 The desert basis has already been discussed in  section 2.2:  a certain kind of wrong. The focus of the discussion at this point is on two puzzles about the existence of a desert basis. The first puzzle concerns how humans, given the fact that our choices are grounded in our brain activity, and that our brains are parts of the physical world, can have the sort of free will necessary to deserve punishment at all. The second puzzle concerns why, even if they deserve punishment, that fact should make it permissible for anyone to take on the role of giving them the punishment they deserve.