The book explores rationality and normativity through a picoeconomic model of dynamic preference reversals and Ainslie’s personal-rule approach. Focusing on negotiations between time-defined selves, it addresses key philosophical issues related to self-control and decision making over time. It primarily addresses a challenge to Ainslie’s approach: how to justify the bundling relation behind personal rules. Bundling links a series of similar choices, each of which predicts the direction of all subsequent ones. The book offers a thorough defense of bundling, examining it from various perspectives. The discussion engages with important contemporary thinkers in the fields of rationality, morality and personal identity, including Elster, McClennen, Gauthier, Bratman, Mele, Nozick, Davidson and others. A central feature of this study is the attention paid to certain neglected aspects of normativity, such as cognitive bootstrapping. This involves making normative leaps to beliefs that connect consequential concerns with long-term reality checks. This book will appeal to researchers and students of rational choice theory, philosophy of action, philosophical psychology and philosophy of economics.