If you find yourself “fatigued” by all our recent talk of ego depletion – the discovery that self-control essentially functions like a muscle – I don’t blame you. The reason for all the hubbub is the release of Roy Baumeister and John Tierney’s book, Willpower, which renowned Harvard psychologist Steven Pinker reviewed in this past Sunday’s NY Times. His take is pretty similar to ours, believe it or not, that the book (and accompanying research) represents a helpful re-conception of willpower, one that largely rejects the “free” part of modern notions of “free will.” As Pinker also notes, Baumeister and Tierney are on less solid ground when they get into self-help territory and espouse strategies for honing/toning/maximizing willpower. But certainly as a reality check, however unfashionable, about the limits of agency when it comes to both ourselves and others (i.e. that none of us can save ourselves), their book is to be welcomed with open arms.

In experiments first reported in 1998, Baumeister and his collaborators discovered that the will, like a muscle, can be fatigued… Baumeister tagged the effect “ego depletion,” using Freud’s sense of “ego” as the mental entity that controls the passions.

Together with intelligence, self-control turns out to be the best predictor of a successful and satisfying life. But Baumeister and Tierney aren’t endorsing a return to a preachy puritanism in which people are enjoined to resist temptation by sheer force of will and condemned as morally irresolute when they fail. The “will” in willpower is not some mysterious “free will,” a ghost in the machine that can do as it pleases, but a part of the machine itself. Willpower consists of circuitry in the brain that runs on glucose, has a limited capacity and operates by rules that scientists can reverse-engineer — and, crucially, that can find work-arounds for its own shortcomings.

Readers of “Willpower” are treated to triumphs of self-control, like the singer Amanda Palmer (in her first career as a living statue) and the endurance artist David Blaine, along with crash scenes like Oprah Winfrey’s yo-yoing weight and Eliot Spitzer’s hotel-room entertainment. The disasters reveal a limitation of the muscle metaphor: certain evolutionarily prepared drives seem to withstand even the most bulked-up powers of will. The authors note that people with the highest levels of self-control are only slightly better than average at controlling their weight, and they describe disturbing experiments that confirm the old saying “When the penis stands up, the brains get buried” (it sounds better in Yiddish).

Baumeister and Tierney [do not] worry enough that their theory, without some precision about the relevant time spans, can be stretched to explain anything: when people resist one temptation but not another, it’s because their egos have been fatigued by exercise; when they resist temptations across the board, it’s because their egos has been strengthened by exercise. [ed note: sound familiar?!]