Abstract

Morality, it is commonly argued, cannot be extreme in the demands it makes of us, because “ought” implies “can”, and normal human psychology places limits on the extent to which most of us are capable of devoting our lives to the service of others. To evaluate this argument, we need to distinguish different uses of “ought” and “can”. Having distinguished these uses, we find that there is more than one defensible version of the principle that “ought” implies “can”. However, these distinctions can also be deployed to show that the attempt to argue from this principle to the conclusion that morality cannot be extremely demanding fails.