The Introduction summarises the core themes of the book and outlines how the argument will proceed over the course of its chapters. It explains why the issue it centres around – namely, how the law grapples with the impact of mental disorder on decision-making – is so important, and why successfully navigating the tension between respect for (and deference to) idiosyncratic values, and protection from disorder or impairment, must be a precondition of England and Wales adopting ‘fused’ mental capacity and health legislation, or a more CRPD-compliant statutory framework. It also explains how the book relates to the existing literature in this area, which has focused in recent years on concerns about the binary nature of the capacity framework, and on the individualistic and rational ‘liberal subject’ on which this framework rests. Finally, it elaborates briefly on some of the concepts which the book will draw upon, in particular what is meant by ‘values’ and ‘beliefs’.