Although in this course we are focusing on the first part of the Transcendental Doctrine of Elements, it is worth our while, especially when it comes to Kant’s critique of Descartes, to set this argument within the broader aim of the Critique of Pure Reason. One way of thinking about Kant’s work is as a critique of philosophical theology (as we can see for this reason why he rejects Descartes) We might see the aim of Kant’s critique of philosophical theology as follows: he aims to deflate the pretensions of a rational theology in order to make room for a theology that is based up morality. The first is a negative critique of religion, the second a positive one. Let us first investigate the negative critique of philosophical theology.
Like with all the other topics of the Dialectic, the source of the theological error is to treat ideas of reason as though they were objects of human intuition. Or to put it another way, the error of dialectical reasoning for Kant, is to treat a condition of human knowledge as though it were actually an object of human knowledge. The idea that is falsely transformed into an object in speculative theology for Kant is the idea of a necessary being, and it has it most classical form in the ontological argument. Kant’s critique of the ontological argument is justifiably famous, and in fact even those who disagree with the overall aim of transcendental idealism, will support Kant’s devastating demolition of perhaps the cornerstone of 18th century metaphysics (we only have to remind ourselves of the importance of this argument for Descartes’s metaphysical solution of the agreement between the subjective and objective realms of human knowledge).
Before, however, we get to Kant’s critique of the ontological argument and therefore rational theology’s pretensions to absolute knowledge, we need to inquire about the limitations of human knowledge for Kant.
For Kant, there are two sources of human knowledge, concepts and intuitions. This means that for Kant our understanding of the world cannot be limited wholly to our experience of it. This is the paradox of philosophy’s explanation of experience (this is true from Plato onwards and not just Kant): we can only explain experience by going beyond experience. Why is this so? It is because the human understanding of the world is conceptual. I do not just immediately grasp objects outside of me; rather my knowledge of them is mediated by my cognitive faculties. These Kant describes as the ‘pure categories of the understanding.’ Also for Kant, no matter what object I am experiencing, whether it is inner or outer, this object has a temporal and spatial form, which is not given by the object itself, but through my perception of it that, so to speak, clothes it in this spatial and temporal form. Space and time, for Kant belong to consciousness and not to objects themselves.
There are, however, important consequences that follow from this hypothesis that my knowledge of objects is shaped, formed and conditioned by the very mode in which I know them. It would mean that I could never know objects as they are in themselves outside of the form of human cognition. Thus Kant makes a distinction between the thing in itself and appearance, or the noumenon and the phenomenon. The philosophical problem is what is the status of this mysterious thing in itself or Noumenon?
Our error might be to think of it as a mysterious object that lies behind the appearance, in the way for example that classical metaphysics thinks of the difference between essence and appearance. As we might see, for example, in Plato’s example of the perfect from of the bed of which the bed on which you lie down on at night is merely an imperfect copy. None the less, it is clear for Kant that the thing in itself or the noumenon cannot be such a mysterious object. For an object for Kant is not something that lies outside of human knowledge, and which thereby can be contrasted to appearances; rather the object is the result of appearance being schematised by the categories of the pure understanding.
The only meaning of the thing in itself or the noumenon for Kant must be methodological; that is to say that it follows from the meaning of appearance that we posit the notion of the thing in itself and regulative, that It does not follow, however, that we can assert any knowledge of the thing in itself, except negatively; for example, the thing in itself would be outside of space and time, since the latter are forms of human intuition. In other words, the function of the idea of the thing in itself is merely to tell us what the idea of appearance must contain, but it does not inform us about the objective reality of the thing outside of human cognition.
This brings us back to philosophical or rational theology. For it is the mistake of such a rational theology to make an assertion about the existence of such things that by definition lie outside human sensible intuition. Its error, as we have already described it, is to confuse an idea, for we can all think of the formal definition of God, with an object. This error is possible, because our conceptual ordering of our intuitions certainly extends beyond them (if they did not then all we would have would be intuitions and there would be no a priori component of human knowledge), but the illusion is brought about by asserting that what extends beyond can also extend the limits of the possible objects of human knowledge. Knowledge is the unity of concepts and intuitions, and concepts by themselves only produce fictitious objects.
