Part of the immense success of John Rawls’s A Theory of Justice stemmed from the sense that it showed how rigorous formal models of reasoning could be applied to ethics. In this book, Gerald Gaus continues that tradition, but with a twist. Rather than arguing that formal models can be used to establish an ideal theory of justice, Gaus employs social choice models to demonstrate our lack of the precise knowledge required for the specification of ideally just social conditions to orient the search for improvements in justice here and now. Along the way to this conclusion, in admirably clear prose, he sympathetically but critically introduces his readers to post-Rawlsian contemporary political philosophy, interweaves the history of utopian political thought, and ends by suggesting how we might construct a public social world not governed by ideal theory but rather acceptable to diverse perspectives, despite the intractable and deep disagreements that characterize the exercise of human reason under free institutions. Thus, Gaus has produced a rich, challenging, and at times brilliant book, one that strives to put forth a vision of what political philosophy may and may not do to advance human freedom.

Drawing on Amartya Sen’s The Idea of Justice, in addition to Karl Popper’s critique of utopian political thought in The Open So