Rational Irrationality

For some time now I have been arguing that concepts are polysemous, which is to say that they have multiple meanings. I derive this claim from the common usage of terms, which seem to be referring to the same thing and yet have distinct, even conflicting meanings. I have argued that this is not always a case of mere homonymy but evidences the deep ambiguity of language and even thought. Nevertheless I need not press that strong claim in most cases, since the practical upshot may be the same either way: No matter whether due to homonymy or polysemy, ambiguity abounds, and it is often helpful to dispel it by the careful explication of what one means, that is, of how one is using a particular word.

            Thus my general preface to the topic of this essay, which is rationality. I have already written much about what this concept means in its various meanings. See especially “What Is It to be Rational?” Right now I want only to add a peculiar case (which itself no doubt has several forms), namely, when it is rational to be irrational. This is already fairly obvious in general. For example, if it turned out that people who reason illogically are happier and better citizens than those who reason logically, then it would seem obvious that it is rational (in some sense) to be irrational (in some sense).

            But a particular form of this struck me this morning. I have begun to take a multivitamin. It then occurred to me to wonder whether it was important to take the vitamin at a certain time of day or under certain conditions. I Googled these questions and learned that, indeed, one is advised to take the vitamin in the morning, with food, and in clear water, not hot, not milk or tea or coffee, etc. The reasons were also given.

            Now, as a rational person, which I pride myself on being (albeit far from perfectly!), I would not only be interested in the reason for a course of action, but also be prepared and even motivated to take the action (and hence actually perform the action, all other things equal) once I was convinced of the reasons. However, in this instance I decided to ignore some of the prohibitions and take the vitamin in the morning with a hot drink and not pure water. Does this mean I was acting irrationally?

            Of course, on one account of irrationality, it does indeed. But the point I want to make in this essay is that there is a significant sense in which my decision and action were and are perfectly rational. The key is that my considerations included my own motivations. For I find drinking a glass of water in the morning to be distasteful, and even having tried it, in an act of willing myself to do the rational thing, I realized, knowing myself, that I simply would not be able to persist … or persist to the point where this would become a reliable habit, at least under my present and foreseeable circumstances. Therefore if I became convinced that the multivitamin would do me good, I might very well just stop taking it.

            But, I reasoned further, no doubt the multivitamin would still do me some good. Therefore, I concluded or decided, I would just go ahead and take the vitamin with a warm drink.

            This strikes me as rational. But an objector would argue that the whole point of practical reasoning is to bring our decisions and motivations into conformity with reason. So what sense could it possibly make to allow an irrational motivation to decide what is rational?

            My answer is that an agent’s motivational makeup is just as much a part of the world, and of the set of considerations relevant to some decisions, as anything else. To ignore the reality of oneself would be irrational. There is nothing special about oneself, unless one harbors the myth of having a transcendent ego that is capable of willing things outside the causal stream.

Therefore Q.E.D.