Kant’s transcendental logic is novel, and should be considered as significant for the history of logic as Gottfried Wilhelm Leibniz’s mathesis universalis. The transcendental logic as represented in the first Critique is composed of two parts: analytic and dialectic. The analytic concerns the cognitions of the understanding, and the dialectic the cognitions of reason. Kant calls the analytic part of the transcendental logic an analytic of truth, because only the cognition of the understanding can be said to be objectively true or false. The ideas of reason, because they pass beyond the bounds of experience, are undecidable and thus do not directly add anything to our picture of the world. Thought at the level of the understanding does have a decidable, objectively true or false content, since in all of its functions it is intrinsically oriented to the givenness of an object of pure or empirical intuition. It is thus through the understanding that human thought can claim to know the world it experiences and perceives.

Kant’s purpose in the introduction to the transcendental logic is not to introduce us to logic. He takes it to be something with which he can presume his reading public to be acquainted. Kant’s presentation of logic in this context is very concise, even compared to his published Jäsche logic. It is strategic – it leaves out what elsewhere he goes into in great detail. Kant tells us as much as we need to know about logic in order for him to introduce us to the possibility and nature of an ‘other’ logic. This other logic concerns the form of thought in relation to any possible experience. After showing in the transcendental aesthetic that the a priori forms of intuition, our capacity for receptivity, are time and space, Kant in the transcendental logic begins to lay out the a priori forms of thought, or spontaneity. He ‘uses’ the tradition of logic to introduce us to something, he claims, we have never thought of before.

The introduction is titled ‘Introduction to the Idea of a Transcendental Logic.’ Ostensibly this introduction is to introduce us to the idea of a transcendental logic and to prepare us for both of its specific divisions. As such, it is an introduction to the analytic as much as it is of the dialectic. This new logic to which Kant is introducing us catalogues the conditions that make cognition and experience possible (analytic of the concepts of understanding), as well as points out the limits beyond which human knowing cannot go (dialectic of the ideas of reason). This obvious interpretation of the introduction is reasonable and questionable. It can be challenged by considering what immediately follows the introduction – the first book of the Analytic of Concepts, and specifically the metaphysical deduction. The importance of the introduction is not just structural or general in laying out the disciplinary difference between the two logics, but chronological – it has a specific import for what follows linearly immediately after it. His introduction not only uses logic to introduce us to transcendental logic but more importantly to set the stage for the use of logic as a clue for the contents of the transcendental logic. Thus not only the possibility but also the actual content of transcendental logic takes its cue from logic.

The first chapter of the transcendental analytic’s first book contains what in the B edition Kant calls the metaphysical deduction of the categories. The metaphysical deduction is one that moves from the traditional doctrines of logic to the necessary and universal structures of the mind. Kant titles the section in which the metaphysical deduction is found ‘The Clue to the Discovery of all Pure Concepts of the Understanding.’ Scholars place different emphasis on the connotation of the word ‘clue,’ and a good number question Kant’s assessment of these passages as in any way containing a deduction. As a clue, logic provides a guidepost for discerning the more basic principles involved in experience and cognition; it suggests something to us about the nature of the mind. While the knowledge of the world is always growing and expanding, the framework or structure of the one who does the knowing is constant and unchanging.

From the section on the clue, Kant moves into the more complex and difficult arguments of the transcendental deduction, with its historically significant reference to the transcendental unity of apperception. What tends to be interpreted as the decisive moment of Kant’s critical philosophy is structurally dependent upon a view of logic that is disclosed in the introduction, and made use of in the ‘clue’ section. Because of the leverage that logic provides for the real work of the Analytic of Concepts (and its first section particularly), we would be wise, perhaps, not to interpret the purpose of the introduction in accordance with what its title suggests. It is as if for the sake of its function as clue the introduction provides us a reminder, a quick refresher course on the idea of logic.

Kant’s first step in characterizing the nature of ‘logic in general’ does not happen until the end of the second paragraph. This characterization serves largely a context-dependent function. Logic is introduced into the discussion to make the distinction between an analysis of the understanding and an analysis of sensibility. The distinction between logic and the aesthetic is presented consistently throughout Kant’s lectures on logic primarily in the context of the ‘perfections of cognition,’ and is also found in G. F. Meier’s Vernunftlehre. I take Kant’s point in this context to be that logic and the aesthetic are both general – they pertain to a whole set of objects without exception. The aesthetic as ‘the science of the rules of sensibility in general,’ and logic as ‘the science of the rules of understanding in general’ (CPR, A52/B76) explicate norms or functions that make any of the particular sciences possible, and whose consistency is guaranteed, as we will see, by the same source of the consistency of experience.

