James O’Shea has written a concise and comprehensive introduction to the main themes of Kant’s first Critique. Following a suggestion Kant made in letters written to Markus Herz in 1781 and Christian Garve in 1798, O’Shea uses the Antinomy of Pure Reason as a guide for his exposition. In the antinomies and their resolution, Kant gives a condensed treatment of his general claim that we are capable of asking certain questions for which, while we cannot know the answers to them, we can know that we cannot know the answers. By taking the antinomies as a point of orientation, this approach has the advantage that the baroque character of Kant’s system is made sense of in terms of the problems his resources are meant to resolve – in particular, concerning the need to restrict reason’s speculative attempts to apply concepts outside the bounds of their proper application. With many of the most difficult elements of Kant’s theoretical philosophy drawn on in addressing the antinomies, and with copious references to both historical and more recent secondary literature on the issues he discusses, O’Shea has written a book that succeeds at being both a solid introduction to Kant for novices and a text that helps more experienced readers familiarize themselves with a line of thinking that is central to Kant’s theoretical philosophy.

O’Shea’s Introduction offers some bibliographical details on Kant, surveys his institutional setting and some of the intellectual influences on his work, and outlines his views on the metaphysics of nature and of morals. Much of the next two chapters is devoted to introducing crucial Kantian distinctions. Chapter 1 covers Kant’s criticism of traditional metaphysics and provides an overview of Kant’s take on the questions of the existence of God, the immortality of the soul and human freedom. The reader is also familiarized with Kant’s transcendental idealism, the a priori/a posteriori distinction, and the distinction between appearances and things in themselves.

Chapter 2 puts Hume’s sceptical views on causality to good effect in explaining the breakthrough that led to Kant’s own perspective on the status of causality. Here we are introduced to the analytic/synthetic distinction, and the question of how synthetic a priori judgements are possible. Chapter 2 also contains the first detailed discussion of the antinomies, as well as an outline of Kant’s solution. Part of what is so effective about this discussion is that O’Shea manages to pull it off without having to bring in issues regarding the status of intuitions in space and time, the categories and logical functions of judgement, or the joint contribution that intuition and category make to human cognition.

Chapters 3 and 4 draw the resources introduced in the previous chapters together to explain Kant’s theory of human cognition and the possibility of synthetic a priori knowledge. The first half of Chapter 3 focuses on the status of space and time as the pure forms of sensory intuition, and the discussion follows that of the first Critique fairly closely. The second half offers an assessment of Kant’s views on space and time, particularly in light of the subsequent development of non-Euclidean geometries, and of the problem the transcendental idealist faces concerning whether and how things in themselves affect human cognition.

Chapter 4 focuses on the categories as the a priori forms of understanding, their metaphysical deduction from the logical functions of judgement, their transcendental deduction as the basis of any possible cognition of an object, their relation to the apperceptive unity or ‘I think’ that implicitly accompanies any cognition, and an assessment of the transcendental deduction. Once again Hume is used as a foil. This material is some of the most difficult in Kant’s Critique. O’Shea does an admirable job in distinguishing and relating the metaphysical and transcendental deductions, explaining how the categories make objective cognition of the world possible, and relating these results to the illicit attempt to extend the application of the categories beyond the bounds of sense that has been a guiding theme of the book (here with regard to the Paralogisms and the attempt to conclude that the ‘I think’ accompanying all cognition can be known to be the act of a persisting substance). As with Chapter 3, this chapter finishes with an assessment of Kant’s effort, and a discussion concerning whether later logicians made Kant’s deduction of the categories on the basis of the logical function of judgements obsolete.

Chapter 5 concerns the Principles of the Understanding as rules for applying the categories to spatiotemporal content in making a judgement. This chapter covers material from the Analytic of Principles, focusing on the Schematism, the Axioms of Intuition, the Anticipations of Perception, the first two Analogies of Experience (concerning substance and causality), and the Refutation of Idealism. The theme of this discussion is the basis of our knowledge of the world as a unified whole subject to scientific and metaphysical inquiry. It is a testament to O’Shea’s reconstruction, and the discussion of the first four chapters, that the material in Chapter 5 can be dealt with in this detail after only 150 pages of preparation. This chapter and the next are likely to be of most interest to more seasoned readers of Kant. The discussion of the concepts of substance and causality vis-à-vis our a priori and a posteriori knowledge of the world ties together many of Kant’s leading ideas, and the treatment of modality as a rule that governs representations, rather than some additional content represented in a judgement, bears on contemporary research into modality.

Chapter 6 discusses the negative and positive roles of reason in developing a metaphysics of nature, particularly concerning the arguments for the existence of God in ‘The Ideal of Pure Reason’ and the discussion of the maxims of reason as regulative principles in the appendix to the Transcendental Dialectic. I did not find O’Shea’s discussion of Kant’s treatment of the arguments for God’s existence to advance the line of exposition beyond what O’Shea had already covered, but the discussion of the Maxims of Reason further develops Kant’s view on the scope and limitation of our a priori knowledge of the world. If Kant is right, I can know before looking into a room that what I will discover there will be understood in terms of the categories – for judgement itself takes the shape of the categories. On the other hand, whether what I see is some (quantity) actual (modality) red cup on a table (quality and relation) is a matter of a posteriori discovery. Similarly, that there must be laws of nature is, Kant thinks, something we can know a priori. But to determine just what quantitative ratios obtain in a given law of nature requires empirical observation. Here Kant threads the needle between the claim that we can know a priori that nature is governed by some laws (a claim in metaphysics), while asserting that empirical inquiry is needed to settle just what those laws are.

Kant’s Critique of Pure Reason offers a clear line of exposition through Kant’s first Critique, and by tying that exposition to the problems of the Antinomies of Reason and the ever-present attempt to ask questions we can know we cannot know the answers to, the new student of Kant will be equipped to read the Critique with a roadmap that signals landmarks that Kant’s own exposition sometimes leaves obscured. The book also helps orient the reader to the secondary literature, and throughout it draws on helpful supporting material from Kant’s corpus, including from his letters, his lectures, and his pre-critical work. It is perhaps best suited for an undergraduate course on Kant’s Critique of Pure Reason, though graduate students and philosophers looking for a thorough overview of one of the central themes in Kant’s theoretical philosophy will also benefit from reading it.