I offer a novel dispositional reply to Derk Pereboom’s four-case manipulation argument. Drawing on recent work in the metaphysics of dispositions, I argue that manipulated agents’ rational abilities are masked—prevented from manifesting as they otherwise would—by neuroscientists’ manipulation. I argue that masking better explains why manipulated agents are not responsible for their actions than causal determinism does, as we ordinarily take masks to explain why agents are not morally responsible for their actions or inaction. Because causal determinism is not a mask, there is a relevant difference between manipulation and causal determinism, and the four-case argument fails.
