It is widely accepted that planning operates at the interface of knowledge and action. As an activity concerned with intervening and taking action to realize better place-based outcomes than would be achieved otherwise, one might assume that the better informed such judgments are, the better the resulting outcomes are likely to be. But how does (and should) knowledge about the world get turned into actions designed to make the world a better place? This article develops a framework to examine the intellectual and practical questions at the heart of the relationship between is and ought.