Kant’s Theory of Action (review)

This significant, stimulating contribution to Kantian practical philosophy strives to interpret Kant’s theory of action in ways that will increase readers’ understanding and appreciation of Kant’s moral theory. Its thesis is that Kant combines metaphysical freedom and psychological determinism: our actions within the phenomenal world are causally determined by our prior psychological states in that world and are appearances of our free action in the noumenal world. McCarty argues for a metaphysical, “two-worlds” interpretation of Kant’s transcendental distinction between appearances and things in themselves over epistemological or methodological “two-standpoints” interpretations familiar from Christine Korsgaard and Henry Allison (along the way, McCarty also challenges Allison’s “Incorporation Thesis”). Some of the book’s arguments are textual, displaying perceptive readings of Kant’s lecture notes, published works, and philosophical influences. Others primarily concern the philosophical plausibility or moral tenability of various positions one might attribute to Kant. The book’s greatest strength is McCarty’s positive account of Kant’s theory of action. He presents a coherent, even elegant, two-worlds model. His interpretations of maxims, incentives, empirical character, and Gesinnung are insightful.

The book’s first two chapters introduce McCarty’s understanding of maxims and incentives and begin tackling what he calls “the problem of justification and explanation.” Chapter 3 defends the claim that Kant embraced psychological determinism. Chapters 4 and 5 present McCarty’s two-worlds interpretation of the transcendental distinction, defend it from objections, and argue for its superiority over two-standpoint interpretations. Chapter 6 focuses on moral motivation, presenting respect for the moral law as an incentive capable of explaining morally justified actions, and distinguishing between morally worthy and virtuous action so as to defend Kant’s ethics from common objections. Chapter 7 similarly disentangles notions of a good will and virtue, provocatively claiming that all human agents have both a good will and virtue. The main task of chapter 7, however, is analysis of the radical evil in human nature. Chapter 8 raises questions about Kant’s conception of the highest good—particularly, the afterlife in which we are to continue our moral progress—as an object of rational hope.

I read the book’s main argument as follows:

1. 1. Kant’s theory of action must solve “the problem of justification and explanation”: it must show how the reasons that justify a judgment that one ought to do something can also explain one’s doing it. Kant’s theory of action must solve this problem because if what justifies an action cannot also explain it, such justification is “irrelevant.” Only if our actions are explicable in terms of practical reasoning is justification of action by practical reasoning (e.g. by reference to hypothetical or categorical imperatives) “relevant” to our conduct. The problem of justification and explanation arises as it does within Kant’s ethics because Kant holds that pure reason is capable of issuing in action; yet he also holds that human beings and other imperfectly rational agents do not invariably act as we recognize we ought. So we cannot explain our acting as we ought (when we do) simply by appeal to “ought implies can,” internalism, or “the causality of freedom.”

2. 2. Psychological determinism, combined with a metaphysical interpretation of Kant’s transcendental distinction, allows Kant to solve the problem of justification and explanation. Through a timeless, free act in the noumenal world, we each fix our empirical character, which serves as the “causal law” for our actions in the phenomenal world. Maxims, which function as both major premises in practical syllogisms and rules of our empirical characters, provide bases for both the imperatival justifications and motivational explanations of human actions. The “logical force” of a maxim justifies action on it; the “psychological force” of the maxim—specifically, of the incentive incorporated into the maxim—explains action on it.

3. 3. Psychological determinism is compatible with and beneficial for Kant’s moral theory. Most crucially, it is compatible with the freedom necessary for moral agency and responsibility.

4. 4. Two-standpoint...