Phlogiston. You know the stuff. It was the essence, the secret sauce that made combustion, or fire, be. Problem was, it didn't add anything to the equation of knowledge. As an unobservable and unknown it did not provide explanation. As a substance that predicted everything about fire, it predicted nothing. It just had to be because fire is a remarkable thing, requiring a remarkable cause. In a modern century, it perhaps would have a history, equally remarkable and wholly inferred. The mind entertains the spectre of an evolutionary organic chemist, positing how phlogiston had to be because of why it had to be. A mandate perhaps from nature, selected perhaps because of nature's need to tidy up the detritus of the world in a consuming flame. All well and good, and perhaps a design for the future, except the chemist Lavoisier was not in the plan. Phlogiston's demise was a question not of non-existence, but non-necessity, and Lavoisier got to the heart of the burning question by properly explaining it. So oxygen came ascendent, and a testable theory of combustion took the place of the combustible academic politics that generated heat, but little light.
Lavoisier, thinking about combustion.
In a modern age, we are forgetful of the arguments now long settled that that have riven academic communities. The controversies of the past, from a circular sun in Copernicus' day to the nature of the quantum in the present were settled by explanations, the invariable result of direct observations of the ways things actually are.
As a source of explanations, nature is a relatively easy thing, possessing as it were a one track mind. We can thus rest assured that billiard balls and moons behave accordingly to the same laws, and that the DNA that that makes me is the same stuff that makes men and mice. Unfortunately, human nature is diverse in its uniformities, and reveals itselt in myriad universal patterns that seem unmalleable by experience, and are as fixed in essence as the spark that ignites a flame. These universal sparks are as distinctive and obscure as the phlogiston of old, and assume the metaphor of neural algorithms, instantiated obscurely in the human brain, that are tethered as obscurely to a selfish gene. This of course is the credo of evolutionary psychology. It makes for good story telling, instilling a true life drama into the origins of behavior, or at least, a tall tale twice told of human and gene. Of corse, evolutionary psychologists can and do have it both ways, and merrily posit mental modules to account for every tendency, real or imagined, that humans can generally display. As a leading spokesman for the movement, the linguist Steven Pinker took this dictum to heart, and in his book 'How the Mind Works' spun a web ot tales that crisscrossed the time and circumstance of humanity. The obscure and ancient processes of natural selection were wedded with simple stories of creation that seemed to naive ears to be justly so. A proper marriage of Darwin and psychological science? Not quite. Rather, it was actually a union of Darwin and a consummate story teller, Rudyard Kipling
Darwin and Kipling: The Unwitting Inspiration for Evolutionary Psychology
A scientific story can be tested, but without test, it is a story and no more. For Kipling, the elephant got its trunk because a crocodile pulled on it. Does this mean that elephant trunks occured as an adaptation due to hungry crocodiles? Perhaps, and perhaps not, because it is a hypothesis that cannot be tested. Of course, evoutionary psychologists usually speak in more basic terms, and reduce it all to genes and what serves their survival. But in spite of this microbiological case, the story telling remains the same.
How the Elephant Got its Trunk
Consider the incest taboo. It's a universal constant among humanity. Grow up with partners of the opposite sex, whether kin or not, and sexual maturity will bring a startling indifference to them. The universal experience of growing up immature in the company of kith and kin was bound to a hypothetical 'imprinting mechanism' that like phlogiston explained the incest aversion in all its forms. Of course, the fact that such a specific imprinting mechanism has never been discovered in the human brain, or that such a mechanism provided only post hoc predictions didn't matter. What did matter was that the evolutionary story seemed so compelling. After all, since mating with kin would likely result in children with two heads and twelve toes, evolution in its blind wisdom would surely see to it that we have some inborn mechanism to prevent such non adaptive horrors. Certainly Pinker bought into this line, and the 'just so' story of why natural selection had to build an imprinting mechanism was accepted by him as well as other evolutionary psychologists as bona fide evidence that one existed. That is, the 'why' such a mechanism must be impelled an acceptance of 'how' it must be.
Of course, Pinker did not count on a modern day Lavoisier, nor would he, since the grey congealed pudding that makes up our brains is really not grist for a book on how the mind works. The integration of neuroscience and learning theory is typically avoided by evolutionary psychologists, and particuarly avoided by Pinker. But that's where we find our explanation, as simply and elegantly as Lavoisier's theory of combustion, requiring but a breath of fresh air both figuratively and literally. And so, what is our solution? Perhaps the answer to why we stop short of kissing our sister has to do with stopping short, at a stop sign.
Blocking
Consider how we learn the rules of the road. A red light signifies that traffic must stop, and that other intersecting lanes will move. But what would happen if an equally reliable purple light began after a few seconds to shine above the red light. Would we pay attention to this equally reliable indicator to stop, and would we do so if approaching an intersection in the future, when only a purple light shines before us?
Life is full of traffic signals
Surprisingly, no. The stimulus salience of the purple light would be effectively coopted or 'blocked' by the red light, even though logically it should suggest the same response, namely a foot on the brakes.
The concept of 'blocking' is well established in learning theory, and its neurological correlates have been extensively traced. Its evolutionary significance is obvious, namely, the need to effectively parse the stimuli in the world from the important and novel from the important yet merely redundant. A red light predicts traffic flow, and there is no need to learn to learn the reliability of a different light if the information it conveys denotes no new information. Break the rule and we would be overwhelmed with repetitive associations that only serve to command precious computational space.
Unfortunately, nature's designs do not account for changes in the order of the world. Take away all red lights and leave the purple, and one will have to 'relearn' (and likely the hard way!) the importance of purple lights. Keep the red light and concurrently introduce a green, and we will hesitate as well. The fact that important associations cannot be made if they denote redundant rather then irrelevant information is crucial to understanding many behavioral anomalies that we are too quick to adduce to specialized instinctive causes. More pointedly, why explain that behavior as the result of a specialized neural mechanism when a general purpose mechanics will do? Spend your early years with a relative or friend of the opposite sex, and you will inadvertently learn to associate their appearance with nonsexual intentions, enough ironically to block the sexual desire that comes with maturity. In other words, familiarity breeds not contempt, but apathy! To attribute an evolutionary tale to an inferred mechanism designed to fit the tale is like attributing walking to the store to the evolutionary pressure to pick a dozen eggs when merely the need to be able to walk will do. A specific trait compacted and expressed like a software code is like phlogiston, irrefutable because is unprovable; a sterile solution when a more mundane and eminently provable alternative is all that is necessary. The solution, as Lavoiser would attest involves merely coming up for and with, air. (Rather than coming up with a tale, as Pinker does, which is nothing but hot air!).
