As is usual with correlations (playing chess <=> your brain goes bonk), it is not clear which way the causality goes, if at all. It could be that playing chess at the highest levels affects the mind in negative ways; it may be that abnormal minds are more likely than others to be attracted by the game; or it could simply be that the correlation is spurious, i.e. non-causal.
Shenk does not take sides on this debate, but he does report the pronouncements of a number of Freudian psychoanalysts on the matter. For instance, Ernest Jones (Freud’s biographer and protege), confidently stated that “It is plain that the unconscious motive activating [chess] players is not the mere love of pugnacity characteristic of all competitive games, but the grimmer one of father murder.” What?? That’s right, it’s the good ‘ol Oedipus complex -- itself rooted in the all-encompassing Freudian explanation for human behavior, sex drives -- that pushes players to protect their Queen (=mother) and checkmate the King (=father). Here is some more nonsense from Jones (p. 147 of Shenk’s):
“It will not surprise the psychoanalyst when he learns ... that in attacking the father the most potent assistance is offered by the mother (=Queen). ... It is doubtless [its] anal-sadistic feature that makes the game so well adapted to gratify at the same time both the homosexual and the antagonistic aspects of the father-son contest.” (Never mind that the Queen was introduced relatively late as a chess piece, as Shenk’s history shows.)
Jones wasn’t the only one to psychobabble about chess. Here is American psychologist and Freud disciple Isador Coriat (again, quoted in Shenk, p. 148): “The sole object of the game for these individuals was to render the King (the father) helpless through checkmate, that is, castrate him. The winning of the game produced a feeling of intense pleasure, as a checkmate was unconsciously equated as a castration revenge.” And finally, psychoanalyst (and chess master) Reuben Fine: “[the game] certainly touches upon the conflicts surrounding aggression, homosexuality, masturbation and narcissism. ... [The King] stands for the boy’s penis in the phallic stage, and hence rearouses the castration anxiety characteristic of that period.” Wow, so what does it mean that I enjoy chess only on an occasional basis? That I’ve gotten over my phallic stage, that I’m not sufficiently homosexual, or that I decided that castrating my father wouldn’t be such a pleasure after all?
The point is that these quotes perfectly illustrate why Karl Popper thought that Freudian psychoanalysis is a pseudoscience: it’s no so much that the above is not true (though I very much doubt it is), but that there is not a single shred of evidence that would count for or against such statements. They are, to use Popper’s phrase, unfalsifiable.
The unfalsifiability of psychoanalysis in turn stems from the human facility at telling stories. It is much, much easier to invent an explanation for something than to do the hard work of actually testing whether the alleged explanation actually holds up to the empirical evidence. Heck, often it is even hard to figure out what empirical evidence could possibly bear on the issue to begin with!
Which brings me to evolutionary psychology, a discipline of which I’m about as fond as psychoanalysis, and for similar reasons. Like in the case of psychoanalysis, the problem is not that the basic ideas aren’t sound: sex surely is a fundamental drive of human urges and emotions, and therefore must play an explanatory role in a variety of human behaviors, just like psychoanalysts would have it. Likewise, evolutionary psychologists are certainly correct that natural selection must have played a role in shaping human behaviors and cognitive abilities, as general evolutionary theory would predict. The trouble starts when we get to detailed scenarios aiming at accounting for individual instances. The case of chess briefly described above is an example of how pompously confident psychoanalysts can be of their explanations (“It is plain that...”, “It will not surprise...”, etc.) even though they would be hard pressed to propose an empirical test of what they take to be so self-evident.
Similarly, when evolutionary psychologists like Randy Thornhill and Craig Palmer claim that rape is an adaptive strategy employed by inferior human males, or when Steven Pinker tells us that all we need to do to understand the human mind is to “reverse engineer it,” they may be correct, but most of their statements are in fact completely unfalsifiable, and therefore -- in the Popperian view (which does have its own problems, to complicate the matter) -- simply not scientific. For instance, to seriously test the rape-as-adaptation hypothesis one would have to know something about the following: a) what was the frequency of rape in ancient human populations; b) the average benefits of the behavior (i.e., number of successfully fathered offspring) vs. the likely costs (e.g., being clubbed to death by the woman’s relatives); c) some details of the social environment of Pleistocene human populations, to assess the possibility of frequency-dependent selection favoring rape, the evolutionary mechanism invoked by Thornhill and Palmer. Failing this, one would want at least to have d) a large sample of species phylogenetically close to humans in which we had data on the frequency and success of rape, for purposes of historical comparison. Needless to say, we have no clue to any of the above. And please note that the other obvious route, studying rape in current human societies won’t do either, because today’s social environment is presumably dramatically different from that of the Pleistocene, so that even if one could show a current adaptive value of rape (which is hard to imagine, by the way) one would still not have made the evo-psych case.
As for Pinker, the case is more complex because he addresses nothing less than the totality of human cognitive abilities, not a single aspect of human behavior. I do think Pinker is likely to be correct that at least some human cognitive abilities are the result of natural selection, but it is easy to make the case that they cannot all be. For instance, one can advance a plausible argument (but, importantly, no more than an argument, i.e., lacking any empirical evidence) that some mathematical ability may have been advantageous to early humans. Perhaps it was necessary to keep track of the group members' hunting scores to insure a fair division of the catch (see how easy it is to come up with a just-so story?), or whatever. But even Pinker, I hope, wouldn’t dream of suggesting that natural selection is responsible for our brain’s ability to solve differential equations -- which is what brought us to the moon and allows much modern technology to work. If I am correct in this, then at the very least the explanatory scope of evolutionary psychology is much more limited than its supporters have been trumpeting for a while.
Allegedly, even Freud once said that sometimes a cigar is just a cigar. Evolutionary psychologists hardly ever admit to the possibility of other explanations for human behaviors, and when they do, they are still clearly confident that they got the big picture right, despite the almost ridiculous paucity of evidence in their favor. OK, enough of this, I need to go back to my chess game; I haven’t managed to castrate my father yet...