Monday, February 04, 2008

The Superbowl, David Hume and Global Warming

Why were the Patriots so heavily favored to win the Superbowl? Of course, they're a very good team, but let me suggest that part of the answer was an inductive fallacy. The Patriots came into the game undefeated. However, they won some of their games---including their playoff games and their final regular-season game against the Giants---by small margins. Had a few balls bounced differently, they might not have been undefeated; indeed, they might not even have been in the Superbowl.

Nonetheless, bettors and pundits looked at the 18-0 record and thought that it was almost a law of nature that, even if the score was going to be close, the Patriots would win. Why? Because that's how it worked out in all of their previous games this season. And there you have the inductive fallacy. As the great Scottish philosopher (and more) David Hume explained in the 18th century, the past never predicts the future, except if one assumes that the future will continue to be like the past, and there is no basis for that assumption other than the assumption itself (i.e., the past has predicted the future in the past).

Hume was not, however, a nihilist. In many ways, he was the father of modern science. And so the rational response to the problem of induction is to look for patterns and explanations that explain why the past has been the way it has, and then ask whether those patterns continue. To be sure, this answer depends on notions of causality that Hume also critiqued, but practical-minded people can take a more practical lesson from Hume: You need a reason to think that the future will be like the past. In the case of the New England Patriots, it's fair to say that the reason they won so many of their close games was some combination of toughness under pressure and luck. Given that the Giants, of late, had also shown toughness under pressure, good empiricists should have expected that the game had a decent chance of going either way, i.e., that luck would determine the outcome. As indeed it did. Had Eli Manning---not generally known for his scrambling skills---not somehow slipped away from that near-certain sack, the Patriots probably would have won the game.

Inductive fallacies are most dangerous when applied to non-linear phenomena. Part of what has thus far made many Americans resistant to calls for serious efforts to curb greenhouse gases, I suspect, is the apparent evidence of their senses. We've been pouring CO2 into the atmosphere for decades and yet they don't see that much change. And that's because global warming depends on feedback loops that reach tipping points. E.g., Siberian permafrost melts, releasing greenhouse gases and reducing reflectivity, thus increasing heat absorption, leading to higher temperatures, leading to more permafrost melting, and so on. The phenomenon starts out slowly, and no one pays much attention until the effects are dramatic, by which point it's too late.

Jared Diamond's book Collapse provides numerous historical examples of whole societies not noticing how they're destroying their natural environment until the present dramatically stops being like the past. By that point, it's typically too late to change.

Is it a hopeful sign or utterly pathetic that as his prize for winning the Superbowl MVP, Eli Manning received a gigantic Cadillac SUV that happens to be a hybrid?

Posted by Mike Dorf