Kant's Incorporation Requirement: Freedom and Character in the Empirical World

In Religion within the Boundaries of Mere Reason Kant wrote that ‘freedom of the power of choice has the characteristic, entirely peculiar to it, that it cannot be determined to action through any incentive except insofar as the human being has incorporated it into his maxim.’¹ This is an obscure statement, in both meaning and provenance. Yet almost all recent interpreters of Kant's practical philosophy find it crucial for understanding his theories of freedom and motivation, since it seems to indicate what we are required to do in order to act by our own free choice. Here I refer to Kant's statement expressing the requirement that incentives be incorporated into maxims as his ‘incorporation requirement.’ How that requirement is best understood will be the leading question in what follows: a question I shall answer by showing why the incorporation requirement, and Kant's theories of freedom and motivation, should be understood differently from the way they are now usually understood.

The Kantian perspective in ethics is perennially subject to criticism for the obscurity of its explanations of freedom and moral responsibility, and for the rigidity of its criterion for the moral worth of actions. Although gifted scholars have written in Kant's defense on these points, I believe present interpretive strategies for responding to these stock criticisms have made matters worse; especially from the perspectives of critics. Recent work on Kant's theory of freedom struggles to come to grips with the determining influence of character that is acknowledged by almost everyone, including Kant himself.² Recent accounts of Kant's theory of moral appraisal propose ad hoc, psychologically implausible models of human motivation designed to allow actions on admirable emotions to qualify as ‘acting from duty,’ in order to merit ‘moral worth.’ By calling attention to an arcane requirement for free choice now considered essential for understanding Kant's practical philosophy, my overall aim here is to push prevailing views of his theories of motivation and moral appraisal toward positions more conciliatory to those of critics. To this end, in what follows, I shall be emphasizing moral responsibility for character, not just for action, and moral admiration for virtue, not just for moral worth.

John Silber may have initiated recent interest in the incorporation requirement, almost fifty years ago.³ Not long afterward, and for the next couple of decades, John Rawls began emphasizing it in his influential lectures on Kant's practical philosophy.⁴ Gerold Prauss found the requirement interpretively fruitful in the early 1980s; and by 1990 Henry Allison had labeled the passage from Religion containing the incorporation requirement the ‘Incorporation Thesis,’ hailing it as ‘the centerpiece of Kant's conception of rational agency.’⁵ Recent interpreters still rely on the so-called the Incorporation Thesis, as can be seen, for example, in the work of Christine Korsgaard, Paul Guyer, and the latest work of Allen Wood.⁶ To my knowledge, no one has expressed any doubt about the interpretive adequacy of that Thesis, although Rüdiger Bittner has challenged it on conceptual grounds.⁷ With the possible exception of Silber, all of these interpreters, and many others, have read the incorporation requirement as expressing the view that freely choosing to act is incompatible with being causally determined to act by the impelling forces of desires or incentives.⁸ Two advantages of reading the requirement this way are the following.

First, this reading helps to sharpen the contrast between Kant's rationalist theory of motivation and Hume's empiricist, ‘belief-desire’ model. As Hume's theory has it, we are caused to act always by desires for objects we believe our actions will produce; and when our desires compete, the strongest among them causally determines our choice to act. But Kant's interpreters see the incorporation requirement as telling us, on the contrary, that whenever we act by our own free choice we ‘incorporate’ the desires or incentives on which we choose to act into maxims, making them the reasons for our actions. We therefore act on freely chosen reasons, and we are never...