The aim of Kant's Order of Reason is to give an account of Kant's conception of rational agency that clarifies and explains both the scope and nature of such activity, and elucidates the centrality of Kant's account of rational determination for his mature critical philosophy. In this book, Colin McLear highlights that the core Kantian insight concerning rational determination is that the capacity for rationality is based in and derived from the capacity for exercising a very specific kind of causality in the world—namely, free, or controlled, causality.

The book consists of three parts. In the first McLear provides a historically contextualized but nevertheless rigorous metaphysical framework for understanding Kant's conception of mental activity, his theory of freedom, and its importance for understanding his conception of the difference between rational and non-rational forms of activity. He then argues that Kant has a control-centered or "enkratic" account of rational activity and agency. According to this view, control is the central and essential aspect of all rational activity, and a rational being is one that can exercise her diverse powers, or use her diverse intellectual faculties, in a manner that is under her own control. Building on this structure, in part two McLear shows how Kant applies his conception of controlled activity to the various forms of activity of which the rational mind is capable, in increasing order of complexity (i.e. attention, conception, judgment, inference, and comprehension). And in the final section of the book, McLear applies this account to longstanding disputes regarding self-consciousness, reason, evil, and alienation.