A Thinker's Tool Box

In his new book, philosopher Daniel Dennett explains how to attack big questions like the nature of consciousness and free will

There are two kinds of philosophers, says Daniel Dennett: the usual kind and what he calls anti-philosophers, those whose first response to the field’s classic conjectures is often a kind of outrage, accompanied by an impulse to “knock heads and straighten people out.”

Dennett, the Austin B. Fletcher Professor of Philosophy and co-director of the Center for Cognitive Studies, is clearly a deep-dyed anti-philosopher. He recalls that his first episode of philosophical outrage occurred during a college course when he encountered Descartes’ argument that the mind is an immaterial thing separate from the body. “I was sure he was wrong,” Dennett says, “and that I could show why in an afternoon or two. Fifty years later I think I’ve succeeded.”

While tirelessly wrestling with Descartes and other celebrated sages, this anti-philosopher has become a Big Name himself—the New York Times recently described him as “America’s most widely read (and debated) living philosopher.” But he’s never lost his contentious edge, and in his latest book, Intuition Pumps and Other Tools for Thinking (W.W. Norton & Co.), he gleefully detonates a bunch of cherished concepts, including modern Cartesians’ view that the mind can’t be fully explained by science.

The book’s main goal, though, is to provide a kind of how-to manual on the sweet science of knocking heads in philosophy. Dennett says he was inspired to write it by the notion “that it would help if philosophers got more self-conscious about their methods. I saw this as my opportunity to talk about how I do what I do, what works, and what doesn’t.”

The book’s main goal: To provide a kind of how-to manual on the sweet science of knocking heads in philosophy.

In 77 short chapters, some only a page long, he lays out assorted tools of persuasion, such as reductio ad absurdum (zeroing in on an argument’s hidden self-contradictions), and what he calls “intuition pumps,” thought experiments designed to provoke “table-thumping” agreement.  

A few are familiar, such as Occam’s razor (keep explanations as simple as possible). Others are common tricks he illuminates with witty labels, such as “deepities,” apparent profundities that really aren’t—“Love is just a word,” for example. Deepities get a wrench on our minds, he explains, by ambiguously implying things that are both trivially true and vacuously cosmic-sounding.

Like deepities, some mind tools are what Dennett calls “boom crutches”—deplorable aids to obfuscation. One is “Occam’s broom,” the whisking of inconvenient facts under the rug. Pulling no punches, he names an entire category of boom crutches after the late Harvard biologist Stephen Jay Gould, one of his long-time foes on Darwinian issues. A frequently encountered form of “Goulding,” he writes, employs the word “rather” as “a way of sliding you swiftly and gently past a false dichotomy.” Here’s a made-up example he offers to show how this trick works: “It is not that people are mere ‘moist robots’ … it is rather that people have free will, and are morally responsible for their good and bad deeds.”

This statement foists a false either-or, Dennett argues, because there’s no reason that moist robots (as he calls all of us) can’t also possess free will and moral responsibility.

Much of Intuition Pumps concerns specialized persuading devices Dennett has used in earlier books to show that presumably bottomless mysteries—consciousness, free will, the divine—can be reduced to scientific puzzles.

In a chapter titled “Beware of the Prime Mammal,” he offers up a provocative mind twister involving two premises: every mammal has a mammal for a mother, and there have been only a finite number of mammals. These may seem obvious. But consider: the first statement implies that if at least one mammal has existed, there have been an infinity of them stretching back in time, which contradicts the second statement. Thus, if you buy these propositions and want to avoid a contradiction, you must conclude that mammals don’t exist.

The cover of Intuition Pumps and Other Tools for Thinking

Dennett’s point is that it’s a mistake to begin analyzing very complicated things, such as species, by drawing “bright lines” around them that supposedly define their essences—a standard practice among word-fussy philosophers, he notes. The fossil record indicates that a gradual transition occurred as clear reptiles evolved into clear mammals, with many sort-of mammals—and sort-of mammal mothers—along the way. In other words, the first premise is insidiously flawed and misleading.

A lot of philosophizing about the brain is muddied by a similar mistake, he argues. Those who contend that we’re mysteriously more than moist robots, echoing Descartes, tend to draw bright lines separating people’s “real” believing and desiring from the “as-if” believing and desiring of, say, computer chess programs, which can be seen as robotic mini-minds with goals and beliefs about best moves. This leads to the same kind of flawed thinking, he argues, that positing a prime mammal does.

Dennett has aimed at ever broader audiences over the years, most famously, or notoriously to some, with writings during the past decade making the case for atheism. (His biting godlessness has made him the only philosopher I know of who’s received death threats. As he once commented, “There is no polite way of saying, ‘Excuse me, but have you ever considered the possibility that you’ve devoted your life to a fantasy and... [an] institution that does more harm than good?’ ”)

Intuition Pumps promises to widen his reach even further with witty analyses of a whole panoply of fascinating questions. In fact, the book does double duty, serving as an introduction to his entire body of work and acting as a kind of large-scale intuition pump to channel readers toward rigorous lucidity by showing how a master thinker painstakingly parses knotty problems. (Call it Dennetting.)

At 71, Dennett says he isn’t ready to retire. For one thing, he’s too busy pondering the topic of his next book: how evolutionary theory can be applied to culture. And after more than 40 years at Tufts, to which he dedicated Intuition Pumps, he still finds the university a compellingly congenial place to work.

“It has always seemed to be just right,” he writes in the preface, “like Goldilocks’ porridge: not too burdened, not too pampered, brilliant colleagues... [and] good students serious enough to deserve attention without thinking they are entitled to round-the-clock maintenance.” This analogy, by the way, is the book’s very first intuition pump: It clarifies why Dennett, for all his mental ingenuity, can’t seem to get his mind around the idea of resting on laurels.

David Stipp, the author of The Youth Pill: Scientists at the Brink of an Anti-Aging Revolution, is a freelance writer based in Arlington, Mass. 

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