Monday, February 29, 2016

Student Spotlight: Intrinsically Irrational Instrumental Desires

I had always assumed that only ultimate ends, or telic / final / non-instrumental desires, could be intrinsically irrational.  (Think Future Tuesday Indifference.)  Instrumental desires, by contrast, may happen to be irrational if based on a false and irrational means-end belief, but then the problem is extrinsic to the desire itself -- the problem instead lies with the false belief, and one could presumably imagine circumstances in which the means-end belief would be true, thus making the instrumental desire in question a perfectly reasonable way of achieving one's goals.

Or so I assumed. (And I think it's a fairly common assumption.)

University of York undergraduate philosophy student Lorin Thompson (mentioned here with permission) drew my attention to an interesting class of counterexamples.  We can obtain intrinsically irrational instrumental desires if we consider instrumental desires that are essentially self-defeating.  His example is the "desire to think of a number, in order to not think of a number (simultaneously)."  The implicit means-end belief -- that one can achieve avoiding thinking of a number, by means of thinking of a number -- is logically incoherent, and the resulting instrumental desire is thus intrinsically (rather than merely extrinsically) irrational.

It's a cool case!  At the very least, I'll need to re-write my essay question for future years to ask something like whether there are "unworthy" ultimate ends rather than just "intrinsically irrational desires", as it now turns out that even Humean subjectivists should make room for the latter.

Does anyone know whether such cases have been discussed before, or could it potentially be a new contribution to the literature if Lorin were to write up his paper for an academic journal?


  1. Hi Richard (/Lorin),

    Can I hear a bit more about the supposed case? Is the desire a desire with the content [to think of a number in order to avoid thinking of a number]? Or is the content of the desire [to think of a number], where this is held on the basis of a prior desire [to avoid thinking of a number] and the belief [that I can avoid thinking of a number by thinking of a number]? I think you mean the latter, but I'm not 100% sure.

    In the former case: If one thinks that there is nothing wrong with desiring the impossible ("if only pi were even!") then it might seem that there's equally nothing wrong with desiring to [think of a number in order to avoid thinking of a number]: this is just a desire, that sadly, it's impossible to satisfy.

    In the latter case: I think Humeans will deny that this desire is *intrinsically* irrational: there's nothing intrinsically wrong with desiring to think of a number (so the Humean says). It's true that this desire was formed irrationally, but that's because of the underlying belief, and not intrinsic to the desire.

    But, of course, I might be missing something or else misunderstanding the case.


    1. Yeah, it'd be interesting to hear more from Lorin on this point. Personally, I tend to think of instrumental desires as complex states combining telic desires with means-end beliefs in the right way. The means-end belief is thus an intrinsic component of the instrumental desire, rather than something external that merely gives rise to it. But even on this picture, the Humean could reasonably comfortably take the case on board by noting that it's the belief-component rather than the telic-desire component of the complex instrumental desire that is ultimately at fault here.


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