As its title suggests, Lu-Adler’s book is both a historical and a philosophical reconstruction of Kant’s theory of logic. Her historical reconstruction, which encompasses chapters 1 to 3 and parts of chapter 4, is meticulous. She draws on a rich array of supporting characters, from Aristotle, to Christian Thomasius’ ‘methodological eclectism’ (p. 18), to John of Salisbury’s ‘humanist’ conception of logic (p. 61) as well as Baconian, Lockean and Wolffian approaches to logic, all in her efforts to trace the rich intellectual history of various theories of logic to contextualize Kant’s logical concerns. Her historical work enables us to hear some of Kant’s oft-cited passages concerning pure general logic in a new register, for example, when Kant claims that pure general logic is a formal science that must be grounded in a priori principles and not psychological ones, not only is he claiming that logic is a normative science (which is often how those passages are read and cited), but he is also taking a definitive stand with respect to an ongoing debate concerning the relation between logic and psychology.
Lu-Adler’s philosophical reconstruction is distinctive because she shifts the centre of gravity away from what one might identify as the ‘general-logic-centric’ nature of the recent literature, and reminds us that his theory of logic encompassed much more. For instance, it included: an account of its possible relation to metaphysics or ontology; a conception of logic as a formal science of the ‘learned’ understanding as opposed to logic considered as a ‘cathartic’ that is proper to a ‘common’ understanding (where this relates to his as yet underappreciated and underexplored distinction between pure and applied logic, the latter which we might now call normative epistemology or a theory of reasoning); an account of what could ground the validity of the norms of logic, insofar as psychology were to be excluded from playing that role; a conception of the role of logic with respect to knowledge acquisition, as an organon of the formal but not material use of our thinking; and an account of how pure general logic is to be possible (which question Kant did not seemingly think to ask explicitly until much later in his career, following a suggestion by Salomon Maimon, cf. 20: 339). This last circumstance is tied to Lu-Adler’s recognition that it is the notion of a transcendental logic that clearly constitutes Kant’s most central contribution to a theory of logic.
Turning now to the book’s contents, in chapter 1, ‘Kant and a Philosophical History of Logic: Methodological Reflections’, Lu-Adler outlines the methodology that guides her historical reconstruction. She begins with an assessment of Kant’s logical corpus, which comprises four sets of materials: the Jäsche Logic, his handwritten notes on logic (the so-called Reflexionen), transcripts of his logical lectures and his remarks concerning logic that are scattered throughout his published works, most notably the Critique of Pure Reason, though none of these alone give us a definitive picture of the Kantian theory of logic. Complicating matters is the question of textual authenticity surrounding the Jäsche Logic and the extent of Kant’s involvement in its publication. But this question of authenticity is the occasion for Lu-Adler’s first distinctive methodological strategy. Rather than treating the Jäsche Logic as a definitive statement of Kant’s received positions in his logical theory as some have done, Lu-Adler treats the Jäsche Logic as itself a historical text and but one source among many. These sources provide Lu-Adler with the raw materials with reference to which she is able to map out Kant’s intellectual milieu, since the philosophers mentioned in the Jäsche Logic include Aristotle, Lambert, Leibniz, Wolff, Locke and Baumgarten (9: 21), who all, in turn, take some kind of stand with respect to contemporary controversy concerning logic.
The theme of chapter 2, ‘The Nature and Place of Logic: A History of Controversies’, is that scholars have disagreed as to the value and nature of logic. Kant’s views on logic, then, must be seen as similarly evolved and responding to the history of such disagreement. Lu-Adler organizes the set of concerns that philosophers had concerning logic prior to Kant’s time with the following four questions (p. 65):
(1) Is logic a science (scientia), instrument (organon), standard of assessment (canon), or mixture of these?
(2) If logic is a (theoretical) science, what is the subject matter that separates it from other sciences, particularly metaphysics?
(3) If logic is a necessary instrument for all philosophical inquiries, how is it entitled to this position? What is the end (finis) of logic?
(4) If logic is both a science and an instrument, how are these two roles related?
In this chapter, Lu-Adler begins with Aristotle, the Stoics and Epicurus. Kant famously begins the Groundwork with an endorsement of the Stoic division of philosophy into logic, physics and ethics (cf. 4: 487). And given that much of Kant’s conception of Aristotelian logic is itself shaped by Aristotle’s medieval commentators, Lu-Adler examines the views of Boethius, Avicenna, Averroës and Aquinas, who all have nuanced discussions of logic (p. 2). Lu-Adler’s treatment in this chapter of Aquinas’ views and their possible indirect influence on Kant is particularly informative, as Aquinas’ distinction of theoretical science in terms of a special science that is about a determinate set of objects and a general or universal science (metaphysics) clearly foreshadows a distinction that Kant will later make in the first Critique, albeit in terms of a particular and general use of the faculty of the understanding (A52/B76). Further supporting characters include Walter Burley, William of Ockham and Jacopo Zabarella, the latter of whom merits special attention as an esteemed Aristotelian who was taken seriously by Kant’s immediate German predecessors such as Baumgarten.
In chapter 3, ‘The Making of a Scientific Logic from Bacon to Wolff’, Lu-Adler turns her attention to four individuals, Bacon, Locke, Leibniz and Wolff, and considers their positions on the following three questions (p. 97):
(a) If logic is to be a science, what are its grounding principles, and whence does it draw such principles?
