On Deep Rationality

This is a response to Deep Rationality: The Evolutionary Economics of Decision Making

In this article, Kendrick et al. try to explain various forms of “irrationality” by appealing to what they are calling “deep rationality”. The basic point is that standard rationality requires that we maximize our expected utility – we do the action which, given the various probable results, is likely to yield the greatest overall value to us. We often fail to do this, in various predictable ways, and so the standard claim is that we are irrational in various predictable ways. But, say the authors, these actions do, in fact, make sense, if one looks at them the right way, and so these actions aren’t actually irrational after all.

The reason that these actions are irrational, on the standard view, is that they bias some decisions over others. For example, when a person is risk-averse, that person prefers $20 over a gambling coin toss in which heads yields $40. Rationally, these two options are the same, but to the risk averse person the $20 safe option is preferable, so to that extent the person is seen as irrational. According to deep rationality, this preference is in fact rational in some way, because a risk-averse strategy (for some contexts) will maximize “fitness” (roughly, the number of offspring or kin).

One of the successes of the article are the number of different examples in which the way we make decisions changes based on context. If a person is in “mating mode”, her attitude towards risk is different than when in “status mode”. That’s really interesting to me – decision making strategies are not, then, fixed in all contexts. This means that personalities are, to some extent, contextual.

It also seems somewhat successful in using evolutionary psychology to try to explain some of the results that we see, in which people are irrational in various ways. I’m in general skeptical of evopscyh, because I don’t think we know enough about what life was actually like during the evolutionary past, and I worry that we just make up stories about it to fit the narrative we want. However, the stories they tell here make some sense, and go some way to explaining why we would behave the ways we do in these contexts, despite the irrationality of the actions and attitudes.

Least successful to me is the idea that this evolutionary perspective constitutes a type of rationality. Being able to explain a behavior doesn’t make it rational, even when you use a term like “deep rationality” to try to make a distinction from regular old rationality. One could explain a criminal’s criminal behavior by discussing how terrible his home life used to be, but that doesn’t make the behavior any more rational, only explicable. Behaving in the ways they are talking about isn’t rational in any sort of standard sense – it doesn’t accomplish the agent’s goals in the most effective way. Instead, these behaviors accomplish genetic goals. If genes had goals, and could pick a strategy for the organism that carries them around, then they would pick the behavior. But that’s a far cry from claiming that the organism itself is rational in any way, especially “deeply”.

One might think I’m just quibbling on language. But it matters, because we care about being rational. And the fact is, even if being risk averse is explicable by genetic factors, one should still try to stop being risk averse, because it predictably will lead to worse results for you. In other words, insofar as talking about rationality is prescriptive and trying to help people make decisions, we should be encouraging them to drop the “deeply rational” behaviors in favor of actual rational behavior.