidegger will argue for, is the past as the possibility of the future. He asks what makes something preserved in a museum historical. We are not just speaking of statues and artefacts, but all the kinds of things the historian works with: letters, diaries, memoirs, eye witness accounts, government archives, treaties, and so on. For the positivist, these are the facts of history, and what makes history more than fables and myths. Heidegger does not dispute the reality of these documents nor their importance to the scientific study of history, but he asks a more difficult question: what is the ‘pastness’ of the past? Why, when I hold them in my hand, do I say they belong to the past. What is the status of these past artefacts as past, even though they belong to the present, since I holding these documents in my hands now?

What is at stake here is what we mean by truth, for it is the authenticity of these past documents (that they really belong to the past) that legitimate history and make it different from myth or storytelling. The historian isn’t interested merely in the fact that the battle of Waterloo happened on the 18th of June 1818, but that such an event can be verified by real witness accounts that have been written down and stored in archive. Just as clock time is derivate of lived time, since if human beings did not live in time, then we wouldn’t have clocks, so Heidegger thinks there is a fuller experience of history on which this narrower conception, however important and interesting it is, must rest. Why would we be interested in preserving this past, and why are some pasts more significant than others, since there are pasts that are absolutely lost, and some pasts that now that interest us (the pasts or women and the marginal, for example) that did not interest us before?

Heidegger answer is that the past matters to us because of our present. We can only interpret the past from the vantage point of the present, but this means we see the past in terms of our future. The truth of history is not the collection of supposedly true facts about the past, but how life can be breathed into them so that these lost documents might be retrieved and their burning embers illuminate our world in a new light. We study history because it reveals the present, but in so doing it shines a light forward into our future.

When we come to read Galileo, then, we are not interested in it as a dead object that has nothing to say about our present or our future, but precisely the opposite. The world we live in now is the world picture of Galileo, and the dangers of the future precisely spring out of this future. What is at the heart of Galileo’s projection of nature is mathematics. ‘The book of nature,’ he famously said, is written in the language of mathematics’.[1] Nature was not understood, as it was by the Ancient Greeks, and in the Medieval period, inspired as it was by the writings of Aristotle and other Greek philosophers, as made up of qualities, but as a quantity. What we see, colours, shapes, sizes and sounds, is not what is.

The ancient Greek word for nature is φύσις.[2] Rather than suggesting a mathematical homogenous reality, φύσις is related to the verb φύω, which means to ‘grow, produce or engender’. In latter medical texts of that period, φύσις began to mean not just the process of something (growing, producing, engendering, and so on), but the nature of something, what it is be that thing (Hadot 2004, pp.39–52). It is this notion of φύσις that we find in the works of Plato and Aristotle and which are passed down to our European heritage through the Islamic scholars by the 12th century. It is this intellectual world that is being rejected by Galileo’s hypothesis. Here nature becomes something very different, and its transformation is something that we still live with today.

It is in the next lecture that we shall investigate this transformation metaphysically and not just scientifically (for it is really Descartes who systematises Galileo’s approach and he understands more fully that it requires a whole different way of looking at nature). At this point we only want to describe generally how such a conception of nature is very different from before. It is no longer seen as a living being, but as a machine. It is the machine model of nature that opens it up to mathematisation. It is not that Galileo first sees nature mathematically and then subsequently understands it as a physical quantity, it is because he see nature as machine, whose parts can be explained purely physically, that it is open to the descriptive power of mathematics. It is this physical mathematical model that is still the basis of our modern physics, and affects the way that all view nature and ourselves. The aim of the new science of nature is to uncover those hidden mechanisms behind appearances using the new instruments (like Galileo’s telescope) and technologies, and constructing experiments through which they might be described mathematically.

What is at the heart of the new mechanical, physical, and mathematical model of nature is the belief that reality is homogenous. It is homogeneity of physical reality that is the real revolution of Galileo’s world view. For previously to Galileo, both in Ancient Greek thought, and in the monotheistic faiths, nature was heterogeneous and not homogeneous. Thus, the universe was divided into two distinct spheres, the physical and intelligible in Plato, which was then repeated in Aristotle’s double world view in the difference between the sublunary world and the heavenly spheres. The theistic division of the world into the earthly and heavenly was easily overlaid on top of these philosophical distinctions, such that in the long Scholastic period the one reinforced the other.

