Additive Theories of Rationality: A Critique

Abstract

“Additive theories” of rationality, as I use the term, are views that hold that an account of our minds can begin with an account of what it is to perceive and desire, in terms which do not presuppose any connection to the capacity to reflect on reasons, and then can add an account of the capacity for rational thought as an independent capacity to “monitor” and “regulate” our believing-­‐on-­‐the-­‐basis-­‐of-­‐perception and our acting-­‐on-­‐the-­‐basis-­‐of-­‐desire. I show that a number of prominent recent discussions of rational perception and action are committed to an additive approach to rationality, and I argue that this approach faces two basic difficulties, each of which is structurally analogous to a classic problem for Cartesian dualism. The Interaction Problem concerns how capacities conceived as intrinsically independent of the power of reason can interact with this power in what is intuitively the right way. The Unity Problem concerns how an additive theorist can explain a rational subject’s entitlement to conceive of the animal whose perceptual and desiderative life he oversees as “I” rather than “it”. I argue that these difficulties give us reason to reject the additive approach, and I sketch an alternative, “transformative” framework in which to think about the cognitive and practical capacities of a rational animal.