  Hudson (2001: 39–44) draws out a surprising consequence of the over-population solution as applied to people. Assume that there are really millions of people just where we'd normally say there was exactly one. Call that person Charlie. When Charlie raises her arm, each of the millions must also raise their arms, for the millions differ only in whether or not they contain some borderline skin cells, not in whether their arm is raised or lowered. Normally, if two people are such that whenever one acts a certain way, then so must the other, we would say that at most one of them is acting freely. So it looks like at most one of the millions of people around Charlie are free. There are a few possible responses here, though whether a defender of the over-population view will view this consequence as being more counter-intuitive than other claims to which she is already committed, and hence whether it needs a special response, is not clear. There are some other striking, though not always philosophically relevant, features of this solution. To quote Hudson: