Os limites da ciência

terça-feira, setembro 14, 2010

THE LIMITS OF SCIENCE

Plenty of today’s scientific theories will one day be discredited. So should we be sceptical of science itself? Anthony Gottlieb explains ...

From INTELLIGENT LIFE Magazine, Autumn 2010

Good sense is the most fairly distributed commodity in the world, Descartes once quipped, because nobody thinks he needs any more of it than he already has. A neat illustration of the fact that gullibility seems to be a disease of other people was provided by Martin Gardner, a great American debunker of pseudoscience, who died this year. In the second edition of his “Fads and Fallacies in the Name of Science” (1957), Gardner reported that most of the irate letters he received in response to the first edition criticised only one of its 26 chapters and found the rest to be fine. Needless to say, readers disagreed about which chapter was the faulty one. Homeopaths objected to the treatment meted out to themselves, but thought that the exposé of chiropractors was spot on, and vice versa.



No group of believers has more reason to be sure of its own good sense than today’s professional scientists. There is, or should be, no mystery about why it is always more rational to believe in science than in anything else, because this is true merely by definition. What makes a method of enquiry count as scientific is not that it employs microscopes, rats, computers or people in stained white coats, but that it seeks to test itself at every turn. If a method is as rigorous and cautious as it can be, it counts as good science; if it isn’t, it doesn’t. Yet this fact sets a puzzle. If science is careful scepticism writ large, shouldn’t a scientific cast of mind require one to be sceptical of science itself?

There is no full-blown logical paradox here. If a claim is ambitious, people should indeed tread warily around it, even if it comes from scientists; it does not follow that they should be sceptical of the scientific method itself. But there is an awkward public-relations challenge for any champion of hard-nosed science. When scientists confront the deniers of evolution, or the devotees of homeopathic medicine, or people who believe that childhood vaccinations cause autism—all of whom are as demonstrably mistaken as anyone can be—they understandably fight shy of revealing just how riddled with error and misleading information the everyday business of science actually is. When you paint yourself as a defender of the truth, it helps to keep quiet about how often you are wrong.

That fact partly explains why some influential climate scientists today, and the UN’s Intergovernmental Panel on Climate Change, are having a hard time. Wary of yielding any ground to those who think that global warming is some sort of hoax, they have sometimes been mightily unwilling to be open about exaggerations, mistakes and confusions in influential reports about climate change—such as the flawed “Hockey Stick” paper, published in Nature in 1998, which estimated global temperatures over the past 600 years, and has become one of the most cited publications on the topic. This defensiveness has backfired, and the credibility of climatologists has suffered.

At the end of her book “Science: A Four Thousand Year History” (2009), Patricia Fara of Cambridge University wrote that “there can be no cast-iron guarantee that the cutting-edge science of today will not represent the discredited alchemy of tomorrow”. This is surely an understatement. If the past is any guide—and what else could be?—plenty of today’s science will be discredited in future. There is no reason to think that today’s practitioners are uniquely immune to the misconceptions, hasty generalisations, fads and hubris that marked most of their predecessors. Although the best ideas of Copernicus, Galileo, Newton, Boyle, Darwin, Einstein and others have stood the test of time and taken their place in the permanent corpus of knowledge, error remains inherent in the enterprise of science. This is because interesting theories always go beyond the data that they seek to explain, and because science is made by people. Examples from recent decades of scientific consensus that turned out to be wrong range from the local to the largest possible scale: acid rain was not destroying forests in Germany in the 1980s, as it was said to have been, and the expansion of the universe has not been slowing down, as cosmologists used to think it was.
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