Jackson on Weakness of Will

Abstract

In a paper published in this journal, Frank Jackson develops an account of weakness of will that is interesting for at least two reasons. 1 First of all, in an ingenious way Jackson makes use of decision theory to provide a criterion for action that is the issue of a desire that has 'not evolved in accordance with the agent's reason', and argues that this is a criterion that picks out what we naturally describe as cases of weakness of will. The second reason is that Jackson's procedure takes place under assumptions about the relation between desire and action that are pretty straightforwardly Humean. Jackson's aim is indeed to show 'that clear sense can be made of weakness of will in terms of agents' acting against the dictates of their reason' from a basically 'Humean position about reason and desire'. This feature of the project is of particular interest given that on a Humean view reason is the slave of the passions, so that it does seem reason and desire cannot conflict. Jackson's account holds out the promise of making sense of weakness of will within a model of the mind according to which it is usually thought weakness of will is well-nigh unintelligible, but which is simple, well-understood, and on independent grounds seems plausible. A third feature of Jackson's position which bridges the other two is this. The background to his positive account of weakness of will is a certain treatment of wanting. Jackson claims that this treatment has the double merit of providing a solution to the problem of how weakness of will is compatible with a Humean view of action, and of '(enabling) a relatively straightforward account of features of wanting that are otherwise hard to understand'. Thus the treatment of weakness of will is impressively wedded to the solution of other problems in the philosophy of mind and action. In this commentary, however, I shall not consider this source of merit of Jackson's account. I begin with a resume ofJackson's position. I shall follow this with some counterexamples; and end with a diagnosis of why the problems with Jackson's account arise. Underlying the account is the 'intuitively appealing idea that how much I want something depends in part on what I think is likely or probable if that something obtains'. He goes on to give an example: