"Ought," "Can," and Practical Reasons

by Clayton Littlejohn


Many accept the principle that states that "ought" implies "can":

OIC: S ought to Φ only if S can Φ.

As intuitive as OIC might seem, we should acknowledge that the arguments offered in its support often do not warrant the sort of confidence many of us have in the principle. For example, friends of OIC often say that the principle is needed to explain certain linguistic behaviors. Suppose Smith sees Jones sitting in a chair and Jones tells Smith that he has just been robbed. "You ought to call the police," says Smith. When Jones tells him that he cannot because he has been tied to the chair, it is natural for Smith to recommend some alternative course of action. The reason, some say, is that in learning that Jones cannot get out of his chair to call the police, Smith learns from this alone that his initial remark was mistaken. In saying, "You ought to ask someone to help untie you," he recommends an alternative course of action and tries to correct his first remark.