Thursday, February 24, 2011

I think, therefore I am… misguided

I've just started to reread a book by the Harvard psychologist Steven Pinker, published in 2002.

It's an exceptional book, like all of Pinker's published works, dealing with the time-honored debate between nature and nurture. That's to say: Is the character of a human being determined by his inherited genes, or are we forged essentially by our childhood environment and upbringing? The title of Pinker's book is The Blank Slate. Maybe I should explain to young readers of this blog that, once upon a time, when the Earth was young (before the invention of the iPad), and writing paper was still a relatively expensive commodity, school children used to carry out their class exercises in subjects such as arithmetic and spelling by means of a reusable writing tablet composed of a flat and thin rectangular slab of dark stone, known as a slate.

As Pinker points out, the metaphor of a blank slate is usually attributed to the British philosopher John Locke. The expression itself seems to be a variation on the medieval Latin tabula rasa [scraped tablet]. These days, in everyday French, people use the expression "table rase" to designate the notion of starting from scratch. In monasteries, the tabula was a notice board on which daily chores were associated explicitly with the various monks. So, a tabula rasa was a notice board that was momentarily empty.

In view of its title, Pinker's book on the nature/nurture debate seems to be begging the question, since the blank slate metaphor represents the nurture viewpoint that a baby's brain is relatively empty before being metamorphosed by the acquisition of experiences from the surrounding environment, including above all the people around him, which form his personality, character, intelligence and all the rest. On the contrary, Pinker's book defends the nature viewpoint, in the sense that he considers that human babies are born with a lot of their future intellectual resources already "wired in". In other words, he argues against the theme expressed by his title. At first sight, this is a little confusing for the reader. It's as if the author of a book in support of atheism (such as The God Delusion by Richard Dawkins, for example) were to have chosen whimsically a religiously-oriented metaphorical title such as, say, The Great Ship of God, before going on to liken it to the Titanic.

Pinker introduces several other celebrated metaphors, always in a negative sense. That's to say, he carefully explains these metaphors, and then spends the rest of his book demolishing them.

One of Pinker's earliest targets is dear old René Descartes. Throughout the western world, everybody loves him, because he told us that a human being is a very special hunk of meat equipped with a mysterious thing called a mind. That's to say, a human being is a tandem affair. On the one hand, each individual has a body. And at the same time, he has a mind, which might be thought of as "driving" the body, in much the same way that a person drives an automobile. Now, that's an idea that cannot fail to flatter us, because it's a bit of a bore being stuck with the vulgar hardware, the meat, devoid of an explicit and essentially autonomous self, a mind, indeed a soul. Descartes describes differences between the two collaborators, which might be likened respectively to a nice fresh apple and a hard billiard ball.

I'm not suggesting that Descartes liked apples or played billiards. These objects are merely proposed as a convenient way of looking at Cartesian dualism. Descartes distinguished the two entities by means of a criterion of partial destruction. An individual can lose a part of his body—an arm or a leg, say—just as easily as you take a slice out of an apple. On the other hand, it's practically impossible to cut a billiard ball into slices. Today, nobody likens the human mind to an indestructible billiard ball, because we've heard so much about schizophrenia and so-called split personalities. There are even spectacular cases of patients whose cerebral hemispheres function separately.

A new metaphor for the Cartesian mind was invented by the British philosopher Gilbert Ryle, who referred to it as the ghost in the machine, which seems to be a modernized variation on the ancient "deus ex machina" theme.

During the 18th century, the philosopher Jean-Jacques Rousseau invoked the theme of a wise and pristine creature, untouched by the vices of civilization, whom he designated as the noble savage, whose slates had seen no evil, heard no evil, and spoken no evil. And explorers in the Pacific often imagined that they had come upon such human tribes. But they were inevitably disillusioned before long.

Against the backdrop that I've just sketched, Pinker's task in The Blank Slate is frankly revolutionary, for he attempts to present conclusions—those of the computational theory of the mind—that are often totally astounding. Here's a typically-succinct paragraph in which Pinker employs a wonderful but little-used concept, consilience, which my Macintosh dictionary defines as "an agreement between the approaches to a topic of different academic subjects, especially science and the humanities".

History and culture, then, can be grounded in psychology, which can be grounded in computation, neuroscience, genetics and evolution. But this kind of talk sets off alarms in the minds of many nonscientists. They fear that consilience is a smokescreen for a hostile takeover of the humanities, arts and social sciences by philistines in white coats. The richness of their subject matter would be dumbed down into a generic palaver about neurons, genes and evolutionary urges. This scenario is often called reductionism, and I will conclude the chapter by showing why consilience does not call for it.

I agree entirely with Pinker's precise summary of the situation. On countless occasions, when I've attempted to defend a purely scientific worldview in various human domains, I've encountered immediate accusations of reductionism… often disguised in polite phrases such as "Science can't explain everything" or "You're forgetting the spiritual dimension of our existence". And when I try to affirm that science should be able to explain everything, or that an expression such as "the spiritual dimension of our existence" is fuzzy to the point of being meaningless, many people assume immediately that I'm a dull-witted crackpot with no sensitivity for humanism and culture. Worse, they see me as a misanthrope who has deliberately turned himself away from the real pulsating world of people.

Pinker was courageous to tackle the gigantic challenge of demolishing beliefs in a blank slate, which he designates as "the modern denial of human nature". For me, it's a joy and an easy task to follow Pinker's presentation of the current situation… but that's merely because I agreed entirely with his outlook even before my first encounter with his book. On the other hand, I don't know to what extent a firm believer in the blank-slate concept would be swayed by such a densely-written book. And I fear that even my humble blog post is likely to appear to certain readers as confused mumbo-jumbo.

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