The Dialectic is frequently represented in a wholly negative way: as Kant’s criticism of the use of theoretical reason outside the spheres of mathematics and natural science (as well as everyday sense experience). Certainly, the Dialectic does have this important negative side. But if we are to understand the place of the First Critique in Kant’s overall critical system, it is imperative also to grasp a more positive side to his attack on metaphysics, as traditionally conceived.
We saw that, in the course of this attack, he maintains that it must be impossible theoretically to prove or disprove freedom of the will, the immortality of the soul, or the existence of God. But this impossibility, it transpires, is fortunate: fortunate for morality quite as much as for our positive beliefs in freedom, immortality and God. Since, as he points out in the Preface to the second edition of the First Critique, if we do not embrace his Copernican revolution, we shall have to renounce these metaphysical beliefs; and this, in turn, will mean our acknowledging that the demands of morality are delusory (B xxvii–xxx).
But why does Kant suppose that his Copernican revolution is necessary for holding on to our central metaphysical beliefs? The answer is that he thinks that if we do not distinguish the world of our senses (the spatio-temporal world) from the world as it is in itself (the world that exists independently of our possible sense experience), then the deterministic laws that provably obtain in the sensible world must apply to us as moral agents. It would, in short, be impossible for us even to assume freedom of the will (see the Antithesis and Observation of the Third Antinomy). Equally, we should have to renounce our belief in a necessary Being who has created and sustains the universe; since, without the distinction, it is provably impossible that such a Being could exist (see the Antithesis and Observation of the Fourth Antinomy). Lastly, the belief that the soul is simple – and, therewith, the possibility of believing in the continuation of the soul after the death of the body – must be rejected, unless the world of the senses is distinguished from the world as it is in itself (see the Antithesis and Observation of the Second Antinomy).
Moreover, if it is impossible even to assume the existence of free will, God and the immortality of the soul, without embracing Kant’s Copernican revolution, then since – as he himself argues – these are necessary presuppositions of morality, it follows that the demands of morality must themselves be delusory.That is why Kant asserts:‘I have therefore found it necessary to deny knowledge in order to make room for faith’ (CPR,B xxx; italics original).
This famous assertion should not be taken merely as showing that, in order to save scientific knowledge, Kant accepted that we would have to deny ourselves any knowledge of the central claims of metaphysics (while leaving open the possibility of our believing in them). It implies something far stronger. It implies that if the traditional picture of our relationship with the world of the senses is correct, then we should actually be precluded from even believing in the existence of free will, God and immortality – since we would then be in possession of proofs of the impossibility of each of these beliefs. Only if we embrace Kant’s Copernican picture can we deny the force of the proofs, and thereby make room for the beliefs that are necessary for morality. So the metaphysical discussions in the Dialectic secure our belief in God, freedom and immortality – and thereby in morality also – against inevitable scepticism.
The First Critique, then, not only seeks to explain how there can be universal and necessary knowledge of objects in mathematics and in natural science, it also seeks to leave a space open for morality.As Kant sees it, neither the theoretical nor the practical side to our lives can be sustained on the traditional picture. On his Copernican picture, on the other hand, we can – in fact do – have both. The positive contribution of the Dialectic is to show how it is possible for the moral life to exist – and therewith to lay the ground for the practical proofs of just those central metaphysical claims (concerning freedom of the will, the immortality of the soul, and the existence of God) that, as he had argued earlier, our theoretical reason is, in reality, powerless to prove or disprove.
2 The Division of Judgments, and the Status of Mathematics and Natural Science
Before embarking on a more detailed look at Kant’s system, we need to do two things. First, we need to understand some of his terminology, especially with regard to his division of judgments into three types. Second, we need to understand more fully the status that he accords to judgments in mathematics and natural science.
The division of judgments
Kant identifies three possible types of judgment:
1 Analytic a priori judgments;
2 Synthetic a posteriori judgments;
3 Synthetic a priori judgments.
In order to explain this threefold division, he further distinguishes between analytic and synthetic judgments, on the one hand, and a priori and a posteriori judgments, on the other. These further distinctions can be explained as follows.
An analytic judgment is one in which the meaning of the predicate term is included in the meaning of the subject term. Example: ‘All bachelors are unmarried (men).’ Kant notes that the denial of an analytic judgment is self-contradictory (as in ‘It is not the case that all bachelors are unmarried’).
A synthetic judgment is one in which the meaning of the predicate term is not contained in the meaning of the subject term. Example: ‘All men are mortal.’ Accordingly, the denial of a synthetic judgment is not self-contradictory. (The judgment ‘It is not the case that all men are mortal’ is doubtless false; but it is not self-contradictory, given the meaning of ‘men’ and ‘mortal’, etc.)
An a priori judgment is a judgment that is thought of as holding independently of experience. Kant says that there are two ‘sure criteria’ of, two infallible ways of identifying, an a priori judgment. If a judgment claims to hold either with necessity or strict universality, then it must be an a priori judgment. For no judgment that depends on experience can be thought of as holding either necessarily or with strict universality. Experience can show that some judgment is or is not the case, but not that it necessarily is or is not the case (or must or must not be the case). Similarly, while experience can show that all instances so far examined of a particular unrestricted class are such-and-such, it cannot show that all past, present and future instances of that class are such-and-such. The most that our evidence to date can entitle us to claim, assuming it is wide-ranging and that no counter-examples have been encountered, is what Kant calls ‘comparative universality’. That is, we may employ an inductive argument on the basis of our experiential evidence to date, and claim that all instances are probably such-and-such. But cases of comparative universality are not cases of strict universality (where ‘no exception is allowed as possible’ (B 4)). Throughout his critical works, whenever Kant discusses universality, he means strict, not comparative, universality unless he says otherwise.
It is worth noting that Kant does not define an a priori judgment as one that claims to hold with necessity and/or universality. For him, an a priori judgment is defined as one that is thought of as holding independently of experience. But if we can discover a judgment that does claim to hold with necessity and/or universality, then we can be sure that it is a priori. Necessity and universality are infallible means of recognizing an a priori judgment.
Given his definition of an a priori judgment, we can understand Kant’s claim that besides a priori judgments (or principles) there may also be – indeed, are – a priori concepts. For example, he holds that the concept of cause is an a priori