Rationality

Is "you should..." synonymous with "it is rational for you to..."?

Comments

Some philosophers would derive the former from the latter--Kant, for example, is generally supposed to think that obligation derives directly from rationality. But I think it is going to depend upon what specific notions of responsibility ("should") and rationality are at work. I think a good way to see how a negative answer to your question might work is to ask a different version of your question: Is it self-contradictory to say that one shouldn't always be rational, or to say that one should (sometimes) be irrational?

For example, if one supposes that morality is wholly a social construct, and without any basis in reality beyond social convention (I don't believe this, but some do), then it seems to me that one might recognize duties imposed by whatever conception of morality was currently fashionable that seemed (and indeed were) irrational. But that is only if one does not also think that the principles of rationality are social constructs. Usually, however, those who think that morality is a social construct also think that all values (including rationality) are social constructs. Or, if one takes a Romanticist view of rationality (regarding it as something like cold calculation), one might say you shouldn't always be rational. Famously, in the area of religious belief, Kierkegaard argues the the "knight of faith" was one who held religious beliefs in ways that were opposed to rationality.

In most ethical systems, however, I think that, even if obligation and rationality are not treated as the same thing, they are biconditionally related, which is to say that whenever you have one, you will also have the other.

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