"The Limits of Reason" in Newsweek

Newsweek just published an article called "The Limits of Reason: Why evolution may favor irrationality", by Sharon Begley.  It's a good article explaining many cognitive biases and fallacies with good concrete examples.

However, I note with some amusement that Begley got this bit wrong.

Consider the syllogism “No C are B; all B are A; therefore some A are not C.” Is it true? Fewer than 10 percent of us figure out that it is, says Mercier.

But the syllogism is wrong!  The syllogism is correct if we assume that there exist some B.  So what if B is unicorns?  Then the syllogism doesn't necessarily work:

No mammals are unicorns (because there are no unicorns).
All unicorns are horses (all existing unicorns anyway, which is to say none).
Therefore some horses are not mammals.

Begley continues...

Interestingly, syllogisms are easier to evaluate in the form “No flying things are penguins; all penguins are birds; so some birds are not fliers.” That’s because we are more likely to argue about animals than A, B, and C.

...Also because we know penguins exist.

But back on topic.  Sharon's main point is that evolution favors irrationality.  This is true.  It's a well-documented fact that humans have some irrational cognitive biases.  This irrationality must have been favored by evolution; nearly all of our biological traits are there because they were, in some sense, favored by evolution.  Empirical fact.

The explanation for why evolution favored irrationality is somewhat more suspect.

Failures of logic, he and cognitive scientist Dan Sperber of the Institut Jean Nicod in Paris propose, are in fact effective ploys to win arguments.

This explanation just raises so many questions.  Does irrationality help you persuade other people, or does it help other people persuade you?  If the latter, doesn't this require some sort of group selection?  What exactly is the mechanism connecting persuasiveness to evolutionary adaptiveness?

In general, I'm pretty suspicious of these evolutionary psychology narratives, because it's difficult to prove one narrative over another.  And yes, there are other narratives.  For instance, Michael Shermer often explains confirmation bias by saying that for early humans, it was more advantageous to mistake the wind for a tiger than mistake a tiger for the wind.  Come to think of it, does Shermer have any evidence for this narrative aside from its initial plausibility?  Another alternative hypothesis is that cognitive biases are not adaptive at all; a flawed brain was just the best that evolution could manage.

Which of these hypotheses, if any, are true?  I cannot imagine any evidence that would distinguish between them.  I wish popular explanations of evolutionary psychology would focus more on the kind of evidence they use, because whatever it is, it'd have to be really clever.  Believe me, I get that scientific evidence can often be really hard to explain to lay people, but this could be downright fascinating, almost too clever to exist.