Abstract: This volume is divided into two main parts. The first examines the nature of rationality broadly understood, which is customarily divided into the theoretical and the practical. Whereas theoretical or epistemic rationality is concerned with what it is rational to believe and sometimes with rational degrees of belief, practical rationality is concerned with what it is rational to do, or intend or desire to do. Included in part I are discussions of practical and theoretical rationality and the relations between them; the relation between reasoning and rationality; rationality as internal consistency; rationality and morality; formal methods in the study of rationality (Bayesianism, decision theory and game theory); rationality and emotion; rationality and rule-following; procedural and substantive rationality; internalism and externalism about practical reasons; Humean rationality; Kantian rationality; motivated irrationality; and paradoxes of rationality. Part II explores rationality’s role in and relation to other domains of inquiry: psychology, gender, personhood, language, science, economics, law, and evolution.

Keywords: externalism, Hume, internalism, irrationality, Kant, morality, motivation, practical, rationality, reason, theoretical