To unmask an idea is to disarm it by claiming that it has been advanced in the service of unacknowledged motives, bypassing the question of whether the idea is true or false. Most of us engage in the occasional unmasking of policy arguments. But unmasking becomes problematic when it is a "turn of mind," a standard tool applied to a wide range of arguments, as in the work of policy writers Deborah Stone and William Riker. This article argues that the unmasking turn of mind misunderstands the world of policy and politics, and poses risks to a society's practice of deliberation on policy matters. Guidelines for responsible unmasking are proposed.