Abstract

Two options are incommensurate in value if neither is better than the other, and if a small improvement or worsening of one does not necessarily make it determinately better or worse than the other. If a person faces a sequence of choices between incommensurate options, she may end up with a worse options than she could have had, even though none of her choices are irrational. Yet it seems that rationality should save her from this bad outcome. This is the practical problem posed by incommensurability of values, and it may be solved by a new account of practical reasoning.