Debates on the practical relevance of ideal theory revolve around Sen's metaphor of navigating a mountainous landscape. In *The Tyranny of the Ideal*, Gerald Gaus presents the most thorough articulation of this metaphor to date. His detailed exploration yields new insight on central issues in existing debates, as well as a fruitful medium for exploring important limitations on our ability to map the space of social possibilities. Yet Gaus's heavy reliance on the navigation metaphor obscures questions about the reasoning by (...) which ideal theories are justified. As a result, Gaus fails to notice the ways in which his theory of the Open Society resembles the ideal theories he aims to dismiss. Ironically, Gaus winds up neglecting the ways in which the Open Society might tyrannize our efforts to realize greater justice. (This article is part of a symposium on Gaus's *The Tyranny of the Ideal*.). (shrink)