On Philosophy

September 11, 2006

Rational Desires

Filed under: Ethics,General Philosophy — Peter @ 12:16 am

A few days ago I discussed what is required for a belief, in general, to be rational (in summary: that there is a reason to believe it, where the reason is taken to be an objectively valid reason). If we desire to be rational people this may be useful advice, but there is more to life than beliefs, there are also desires. (In fact desires are probably more important than beliefs on average, since beliefs by themselves don’t lead to action.)

Unlike beliefs, desires don’t seem to require reasons to support them, I don’t need a reason to desire chocolate ice cream, I simply desire it. Here I will characterize all desires as the urge to bring about some state of affairs, which in the example mentioned above would be me eating chocolate ice cream. In general we defend rationality as something to be desired because it leads to good results, for example if you have rational beliefs then you are most likely to be correct (and I think we can all agree that correctness is something we should aim for). We could describe a collection of desires as irrational then if having those desires made it more difficult to being about the desired states of affairs. For example, if I also desire to lose weight then my collection of desires, to both eat chocolate ice cream and lose weight, could be called irrational since pursuing them both interferes with the very results that I desire. It can even be the case that a single desire is irrational. For example, if we could establish that striving to be happy made one unhappy (this probably isn’t always the case, but let’s say it is for the sake of the example) then the desire to be happy would be irrational, because by desiring to be happy we prevent ourselves from achieving happiness.

This is all well and good when it comes to individual desires, and there are a wide range of desires that can all be considered rational under this view. However, problems arise when we consider interactions between the desires of many people. For example, let us consider the desire that things go as best as possible for me. Certainly this seems like a desire that could be considered rational. But when we have a group of people, who all desire the best for themselves, and they attempt to accomplish some goal that requires cooperation, the results may be worse than if they were selfless. This is not artificial example, it’s something that happens in real life on a regular basis. Consider a team of people attempting to design a better car. It is true that if one of them slacks off they will still be paid the same, but the individual who slacks will be better off, since they had to work less for the same amount of money. However, if everyone on the team desires the best for themselves they will all slack off and will all be paid less (since the result is noticeably worse).

Scenarios such as this one are part of a family called prisoner’s dilemmas. I won’t go into more detail about them here, since they have been well studied by other philosophers and mathematicians, but the accepted conclusion is that no matter how the self interested individuals reason the result will be worse in these cases than if they were selfless. (For example, if they spend effort in order to prevent the others from slacking they may prevent the failure of their project, but they had to waste energy implementing this solution, that a group of selfless people could have done without.) So, if a group of people all have that desire it is self defeating, and hence irrational. What makes this case interesting, however, is that it is not self-defeating when others are selfless.

Now we can’t say that because this desire, that things come out best for oneself, is irrational sometimes that it is irrational all the time, since my desire to lose weight is not irrational by itself, but is irrational when accompanied by a desire to eat chocolate ice cream. To resolve the rationality of this desire in general we need to introduce an additional principle: that having a desire causes those around you to be more likely to have that same desire. You can think of it as peer pressure or social custom if you wish. Now I don’t have the evidence to claim conclusively that this principle about desires is universally true, but it certainly seems plausible. For example, if you see one person wearing a dog as a hat you won’t be very likely to do the same, but if everyone is doing it you will probably feel some urge to do the same, even if you still reject the practice for other reasons. And if this principle is correct then it does make wanting what is best for oneself irrational, since you having that desire encourages others to have it, which in turn results in outcomes being worse for you.

Of course this doesn’t mean that the only rational alternative is to be completely self-sacrificing. There are numerous other possible desires, such as desiring what is best for everybody, including oneself, or wanting the best for other people, but giving oneself some priority. I will leave the analysis of the rationality of these claims as an exercise for the reader.


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