Imagine you are in a helicopter above Los Angeles without a chart and want to fly to Reno, Nevada.  In what direction would you fly? Of course, it is a trick question. Reno lies to the west of Los Angeles.  There are many similar paradoxes:  Edinburgh is located west of Liverpool, Rome east of Venice.  Our mistaken answer illustrates the fallibility of human judgment.

Or does it?  Get real..  Anyone in a helicopter above Los Angeles without a chart and wanting to fly to Reno, Nevada is a fool and should to lose his pilot’s licence.  The usual way to go from Los Angeles to Reno is to take Highway 5 north to Sacramento and then turn east, as you would expect, on Highway 80.  

If you were in a helicopter above Los Angeles without a chart, you would be well advised to follow a similar route.  Not just because pilots without navigational aids are often advised to use major roads for guidance.  If you attempted to fly directly to Reno you would collide with Mount Whitney.

What we keep in our heads is not the actual map of California, or Britain, or Italy, but a stylised, simplified map organised around a north-south, east-west grid:  and the stylised map is actually more useful to route planners than a truer representation.  Juan Luis Borges told the story of the competition to produce the most perfect map:  the winner was completely useless because the most perfect map is a full size reproduction of the world.

The helicopter pilot is the signature example of one of the earliest of the growing stream of books about our supposed irrationality which assert that our analytic skills are poor and our judgment faulty.  But if we really are ‘predictably irrational’, why does this behaviour persist?  Perhaps evolution is smarter than the authors of these books.

When people read quickly ‘a bird in the the hand’

many omit the redundant ‘the’.  But who is making the mistake?  Is it the subject, trying to make sense of a silly task, or experimenter, who devised the silly task to elicit the mistake.  The practical skill of making sense of statements that do not say exactly what the writers intend is useful even if it sometimes leads us astray.

Should we conclude from optical illusions that we should eschew our judgment of space and distance in favour of careful measurement and calculation?  Perhaps, but if we did, we would find it difficult to walk down the street, far less drive a car.  Our judgment of speed and distance, though fallible, is also remarkable.  The most sophisticated optical equipment with extensive computing capability struggle to replicate the performance of a small child, and does not stand comparison with a cat or a fly.

Analytic skills are neither necessary nor sufficient for good operational performance, as the many barely articulate Olympic medallists demonstrated.  The Wason test is a meaningless card game used by experimental psychologists.  Most participants muff it when it is simply a card game.  Faced with the same problem in a practical context, most people master it easily.

These demonstrations of our supposed irrationality mostly involve artificial situations – the helicopter pilot without a chart, the phrase deliberately framed to mislead, in which sensible practical rules that we use to get through the complexities of everyday life give misleading answers.  The skills we inherited from our ancestors and learnt as children are not always appropriate. Mistrust people from other tribes, a useful rule for most of human history, is a distinctive principle in an age of cheap travel and mass migration. But that means we should understand our behaviour better, not discard the evidence of experience.  There were no collateralised debt obligations on the savannahs, or even when I was at school.  But the old rule of don’t eat something if you don’t know what’s in it would have served investors well.  A cheery disposition is often objectively unjustified, but makes life better.  If irrationality is predictable, it probably isn’t irrational.