Tuesday, December 15, 2009

scientific proof

Perhaps it's time to once again point out that "scientific proof" is a red herring. As any number of science's theoreticians have carefully explained over the years, scientific methods rarely if ever actually "prove" anything. Rather, science works mostly with a double-negative approach: An accepted theory is one that we have failed to disprove. Scientific testing and data collection is mostly aimed at showing that a hypothesis is wrong. Results that agree with a hypothesis are generally called "support", not "proof", because usually the tests can't provide proof. But a single (correctly done;-) test or observation is often sufficient to disprove a theory.

This is why scientific theories are often called "tentative". Scientists are always trying to think of new ways to test a theory, and sometimes they succeed in finding situations where a theory fails. The poster child for this was the failure of Newton's mechanics to explain a number of anomalous observations about a century ago, which led to Einstein's theories explaining how the universe actually works. Of course, his theories have never been "proved", either. They have merely withstood hundreds of new experimental tests. Tomorrow some physicist (or high-school student) may produce a new test that demos an exception to Einstein's equations. But until then, they are accepted not because we've proved them, but rather because we have repeatedly failed to disprove them.

Of course, fundamental physics is "easier" that climate in an obvious way. Weather is much more complex than things like particle physics or orbital mechanics, which can be reduced to some fairly simple equations (though not quite as simple as we thought back in Newton's day). Anything dealing with weather has to be treated statistically, since the complexity is far beyond the capacity of our most powerful super-computers. (Our computers can't even model a butterfly's wings in detail, much less the effect the butterfly has on weather halfway around the world.;-) Since the public is generally totally ignorant of statistics, it's not surprising that people would fail to understand what the AGW theorists are telling us. It's fairly obvious that even most of the posters here in this "nerd" community don't understand the difference between weather and climate. You don't have much of a chance of understanding the issue without a good grounding in statistical methods, in addition to all the kinds of chemistry that you have to understand.

But the constant use of forms of the words "prove" and "proof" in regard to scientific theories should be treated with humor, since such words are an open statement that the author doesn't know much at all about scientific methods. Those are media and propaganda terms; they have very little use in scientific discussions. Proofs are what mathematicians do. Scientists do disproofs. (And it is interesting how well the radically different approaches of math and science complement each other. So far I haven't read much enlightening from either camp on this topic, just the observation that they play well together. But we all know that.)

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