Vad är skillnaden mellan vetenskapliga fakta och teori? Skillnaden kan vara hårfin och är alltid avgörande.
Klimatforskaren Judith Curry har publicerat en fin text om vetenskap, skriven av Mario Livio. Jag hoppas att denna text bidrar till än fler läsare av Currys välskrivna blogg och av boken Brilliant Blunders.
Science consists of facts and theories. Facts and theories are born in different ways and are judged by different standards. Facts are supposed to be true or false. They are discovered by observers or experimenters. A scientist who claims to have discovered a fact that turns out to be wrong is judged harshly. One wrong fact is enough to ruin a career.
Theories have an entirely different status. They are free creations of the human mind, intended to describe our understanding of nature. Since our understanding is incomplete, theories are provisional. Theories are tools of understanding, and a tool does not need to be precisely true in order to be useful. Theories are supposed to be more-or-less true, with plenty of room for disagreement. A scientist who invents a theory that turns out to be wrong is judged leniently. Mistakes are tolerated, so long as the culprit is willing to correct them when nature proves them wrong.
Brilliant Blunders, by Mario Livio, is a lively account of five wrong theories proposed by five great scientists during the last two centuries. These examples give for nonexpert readers a good picture of the way science works. The inventor of a brilliant idea cannot tell whether it is right or wrong. Livio quotes the psychologist Daniel Kahneman describing how theories are born: “We can’t live in a state of perpetual doubt, so we make up the best story possible and we live as if the story were true.” A theory that began as a wild guess ends as a firm belief. Humans need beliefs in order to live, and great scientists are no exception. Great scientists produce right theories and wrong theories, and believe in them with equal conviction.
The essential point of Livio’s book is to show the passionate pursuit of wrong theories as a part of the normal development of science. Science is not concerned only with things that we understand. The most exciting and creative parts of science are concerned with things that we are still struggling to understand. Wrong theories are not an impediment to the progress of science. They are a central part of the struggle.
The five chief characters in Livio’s drama are Charles Darwin, William Thomson (Lord Kelvin), Linus Pauling, Fred Hoyle, and Albert Einstein. Each of them made major contributions to the understanding of nature, and each believed firmly in a theory that turned out to be wrong. Each of these examples shows in a different way how wrong ideas can be helpful or unhelpful to the search for truth. No matter whether wrong ideas are helpful or unhelpful, they are in any case unavoidable. Science is a risky enterprise, like other human enterprises such as business and politics and warfare and marriage. The more brilliant the enterprise, the greater the risks. Every scientific revolution requires a shift from one way of thinking to another. The pioneer who leads the shift has an imperfect grasp of the new way of thinking and cannot foresee its consequences. Wrong ideas and false trails are part of the landscape to be explored.
The chief difference betwen science and other human enterprises such as warfare and politics is that brilliant blunders in science are less costly. Hannibal’s brilliant crossing of the Alps to invade Italy from the north resulted in the ruin and total destruction of his homeland. Two thousand years later, the brilliant attack on Pearl Harbor cost the Japanese emperor his empire. Even the worst scientific blunders do not do so much damage.
In my own life as a scientist, there was one occasion when I felt that a deep secret of nature had been revealed to me. This was my personal brilliant blunder. As my mother taught me long ago, the key to enjoyment of any sport is to be a good loser.
In Livio’s list of brilliant blunderers, Darwin and Einstein were good losers, Kelvin and Pauling were not so good, and Hoyle was the worst. The greatest scientists are the best losers. That is one of the reasons why we love the game. As Einstein said, God is sophisticated but not malicious. Nature never loses, and she plays fair.