論理至上主義の陥穽：未来、そして歴史

さて、前回「神の可能性：人類、地球の存続にも関連して」を書いたわけだが、こういった内容は、それまでの内容が忘却されてあたかも論理至上主義のように認識される危険性をはらんでいる。しかし、以前未来で確実だと思っていることは実は願望に過ぎないという記事などからわかるように、私はむしろ論理至上主義を独善的かつ狭窄で危険な考え方だと見なしている。ところでこの論理至上主義への警鐘に関して、私が強く印象に残っている文章がある(もっとも、「専門家の精神性」と「彼らがいかに信用できない存在か」というのが主旨で、また権威主義への警鐘という側面もある)。以下、長くなるが掲載してみることにしよう。


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Don't believe the experts. Not only are they inaccurate a surprisingly large amount of the time, but they'll turn around and say they weren't wrong even when they were.

Philip Tetlock, a psychology professor, collected about 5,000 predictions from more than 200 experts over the past twelve years ― and then followed up to see how well they did.
　
In 1988, for example, he asked 38 leading authorities on the Soviet Union whether the Communist Party would still be in power in 1993. He also asked 34 American political experts in 1992 whether President Bush would be re-elected. And then he turned the spotlight on the specialists themselves, asking them how confident they were about their predictions.
　
So how did the experts do?
Not well, Tetlock found. Whenever a prediction could be tested for accuracy, barely half of the experts correctly predicted the events that occurred and only one in four showed "a substantial willingness to admit their error," Tetlock says. Almost half the experts thought that the Soviet Communist Party would remain firmly in power in 1993, that Canada would split apart by 1997, that South Africa would become a fascist state by 1994 and that the Gulf crisis would be resolved peacefully.

Confidence is no sign of accuracy, Tetlock found. Just the opposite: Those who said they were very sure of their predictions were right only 45 percent of the time-suggesting they would have been better off tossing a coin.

"More surprisingly, experts who were wrong were almost as likely as those who were right to believe their reading of the political situation had been basically correct," Tetlock says. Many top experts on the Soviet Union who had failed to predict the collapse of that nation told Tetlock later that they were "almost right."

Many who predicted a peaceful solution to the 1991 Gulf crisis said they had been fooled by the degree to which Saddam Hussein's behavior appeared to lack logic. "How can anyone know how his mind works?" one complained when asked to explain his own mistaken prediction.
　
Why are the experts wrong so often ― and why do they cling to their mistakes? "Most thought they knew more than they did" Tetlock found ― and then, out of stubborn pride, they were willing to argue illogically in defense of their predictions.
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人が論理で「計りきれない」ように、未来も、そして歴史も論理で「計りきる」ことなどできない。なぜなら、歴史を動かしているのがまさに論理で「計りきれない」人間だからである。

しかしこれに対し、ある人はこう言うだろう。「それでも、未来を見ていかなければ生きていくことすらままならない。だから私たちには予測という行為が必要不可欠なのだ」と。そう、実はそれこそが答えなのだ。要するに、論理などを用いて未来を、歴史を読んでいく際、「それでも、」という(限界を認識した)戒めを常に忘れないことが肝要なのだと言える(これを当たり前のことと思うなら、将来自分が自殺する可能性があることを[恐れるのではなく]認めることができるはずだ)。そしてこのような考えを持つが故に、私は決して論理至上主義を受け入れないのである。

未来や人間などの不確実性をはっきりと認識することは必要不可欠である。しかしそこから、「結局何も判らないのだ」と結論するならただの思考停止にすぎない。それが「結果ではなく前提」なのを認識して予測などを行っていくことが重要なのだと言える。