Evolutionary psychology
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From the SL4 Lexicon:
A way of looking at human psychology as the product of a series of Complex Functional Adaptations, most of which evolved while humans led hunter-gatherer lifestyles.
Evolutionary psychologists discount or ignore psychological hypotheses whose veracity relies on the presence of functional adaptations in the human mind that would not have had selection pressures operating in their favor.
To make a general point, I'm going to take a minute to talk about a simple evolutionary argument that does not pertain specifically to human psychology.
An evolutionary argument that you regularly find in discussions of nutrition on the internet concerns the distinction between a fruit and a vegetable. The biologist's definition of a fruit is a plant structure that contains seeds, a.k.a, embryos that will become new plants given the right conditions. It is clear that the reason many plant species have nutritious and brightly colored fruits is so that animals will eat the fruit and thereby carry the seeds away, spreading the species geographically, something that, eg, an apple tree, being stationary, obviously cannot do by itself.
A vegetable, on the other hand, is a part of a plant, eg, a leaf or a stem, that does not bear seeds. (According to these definitions, a tomato is a fruit, so these definitions differ slightly from the folk definitions.)
Now plants have a strong tendency to contain chemicals that are toxic to animals. Biologists believe that this is because those toxins discourage animals from eating the plants. (BTW, it is believed that the liver evolved as a means to detoxify plant material so that the animal with the liver could eat more plant material and a greater variety of plants.)
The argument made by nutritionists is that one should eat fruits rather vegetables because it is the one structure in the plant where it does not help the plant to discourage animals from eating the structure; thus a fruit is expected to contain fewer toxins and more nutrients than other plant structures.
Opponents of evolutionary explanations have pointed out that this is a weak argument because there are many exceptions: fruits which are terribly toxic to humans and vegetables that are not.
And the opponents are right that it is a weak argument in the sense that there are much better ways for you and I to decide what to eat, including the results of billions of dollars of research into the health effects of various commonly-eaten fruits and vegetables.
What the opponents of evolutionary arguments often miss is that if you and I found ourselves on a strange planet without having brought along any food and consequently were faced with the decision of which of the independently-evolved, unfamiliar plant structures to eat, knowing that we risked poisoning ourselves, then selecting fruits over vegetables is a good strategy.
The moral of this little story is that evolutionary arguments tend to be useful in the absence of other good ways of making decisions about a domain or concern.
Evolutionary psychologists tend to believe that this is the current state of the science of psychology: in many important areas of the science, there is simply not any good theory at all. A corollary of this hypothesis is that most of what has been taught in academic psychology departments for most of the 20th Century is poorly-supported conjecture or just plain false.
There are several likely explanations for the general failure of 20th-Century psychology. Here is a quote from Judith Rich Harris:
The science of understanding people is called "psychology." But psychology isn't taken seriously, because most folks think they already understand people--who needs science?
What's worse, this attitude is common not just among non-experts like (begging your pardon) yourself: it's common even among psychologists. They all have their own pet theories of what makes people tick, and if the evidence doesn't happen to agree with their theories--well, to hell with the evidence.
(End of quote.)
Another explanation for the general failure of 20th-Century psychology is the hypothesis that attributing motives and "diagnosing" character flaws has been an important part of the constant reputation-based competition and social maneuvering that has been an important part of human genetic fitness ever since humans evolved social intelligence.
In this hypothesis, just as humans find other aspects of interpersonal competition motivating, humans find it very motivating to speculate on the motives of person X or to persuade person X of the character traits of person Y. Moreover, the particular motives or traits chosen will tend to rely on considerations that are not scientifically useful: eg, people percieved as competitors will tend to get assigned with unflattering motives and traits while persons perceived as friends or allies flattering.
It seems that the science of human psychology is just a bigger nut to crack than, eg, Newtonian-Galilean physics or even relativity and quantum physics were. The field is more complex, and there are more psychological obstacles to perceiving the field accurately. Some believe that with Evolutionary Psychology we are finally making solid gains although there is certainly no broad consensus among psychologists that this is so. In fact, evolutionary psychologists and their admirers are at this time still definitely in the minority.
The best online introduction available can be found at http://www.psych.ucsb.edu/research/cep/primer.html. See also Evolutionary Psychology Resources, Complex Functional Adaptation, Integrated Causal Model, Massive Modularity Hypothesis.
