'ought', 'can', and Practical Reasons 1

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. 3 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. If only it were this simple. Some chalk this up to conversational implicature. In discovering that his advisee cannot follow his advice, his offer of additional advice is proper because when we say someone ought to perform such and such an action, we would violate conversational maxims if we advise someone to perform an action knowing they will not follow this advise. 4 Although the details of such proposals have been criticized, it is unlikely that we need OIC to explain Smith's linguistic behavior. 5 Let us change examples. Having untied Jones, Smith heads with Jones to the hardware store. In addition to getting new locks for his doors, Jones had promised his mother that he would spruce up the place. 'You ought to buy some tile for the kitchen and leave the living room as is', says Smith. Jones says that he is unwilling to leave the living room walls the same drab color they are now. 'In that case, you should paint the walls yellow', says Smith. As before, it seems that Smith will advise a new course of action in learning something about Jones. In the previous case, learning that Jones is incapable of leaving his chair leads Smith to advise Jones to call for assistance, creating the appearance that he has taken back his original advice having recognized that it was mistaken. Having urged him to call the police initially, he advises him instead to ask someone to …