Korsgaard is wise:

If only the economists who try and read normative requirements right off their theories, as well as unreflective folks who think that the Coase theorem solves all available questions, could be made to read this:

According to a theory very fashionable in the social scientific and economic literature, sometimes called the self-interest or economic theory of rationality, it is rational for each person to pursue his overall good: to act on some variant of the principle of prudence. Many people who believe the self-interest theory of rationality think that they also believe the theory that all practical reasons are instrumental. This combination of ideas is incoherent. The instrumental principle says nothing about our ends, so it is completely unequipped to say either that we ought to desire our overall good or that we ought to prefer it to more immediate or local satisfactions. The self-interest theory of rationality, because it is committed to the principle of prudence, has to go beyond the instrumental theory. Now how could the purveyors of this theory make such an obvious error? I believe the answer lies in what I have just said. People who hold this theory assume that what a person ‘really wants’ is her overall good, and therefore that her ends, her real ends, just are the things that are consistent with or part of her overall good. The standard move is to treat the possibility that someone might desire something inconsistent with her overall good as if it were an uninteresting little piece of theoretical untidiness like the possibility that she might miscalculate or make a mistake. [...] The fans of morality could just as well stipulate that what we ‘really want’ are things consistent with love and respect for everybody, and then they too could claim that we don’t need to go beyond instrumental rationality. Nothing is gained by such devices.

From “The Normativity of Instrumental Reason.”


One Response to “Korsgaard is wise:”

  1. Isak Says:

    I don’t see the problem – your assumptions don’t always have to be 100% all of the time for your model to be useful. For example, if you ask a physicist to calculate how long it will take for a certain object to fall to the ground, he may assume no air resistance. That assumption is wrong, there is in fact air resistance, but it turns out you get close to the same answer most of the time anyway, and the calculation is much, much simpler.

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