The manifestability argument presented by Papineau and Loewer turns on the premise that nonphysical properties are capable of making a difference to physical conditions. From this and the completeness of physics a strenuous supervenience conclusion is supposed to follow. I argue that the plausible version of this premise implies a weaker supervenience thesis only, one that is too weak to be of any use for a physicalist. There is a more contentious premise one might use to deduce the needed conclusion, (...) but that more contentious premise has no empirical support. (shrink)