Elliott Sober has a longstanding interest in delimiting the epistemic (as opposed to pragmatic or aesthetic) relevance of parsimony considerations. He tells us in his marvelous new book, Ockham’s Razors, that his goal “is to determine when parsimony is relevant and when it is not. It is obvious that simple theories may be beautiful and easy to remember and understand. The hard problem is to explain why the fact that one theory is simpler than another tells you anything about the way the world is” (2). This is a ferociously difficult problem—and although it lies at the heart of much of contemporary philosophy of science and epistemology, it is embarrassingly often complacently shirked rather than confronted. Few philosophers have worked so hard, judiciously, and productively on the problem as Sober has—and Ockham’s Razors provides an invaluable synthesis and overview of this work.