Thus, Kant starts talking about logic at the brink of an analogy: just as a transcendental aesthetic deduces the conditions of possibility for the objects of sensibility/receptivity, a transcendental logic deduces the conditions of possibility for the objects of thought/spontaneity. This distinction between aesthetic and logic is not found in comparable discussions of logic elsewhere in the Critique, neither in the Analytic of Principles nor in the Transcendental Dialectic. This serves to emphasize the singular importance of logic at this particular juncture in Kant’s overall argument. On the one hand it is introduced immediately after the conclusion of the transcendental aesthetic, that is, analysis of the a priori forms of intuition, and on the other it serves to introduce the necessity and nature of a transcendental logic, that is, analysis of the a priori forms of thought. In other words it is doubly a function of transition – it transitions us from the transcendental aesthetic to the transcendental logic as a whole, and it provides us a clue into the most primordial structures of mind.

The second definitive step Kant takes is to divide logic into general (allgemeinen) and particular (Verstandesgebrauchs). This division of logic is first in the order of exposition in the Jäsche logic as well as in Meier’s Vernunftlehre. It serves to restrict the nature of logic by distinguishing it from the logics of particular disciplines. It is thus a formal canon of thought as such and not an organon of a particular science:

In contrast to general logic is a logic conditioned by a particular kind of object or domain of inquiry a logic that has ‘regard to the difference of the objects to which it may be directed.’ ‘The logic of the particular use of the understanding contains the rules for correctly thinking about a certain kinds of object.’ Such a logic would function as the organon for a particular science. Still formal in the sense of not having a material content of its own, a particular logic is differentiated from others by the set of objects investigated by the particular science of which it is the organon. It provides the parameters within which a determinate set of objects external to thought can be cognized. The organon of biology would be distinct from the organon of architecture, while the canon of thought, general logic, would apply to them both and function as a common assumption. An organon and the science it frames would both necessarily agree with the rules set out by general logic, but would also involve a determination that goes beyond the operations of the understanding in abstraction from sensibility, or perhaps more saliently, objects in general. Particular logic, as ‘the rules for correctly thinking about a certain kind of object,’ is one step removed from the universality characteristic of elementary logic. Particular logic has a conditioned generality, one that is circumscribed by the limits of its discipline. ‘In the schools the latter (the organon) is often stuck before the sciences as their propaedeutic, though in the course of human reason they are the latest to be reached, once the science is long complete…. For one must already know the objects rather well if one will offer the rules for how a science of them is to be brought about.’ The parameters formulated by a particular logic are at once the basic operating principles of a particular science and the ‘latest to be reached.’ An organon presumes an entire field of investigation that it then formalizes.

This division between general and particular logic is also found in the Jäsche logic, although the terminology is slightly altered. However, Kant is consistent in the characteristics or marks by which he defines and differentiates general logic. He characterizes the rules of logic as necessary, while those of determinate sciences or mathematics are contingent (JL, 13/528). This division rests on the fact that in general logic the rules are grounded in the operations of the understanding taken by itself and thus are necessary for all thought, while in the contingent logic the rules are determined in accordance with the presence of an object to the understanding. The rules for the very operation or activity of thought taken independently of an object are necessary and the specific subject matter of general logic. ‘We cannot think, we cannot use our understanding, except in according to certain rules.’ The organon of a branch of math or physics is contingent because it concerns the relation of the understanding to the type of object given to thought by an empirical or pure intuition. This determinate relation of thought to a particular kind of intuitive object/appearance implies the contingency of the logic of that science, and is why these sciences involve synthetic cognition and are not merely analytic.

In the Dohna-Wundlacken logic we read the following: ‘Logic abstracts from all content, hence also from all cognition and it is not an organon. But mathematics is not only a canon but also an excellent organon…’ (DW, 696/434). Mathematics, in contrast to general logic, has a relation to the possibility of objects of experience – it has a particular relation to intuition which differentiates it from other forms of cognition. Mathematics based on pure intuition has the universality requisite for being an organon for any science of objects in space and time, but not the universality requisite for being the form of thought itself. The presence of the element of particularity, exteriority, or contingency in thought explains why these sciences involve synthetic cognition and are not merely analytic. The specificity of the logic Kant is laying out involves a necessity that applies to all acts of thought: