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Why Transitivity Violations Can Be Rational
ananyo writes "Organisms, including humans, are often assumed to be hard-wired by evolution to try to make optimal decisions, to the best of their knowledge. Ranking choices consistently — for example, in selecting food sources — would seem to be one aspect of such rationality. If A is preferred over B, and B over C, then surely A should be selected when the options are just A and C? This seemingly logical ordering of preferences is called transitivity. Furthermore, if A is preferred when both B and C are available, then A should 'rationally' remain the first choice when only A and B are at hand ... But sometimes animals do not display such logic. For example, honeybees and gray jays have been seen to violate the Independence of Irrational Alternatives, and so have hummingbirds ... Researchers have now used a theoretical model to show that, in fact, violations of transitivity can sometimes be the best choice (original paper) for the given situation, and therefore rational. The key is that the various choices might appear or disappear in the future. Then the decision becomes more complicated than a simple, fixed ranking of preferences. So while these choices look irrational, they aren't necessarily."
If your wife reads Slashdot this little game could end quite badly... never get between a woman and her chocolate!
One of my pet peeves with discussions on evolution is the assumption, in general, that any given trait or behavior evolved for a particular reason, or that any one concept such as "logical rationality" can explain the whole evolution of a single such trait. In fact this sounds more like intelligent design than evolution. It's an interesting exercise to track a trait through evolution, but there's a fine line between that and presupposing that every behavior must occur due to some underlying logic.
We're talking about behavior that evolved due to an absurd amount of chaos; how was it not obvious that a "decision becomes more complicated than a simple, fixed ranking of preferences"? And who gets to decide what's "rational"... from a basic evolutionary perspective, anything that has evolved to this point and is still alive and kicking is doing well; it's almost impossible to call any such evolution "irrational", so finding ways to prove it so is just silly. I mean, there's plenty of evolution that seems odd... flightless birds, blind species with eyes, animals that eat their young and their mates... but these species all survive and procreate and carry on from one generation to the next. Why does everything have to be nice and tidy... what's the obsession with "rational"? In fact, the behavior described in the article sounds more rational than the opposite... consider Pandas, who exist almost entirely on one food (bamboo)... these animals are very nearly extinct due to this behavior (some people assert that they would be if it weren't for human efforts to save them). Is that rational from an evolutionary perspective?
I'm sure I sound annoyed, but some times we try to oversimplify things way too much. happy_place is correct; competition could matter, and individual preference clearly exists all over the place... why does there have to be a rationalization? Is it an evolutionary benefit that happy_place likes dark chocolate while their wife hates it? More likely it's just a quirk of evolution, not a grand result of evolution having evolved precisely so that our species won't starve when cocoa is the last remaining food on the planet.
Let me put it this way... given whole of evolution, I would wager that for any categorization of traits that are well defined (such as "rational"), there exists at least one example that is both in and out of that category. SOMETHING has evolved irrationally, oddly, stupidly, and without purpose, due only to quirks of evolution that didn't really get in the way of a species survival, but didn't necessarily help it along either.