WEAKNESS OF THE WILL
9. 1. WEAKNESS of will is discussed by philosophers mainly in connection with disputes between adherents of internalism and their opponents, the externalists (see Chapter 8). Substantially the same dispute divides advocates of prescriptivism from descriptivists. According to prescriptivists and internalists, in the sense in which the term is here used, one cannot hold a moral or other evaluative opinion without prescribing or desiring that it be acted on, or being motivated to act on it oneself if one is the subject of it. To descriptivists and externalists this has seemed obviously false ( Ewing 1959; ch. 1). The existence of cases in which people (the weak-willed or acratic) think that they ought to be doing something but are not disposed to do it seems an obvious objection to prescriptivism and internalism.
On the other hand, there is a problem for externalists and descriptivists too. For if there were no connection between the thought that one ought to do something and the disposition to do it, there would be no puzzle about weakness of will; but there clearly is a puzzle. If someone does not do what he (or she) says he thinks he ought to be doing, an explanation is called for. The person who says 'Yes I ought. So what?' is thought to have something wrong, not merely with his morals, but with his understanding of morality (of the word 'ought'). The only way to sort out these problems is by a careful analysis of the different contexts and the different senses in which we can say 'I ought' but not do what we say we ought, in order to determine whether there are any cases which impugn one or other of the two positions. Such an analysis might leave each side in possession of part of the field, and resolve one of the central problems in ethical theory. But it has not yet been achieved.
9. 2. The problem first arose when Socrates, as reported by Plato (e.g. Prot.352 ff.) and Aristotle ( EN 1145b25), denied the possibility of akrasiā or weakness of will. All these philosophers were in part____________________