 The most influential reply to  BKDA  is to say that, when I acquire evidence that I don’t have hands, such evidence makes me cease to know that I have hands. On this view, when I acquire such evidence, the argument above is sound. But prior to my acquiring such evidence, (4) is false, and so the argument above is not sound. Thus, the truth of (4), and consequently the soundness of this argument, depends on whether or not I have evidence that I don’t have hands. If I do have such evidence, then the argument is sound, but of course it has no general skeptical implications: all it shows that I can’t know some fact whenever I have evidence that the fact doesn’t obtain (versions of this view are defended by Harman 1973 and Ginet 1980).