Kant uses the example of the sea to vividly capture the limits of human knowledge:
This domain is an island, enclosed by nature itself within unalterable limits. It is the land of truth – enchanting name – surrounded by a wide and stormy ocean, the native home of illusion, where many a fog bank and many a swiftly melting iceberg give the deceptive appearance of father shores, deluding the adventurous seafarer ever anew with empty hopes, and engaging him in enterprises which he can never abandon and yet is unable to carry to completion. [A235-6/B294-5]
We might argue, therefore, that the rational theologist has not only sailed away from the coastline, but she is unfurling her conceptual sails to head out into the open sea to be lost forever.
Rational theology hopes to prove the existence of God. It does by arguing from an idea to an object. There are three possible arguments for the existence God, Kant argues, in Western philosophy: the ontological, the cosmological and the teleological. In each case the error is to jump from mere the mere idea of necessary being to the existence of a necessary being. One cannot, however, jump from an idea to an object. On the contrary an object must be given via intuitions, which are never simply logically produced but are given through experience.
Let us take the ontological argument as our example, because Kant believes that all the arguments for the existence end with some form of the ontological argument. Also it is here that we find Kant most sustained critique of Descartes’s argument for the existence of God that is at the heart of his metaphysics. The mistake the ontological argument makes is to confuse logical possibility with real possibility. Kant writes at the end of his critique the following:
The attempt to establish the existence of a supreme being by means of the famous ontological argument of Descartes is therefore merely so much labour and effort lost; we can no more extend our stock of theoretical insight by mere ideas, than a merchant can better his position by adding a few noughts to his cash account. A602/B630.
None the less, this argument is more than merely a logical one. It marks the end of certain conception of God as a possible theoretical object. And this is because beneath Kant’s argument is a completely different metaphysics of objects. A possible object must be a given object, and not merely a logical one. Thus all philosophical discussion of God as object must be rejected. God becomes an idea. But the validity of all classical arguments of God rest on treating the concept as a concept of a possible object. To show that God cannot be object is to demonstrate that all metaphysical discussion about God’s nature is useless.
This destruction of the God of rational theology, however, makes room for the God of faith. This God is not an object, but a moral idea, whose proof is its necessity for human morality, and not for the explanation of reality (an explanation that human reason does not require). Transcendental theology only goes halfway. It purifies the concept of God of any empirical content. It is only with moral theology, where the necessity of religion, to moral life is postulated, that this absence is made good. Of course, if one does not think that the idea of God is necessary to morality, then no pseudo-rationality will make this absence good either. This is the source of Nietzsche’s critique and the idea of the ‘death of God’.
Kant, however, certainly does think that the idea of God is necessary to morality, and he argues this in the postulates of pure practical reason:
By a postulate of pure practical reason, I understand a theoretical proposition which is not as such demonstrable, but which is inseparable corollary of an a priori unconditionally valid practical law (Kant 1956, p.127).
Kant means by saying that it is indemonstrable is that we should not confuse this moral necessity with any kind of theoretical necessity. The moral certainty of the idea of God is not a substitute for the theological arguments that have been eliminated in the Critique of Pure Reason, but only expresses a subjective necessity in terms of the moral order of reason. In theoretical reason, the dialectic emerges when reason demands a totality of conditions, but this would require that reason could exceed the limits of experience, which it manifestly cannot do. Moral reason, however, also seeks its own totality, but in this case it is not a totality of things, but the ‘highest good’. This is defined by Kant as the conjunction of happiness and virtue in proportion to the moral law. The question is not whether we can achieve this, but whether this idea is necessary to our own conception of ourselves as moral beings.
It is manifestly the case that in reality there is no conjunction between virtue and happiness; the rich are happy and the poor suffer. This conjunction can only be an ideal, and this is the function of religion. There is no common ground between my moral intentions and the world. I must therefore postulate an ‘author of nature’ who ensures an identity between the moral world and this world, such that the rich shall suffer and the poor will be happy. It is, to use Kant’s expression, ‘morally necessary to assume the existence of God’ (Kant 1956, p.131).
Freedom, immortality and God are the postulates of practical reason, without them Kant argues the notion of the highest good would be impossible. We should not think, however, that the postulates prove the actual existence of God. They are only immanent to morality and have no proper meaning outside of it. There is, therefore for Kant, no corresponding object or intuition to the idea of God. It is produced only from out of the moral law that resides within us.
Kant, I., 1956. Critique of Practical Reason, New York: Liberal Arts Press.
Kant, I., 1998. Critique of Pure Reason P. Guyer & A. W. Wood, eds., Cambridge; New York: Cambridge University Press.