From the perspective of the Church, then, especially since there was no empirical proof for Galileo’s Copernicanism, since it was only a hypothesis, the judgement against Galileo was clearly justified. For it overthrew an image of nature that had existed for millennia. What this homogeneity of nature implied (as Spinoza knew only too well), was not that God did not exist, but that there was no unique place for man in the universe. As Freud remarked, the Copernican hypothesis was a blow to man’s pride, not God’s, since God was required to set such a nature in motion, but man certainly wasn’t (1973, pp.284–5). The universe is made of an infinite homogeneous matter, in which there are infinite stars and infinite planets, some no doubt inhabited by beings who equally mistakenly thought they were at the centre of the universe, but who quite obviously were not, just as man isn’t. That later on God dropped out of the model (‘we no longer need this hypothesis,’ as Laplace famously remarked), should not obscure the fact that it was the disappearance of man that led to the disappearance of God, and not the other way around.

You have to read The Dialogue of the Two Chief World Systems with a healthy scepticism (which of course is always the way you should read) (Galilei & Finocchiaro 2008, pp.190–271). Galileo presents the Copernican system as though it were merely an mathematical hypothesis (which is how Copernicus himself understood it), whereas he believed he already had empirical proof that such a motion was real (he even argued erroneously that it was an explanation of the tides on the earth). What you have to understand is what the motion of the earth implied, however much it went against common sense, and why his opponents, who he represents as slaves to their learning and their books, rather than earnest observational study of nature (though it was his theories rather than his observations that were the source for his own hypothesis), were so adamantly against his views. Because to see the earth as in motion meant that there no difference between the earth and the other planets, and thus there was nothing at all distinctive about it.

As he writes at the very beginning of the second day, ‘Independent Mindedness and Aristotle’s Authority’, the traditional view was that the heavenly spheres were ‘ingenerable, indestructible, unchangeable and inert’, whereas the earth was the opposite of this, ‘elemental, generable, degradable, and changeable (Galilei & Finocchiaro 2008, p.193). Galileo’s argument was that there was no difference between the earth and rest of the universe because they were made of one and the same substance, and that the earth is the same as the planet Jupiter, which is clearly moving. It is important to note that Galileo does not get Simplicus (who represents all those who reject the heliocentric view) as not disagreeing with this hypothesis by putting forward a different one, but saying that it disagrees with the authority of Aristotle. Galileo is thereby opposing two different practices of science. One in which observation and theory is fundamental (though he probably overplays the observation, since he already entertained the hypothesis and constructed the experiments to prove them), and the other, traditional and hidebound by the interpretation of texts. The former, Galileo asserts, would have been more attractive to Aristotle than the latter, even though they claim to speak in his name, since he too was a scientist, and if he had looked through Galileo’s telescope would have agreed with him and not his opponents.

If we are going to reject Aristotle, he continues, we do not need another author. The only authority we need is our own senses. Our discussion as proper philosophers should be about the ‘sensible world and not a world on paper’ (Galilei & Finocchiaro 2008, p.201). As we shall see next week, however, it is precisely this world that we cannot see.

[1] He did not actually say this. The quotation is a gloss of a passage in The Assayer. ‘Philosophy is written in this all-encompassing book that is constantly open before our eyes, that is the universe; but it cannot be understood unless one first learns to understand the language and knows the characters in which it is written. It is written in mathematical language, and its characters are triangles, circles, and other geometrical figures; without these it is humanly impossible to understand a word of it, and one wanders around pointlessly in a dark labyrinth’ (Galilei & Finocchiaro 2008, p.183).

[2] For the Liddell and Scott entry for φύσις, see http://tinyurl.com/3a4fsaf. And for φύω, see http://goo.gl/oeZ43f.