Suppose, as biocentrists do, that even microorganisms have a good of their own – that is, some objective form of welfare. Still, human welfare is vastly greater and more valuable. If it were infinitely greater, individualistic bio-centrism would be pointless. But consideration of the facts of evolutionary history and of the conceptual relations between infinity and incommensurability reveals that there are no infinite welfare differences among living things. It follows, in particular, that there is some very large number of bacteria (...) whose aggregate overall welfare is not less than the welfare of a human being. (shrink)