(b) Assuming logic is not engaged in direct, domain-specific inquiries of the world, is it nevertheless uniquely positioned to provide tools and guidance for such inquiries?
(c) How is logic related to the overall project or aim of philosophy, namely the perfection to which human reason is supposedly destined (in both the theoretical and practical realms)?
According to Lu-Adler, Bacon believes that one of the roles of logic is to free us from external and internal sources of prejudice (p. 76), with which Kant signals his agreement in his notion of an ‘applied logic’. Kant believes Locke was right to identify the ground of logic as an analysis of the capacity for thought or the human intellect, but was mistaken to think that such an analysis could be done on empirical or physiological grounds. Kant will agree with Leibniz that logic can become a formal and general science like geometry (p. 88), but will argue that the method of mathematicians differs fundamentally from that of the philosophers. And finally, Wolff believes that our fundamental logical principles (such as the law of non-contradiction) are ultimately grounded in terms of fundamental ontological and psychological truths, a belief that Kant will explicate in his own way with his notion of a formal idealism: that the laws of logic or of our pure thinking determine the form of our possible experience.
In chapter 4, ‘Kant on the Way to his own Philosophy of Logic’, Lu-Adler considers how the above sheds light on the development of the pre-Critical Kant’s theory of logic. Here, the two transcripts of his early logic lectures, namely the Logik Blomberg and the Logik Philippi, are particularly salient, as well as the philosophical views of three of Kant’s immediate predecessors, namely Knutzen, Baumgarten and Meier (the author of the logic textbook used by Kant). Two questions drive the dialectic in this chapter: the relations between logic, ordinary reasoning and psychology; and the relation between logic and metaphysics. One of Lu-Adler’s main claims in this chapter is that Kant’s notion of a transcendental logic does not emerge from any philosophical concerns about logic, but in fact from questions concerning metaphysics and ontology (p.139).
In chapter 5, ‘Logic and the Demands of Kantian “Science”’, all of Lu-Adler’s historical and philosophical reconstructions culminate in explaining Kant’s mature positions, especially those found in the Critique of Pure Reason. There is much material covered here, with consequences for issues in Kant’s philosophy, including: how to understand the formality and generality of Kantian logical laws; whether to understand Kantian logical laws as constitutive or normative for thinking (or possibly both); as well as Kant’s distinction between general and transcendental logic.
Let me end this review by turning to Lu-Adler’s treatment of Kant’s infamous ‘completeness’ claim concerning Aristotelian logic. Rather than a claim concerning the completeness of Aristotelian logic, Lu-Adler suggests that, in light of the different controversies surrounding the nature and value of logic that she has canvassed throughout her book, Kant’s claim is in fact a claim concerning the ‘nature of logic’, amounting to ‘a philosophical stand on the nature of logic as such and affirming its status as a science of the formal rules of all thinking’ (p. 178).
Lu-Adler’s book demonstrates that not only did Kant take some time to come to and fully develop this conception of logic, but that it is one that was in part enabled by the philosophical efforts of the supporting cast of characters before him. Central to this process was Kant’s realization that a critique of the boundaries and limits of our faculty of the understanding is required if we are to place metaphysics on the secure path of a science. Logic is thus for Kant a form of ‘self-cognition’: the use of the understanding with respect to its own activities and determining the possible boundaries of their use. Kant invents the notion of a transcendental logic as an account of how such a critique must be done. And insofar as transcendental logic is to be possible as a science at all, it must first identify with absolute certainty a set of concepts and only those concepts that exhaust and otherwise completely determine the capacity of the understanding. Now, geometry and natural science (physics) ground the Transcendental Aesthetic; they validate space and time as pure forms of our sensibility. By contrast, during the period in which Kant is writing the first Critique, he does not believe there is a comparable complete science that he could rely on to identify and justify the use of pure concepts. The very need for a logic or science that is demarcated in terms of its generality (abstracting from differences between objects) and its purity (being completely a priori) – namely, pure general logic – is Kant’s solution to that problem. In other words, it is the need for transcendental logic that otherwise grounds the possibility of pure general logic as a science; and the need for a complete set of pure concepts for the former guides the possible search for a complete table of judgements in the latter.
According to Lu-Adler, the completeness claim is not a claim that amounts to a discovery or a formal derivation through which Kant took himself to ‘prove’ the completeness of general logic. Rather, it amounts to the claim that completeness is a demand that is borne out by the very project of a transcendental logic which he then brings to bear upon the notion of a pure general logic. With this insight, Kant needs only to survey the ‘customary techniques’ of his contemporary logicians (A70–1/B96) and, in terms of his critical eclecticism, finally give a transcendental account or explication of logical form (cf. B139–42). By Kant’s lights, the Aristotelian logicians, through their technical and formal treatments of syllogistic inferences and formation rules for judgements, are in fact studying forms of synthesis, or the ‘way to bring given cognitions to the objective unity of apperception’ (B140). This gives us Kant’s Metaphysical Deduction. And insofar as we can show, as Lu-Adler does, on Kant’s behalf, a reasonable method for organizing the four groups of three forms of judgement in his table of judgements (pp. 185–6), this would be enough to give us a plausible rendering of the completeness claim, or what Lu-Adler presents as a ‘kind of proof he may give’ for the completeness claim, ‘without dwelling on how each one of those rules is supposed to be derived exactly’ (p. 187).
I have, in any case, only scratched the surface of the many insights concerning Kant’s theory of logic and its historical context in Lu-Adler’s book. I highly recommend it, and I know I will find myself returning to it again.
