Okay, okay: it's a terrible phrase. (In my defense, I didn't coin it. Philosophers of science have been kicking it around for a while.) But if "The Pessimistic Meta-Induction from the History of Science" is cumbersome to say and difficult to remember, it is also a great idea. In fact, as the "meta" part suggests, it's the kind of idea that puts all other ideas into perspective.

Here's the gist: because so many scientific theories from bygone eras have turned out to be wrong, we must assume that most of today's theories will eventually prove incorrect as well. And what goes for science goes in general. Politics, economics, technology, law, religion, medicine, child-rearing, education: no matter the domain of life, one generation's verities so often become the next generation's falsehoods that we might as well have a Pessimistic Meta-Induction from the History of Everything.

Good scientists understand this. They recognize that they are part of a long process of approximation. They know that they are constructing models rather than revealing reality. They are comfortable working under conditions of uncertainty — not just the local uncertainty of "Will this data bear out my hypothesis?", but the sweeping uncertainty of simultaneously pursuing and being cut off from absolute truth.

The rest of us, by contrast, often engage in a kind of tacit chronological exceptionalism. Unlike all those suckers who fell for the flat earth or the geocentric universe or cold fusion or the cosmological constant, we ourselves have the great good luck to be alive during the very apex of accurate human thought. The literary critic Harry Levin put this nicely: "The habit of equating one's age with the apogee of civilization, one's town with the hub of the universe, one's horizons with the limits of human awareness, is paradoxically widespread." At best, we nurture the fantasy that knowledge is always cumulative, and therefore concede that future eras will know more than we do. But we ignore or resist the fact that knowledge collapses as often as it accretes, that our own most cherished beliefs might appear patently false to posterity.

That fact is the essence of the meta-induction — and yet, despite its name, this idea is not pessimistic. Or rather, it is only pessimistic if you hate being wrong. If, by contrast, you think that uncovering your mistakes is one of the best ways to revise and improve your understanding of the world, then this is actually a highly optimisticinsight.

The idea behind the meta-induction is that all of our theories are fundamentally provisional and quite possibly wrong. If we can add that idea to our cognitive toolkit, we will be better able to listen with curiosity and empathy to those whose theories contradict our own. We will be better able to pay attention to counterevidencethose anomalous bits of data that make our picture of the world a little weirder, more mysterious, less clean, less done. And we will be able to hold our own beliefs a bit more humbly, in the happy knowledge that better ideas are almost certainly on the way.