Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Revenge of the Nerds 157But let's say that A causes B, and B in turn causes the protagonist of A tomake a copy of itself—let's call it AA. AA looks just like A, so it appearsas if B has caused A. But it hasn't; it has only caused AA, the copy of A.Suppose there are three animals, two with a cloudy lens, one with a clearlens. Having a clear lens (A) causes an eye to see well (B); seeing wellcauses the animal to reproduce by helping it avoid predators and findmates. The offspring (AA) have clear lenses and can see well, too. Itlooks as if the offspring have eyes so that they can see well (bad, teleological,backward causation), but that's an illusion. The offspring have eyesbecause their parents' eyes did see well (good, ordinary, forward causation).Their eyes look like their parents' eyes, so it's easy to mistake whathappened for backward causation.has clear ^~ sees >» reproduces • has clear4 lens well lens/ (A) (B) (AA)/ __ has cloudy ^- sees•V lens badlyV has cloudy • sees> lens badlyThere's more to an eye than a clear lens, but the special power of areplicator is that its copies can replicate, too. Consider what happenswhen the clear-lensed daughter of our hypothetical animal reproduces.Some of her offspring will have rounder eyeballs than others, and theround-eyed versions see better because the images are focused from centerto edge. Better vision leads to better reproduction, and the next generationhas both clear lenses and round eyeballs. They, too, arereplicators, and the sharper-visioned of their offspring are more likely toleave a new generation with sharp vision, and so on. In every generation,the traits that lead to good vision are disproportionately passed downto the next generation. That is why a late generation of replicators willhave traits that seem to have been designed by an intelligent engineer(see figure on page 158).I have introduced Darwin's theory in an unorthodox way that highlightsits extraordinary contribution: explaining the appearance of designwithout a designer, using ordinary forward causation as it applies to replicators.The full story runs as follows. In the beginning was a replicator.