Instrumental desire

Let NORID be the thesis that there is no instrumental desire (NID) or instrumental desire reduces (RID) to non-instrumental desire plus belief about what is a means to what (e.g., an instrumental desire for jogging reduces to a non-instrumental belief that jogging promotes health and a non-instrumental desire for health).

One argument for NORID is something I got from Mark Murphy. Desires explain actions. But if M is a means to an end E, we do not need to posit any desire for M to explain the pursuit of M—all we need to posit is a belief that M promotes E and a desire for E.

Here are two more arguments, perhaps unoriginal.

Argument 1: Inertia. Start with this premise:

1. If x has an instrumental desire for M, then x believes that M is a means to something that x desires.

Suppose I have a non-instrumental desire D for M, which I believe is a means to E and to nothing else I desire, and suppose the desire does not reduce to non-instrumental desire and belief. Now, suppose I lose the belief that M is a means to E. There may be connections between desires and beliefs, but unless the kind of reduction that RID envisages holds, a mere change of belief does not immediately result in the loss of a desire. There is an inertia in the mental life. Therefore, after I have lost the belief that M is a means to E, my irreducible desire for M continues. Moreover, the same inertia makes it plausible that the desire does not immediately change in nature, from instrumental to non-instrumental. (This assumes that the difference is intrinsic. That might be a point worth questioning.) But if so, then for a while I have an instrumental desire for M and no belief that M is a means to anything that I desire. Which contradicts (1).

Argument 2: Rationality. Suppose I am perfectly rational and I non-instrumentally desire E with strength d_E. Suppose I know with certainty that M is a necessary and sufficient means to E. Then, rational as I am, I will be motivated to pursue M at least with strength d_E. Now suppose that I instrumentally desire M with strength d_M. Surely a desire that does not reduce to non-instrumental desire and belief adds to motivation. So, now, I will be motivated to pursue M with strength greater than d_E (maybe d_E+d_M?). But it is irrational to be motivated to pursue a means with a strength beyond one's perfectly rational desire for the end, and that was d_E. So, NORID is true of a perfectly rational being. But it is plausible that NORID is also true of imperfectly rational beings. First, it would be odd if a basic kind of desire—instrumental desire—were never rational. Second, we can say the following. The above argument shows that if I have an irreducible instrumental desire for M, that desire adds to the motivational force of my desire for E combined with my certainty of the necessity and sufficiency of M. But whatever it adds to that motivational force goes over and beyond the merely instrumental motivation for M, since the merely instrumental motivation for M is fully accounted for by the motivation in favor of E combined with my certainty of the necessity and sufficiency of M.

I am grateful to Dan Johnson for showing me that my arguments do not show that there are no non-instrumental desires, but only that either there are none, or they are reducible.