“Ought Implies Can” as a Principle of the Moral Faculty

This thesis is a contribution to moral psychology, the systematic study of the cognitive processes underlying moral judgment. It has two main aims. First, it attempts to show that the so-called Linguistic Analogy (LA) is the most productive framework for the study of moral cognition. As its name suggests, LA has it that moral psychology can be fruitfully modelled on linguistics, in particular on the Chomskyan project of detailing the architecture of the Language Faculty (FL)—a domain-specific cognitive system dedicated to language. This means, amongst other things, that the fundamental task of moral psychology is to discover and detail the representations, principles, and computational operations of the Moral Faculty (FM)—a domain-specific cognitive system that underpins the human capacity for moral judgment. Second, the thesis argues that the “Ought Implies Can” principle (OIC)—according to which if an agent ought to perform an action, then she can perform that action—is one of the central principles of FM, and proposes a novel account of how OIC is implemented in FM. To achieve this second aim, the thesis presents novel empirical evidence on intuitive moral judgments of ordinary people and argues that the best explanation of these data is to consider OIC as a processing constraint on the operations of FM.