Understandably, some commentators have worried about the problem of deviant causation, and whether Locke has an answer to it (e.g., Lowe 1995: 122–123; Yaffe 2000: 104; Lowe 2005: 141–147). The problem is that if I let go of a climbing rope, not as a direct result of willing to let it go, but as a result of being discomfited/paralyzed/shaken by the volition itself, then my letting go of the rope would not count as voluntary even though it was caused by a volition to let go of the rope. The solution to this problem, if there is one, is to claim that, in order for an action to count as voluntary, it is not sufficient for it to be caused by the right kind of volition: in addition, it is necessary that the action be caused in the right way (or non-deviantly) by the right kind of volition. Spelling out the necessary and sufficient conditions for non-deviant causation is a steep climb. Chances are that Locke was no more aware of this problem, and was in no better position to answer it, than anyone else was before Chisholm (1966), Taylor (1966) and Davidson (1980) brought it to the attention of the philosophical community.