Wednesday, September 30, 2009

Smith on Parfit 5 of15: The Rationality of Desires

In this series of posts I am commenting on an article sent to me by a member of the studio audience. These are, in a sense, notes written in the margin as it were as I highlight passages in the article and explain my agreement or disagreement.

The next phrase that I highlight for comments is this one:

For example, it isn't relevant to what reasons an agent has that (say) he is so constituted that he will acquire an intrinsic aversion to spiders the very first time he ever sees one. Evolutionary considerations might well afford an explanation of why all agents are so constituted, but, even if they did, that wouldn't suffice to show that it is rational for agents to respond to the perception of spiders by acquiring such an intrinsic aversion.

My scribbling here asks:

How do we answer the question of whether it is rational for agents to have a fear of spiders?

You cannot look at the fear of spiders alone and answer any question as to whether or not it is rational to have such a fear. What would make the fear of spiders good or bad? Perhaps the fear gives you reason to avoid where spiders are found, which helps to keep you alive given that many spiders are poisonous. Perhaps, instead, it is a far that keeps you frantically searching your house for signs of a spider and going into convulsive fits when finding one.

You can only ask whether the fear of spiders tends to fulfill or thwart other desires. If the fear of spiders tends to fulfill other desires (e.g., by preventing us from getting poisoned), then we have reason to promote such a fear. If it tends to thwart other desires (by deterring us from actions that would fulfill other desires), then we have reason to be rid of or at least weaken such a desire.

Which brings up the question of whether we can do so.

We tend not to evaluate the desires of an agent as being rational or irrational unless they are desires over which a person has some amount of choice. If somebody where to cut into us to remove an inflamed appendix, we do not ask about the rationality of an aversion to the sensations generated by that act. It would be better for the patient if she did not have that aversion. Yet, it is not irrational pain. It is, instead, merely a brute fact.

It might be useful to imagine a new hospital that has decided to employ Parfitian anasthtics. Parfitian anesthetics involves giving a patient all of the relevant facts explaining why the patient has reason to be indifferent to the sensations generated by the medical procedure she is about to undergo. Realizing that she has no reason to react to those sensations with aversion, and many and strong reasons not to, means that it would be irrational for her to respond to those sensations negatively. Those aversions do not account as legitimate reasons for action. Do they, then, not count as legitimate reasons to ask for chemical anesthetics?

Ultimately, question of the rationality of desires do not seem to be about the rationality of desires at all, but the rationality of actions that have the capacity to change our desires. Where we have reason to believe that an agent has some measure of choice over whether to be afraid of flying, or of closed spaces, or of public speaking, we call a fear irrational if a rational agent would act so as to rid himself of that fear.

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