If consequentialism is understood as claiming, at least, that the moral character of an action depends only on the consequences of the action, it might be thought that the difficulty of knowing what all the consequences of any action will be poses a problem for consequentialism. J. J. C. Smart writes that in most cases..

Objective consequentialism is often criticized because it is impossible to know which of our actions will have the best consequences. Why exactly does this undermine objective consequentialism? I offer a new link between the claim that our knowledge of the future is limited and the rejection of objective consequentialism: that ‘ought’ implies ‘can’ and we cannot produce the best consequences available to us. I support this apparently paradoxical contention by way of an analogy. I cannot beat Karpov at chess in (...) spite of the fact that I can make each of many series of moves, at least one of which would beat him. I then respond to a series of objections. In the process I develop an account of the ‘can’ of ability. I conclude with some remarks about the bearing this attack has on subjective consequentialism. (shrink)

This paper argues for the existence of a fourth positive generic value relation that can hold between two items beyond ‘better than’, ‘worse than’, and ‘equally good’: namely ‘on a par’.