Metasemantic security arguments aim to show, on metasemantic grounds, that even if we were to discover that determinism is true, that wouldn't give us reason to think that people never act freely. Flew's [1955] Paradigm Case Argument is one such argument; Heller's [1996] Putnamian argument is another. In this paper I introduce a third which uses a metasemantic picture on which meanings are settled as though by an ideal interpreter. Metasemantic security arguments are widely thought discredited by van Inwagen's [1983] (...) Martian Manipulation objection. I argue that van Inwagen's objection, if right, can be parodied to undercut metasemantic arguments which aim to show that deliverances of physics do not tell us that no objects are solid. A diagnosis of where the parody objection breaks down against the pro-solidity argument is then used to resist the objection as applied to the Ideal Interpreter Argument. I go on to defend the argument from the charge that it relies on a ham-fisted version of interpretivism. (shrink)