The devotees of "global warming" are at it again. These idiots – and I use the term according to its dictionary meaning: persons of intellect so severely degraded that they shouldn’t be allowed out of the house alone – are crowing and having innumerable ecstasies over this supposed success by a climate model:
Scott Adams, who’s a hell of a lot smarter than most folks would imagine a “professional cartoonist” to be, is probably holding his sides in by main force over this:
I will bet anyone $1 million dollars that I can come up with a climate forecast model that ignores C02 and still predicts the temperature 30 years from now to within half a degree. Does anyone want to take that bet?
Obviously there is a trick involved, so I won’t accept your bet for ethical reasons. But let’s see if you can figure out how I could win that bet every time.
I am 100% confident I can build a climate prediction model, using my current skill set, that will predict the measured temperature in 30 years to within half a degree.
Furthermore, you can pick whatever measurement type and place you want for the bet. My trick does not depend on doing anything clever with the measurement itself.
The trick – which is actually a demonstration of a core principle of science – is called survivorship bias:
Survivorship bias, or survival bias, is the logical error of concentrating on the people or things that "survived" some process and inadvertently overlooking those that did not because of their lack of visibility. This can lead to false conclusions in several different ways. The survivors may be actual people, as in a medical study, or could be companies or research subjects or applicants for a job, or anything that must make it past some selection process to be considered further.
Survivorship bias can lead to overly optimistic beliefs because failures are ignored, such as when companies that no longer exist are excluded from analyses of financial performance. It can also lead to the false belief that the successes in a group have some special property, rather than just coincidence (Correlation proves Causation). For example, if three of the five students with the best college grades went to the same high school, that can lead one to believe that the high school must offer an excellent education. This could be true, but the question cannot be answered without looking at the grades of all the other students from that high school, not just the ones who "survived" the top-five selection process.
Exactly. This sort of criterion for claiming knowledge is a classic logical fallacy. As Thomas Sowell wrote in The Vision of the Anointed, by using this sort of “logic,” one could “prove” that no one died in World War II, simply by interviewing only survivors.
Trust only – and always with reservations – the predictions of a man who’s successfully predicted not one but many outcomes, always before the occurrence of the event and always by using the same causal model. As I wrote in one of my better short stories:
"Are you a scientist in name only, Dr. Culloden, or in fact?"
The researcher stiffened. "What do you think, my unwilling guest?"
"I think you have evaded the question."
"I am a scientist." He hurled the words at the Dark Angel, a return of service of the glove Uriel had hurled into his face.
"What is the first rule of science?"
"Prediction is knowledge."
"How many counterexamples are required to disprove a theory?"
Culloden could see the end of the syllogism. "One."
"Then let us return whence you found me."
Prediction is knowledge. By corollary, if one makes N “predictions” (where N is “enough to cover all the possible outcomes”), each of which differs from the others by no more than the previously agreed-upon acceptable margin of error, and afterward suppresses mention of the N-1 that fell outside that margin, one is not practicing science or demonstrating knowledge, but playing a confidence game, a sort of probabilistic Three-Card Monte.
Even real, scrupulous scientists can fall afoul of survivorship bias. Sir Fred Hoyle knew that, too:
"It looks to me as if those perturbations of the rockets must have been deliberately engineered," began Weichart.
"Why do you say that, Dave?" asked Marlowe.
"Well, the probability of three cities being hit by a hundred-odd rockets moving at random is obviously very small. Therefore I conclude that the rockets were not perturbed at random. I think they must have been deliberately guided to give direct hits."
"There's something of an objection to that," argued McNeil. "If the rockets were deliberately guided, how is it that only three of 'em found their targets?"
"Maybe only three were guided, or maybe the guiding wasn't all that good. I wouldn't know."
There was a derisive laugh from Alexandrov.
"Bloody argument," he asserted.
"What d'you mean, 'bloody' argument?"
"Invent bloody argument, like this. Golfer hits ball. Ball lands on tuft of grass -- so. Probability ball landed on tuft very small, very very small. Million other tufts for ball to land on. Probability very small, very, very very small. So golfer did not hit ball, ball deliberately guided onto tuft. Is bloody argument, yes? Like Weichart's argument....Must say what damn target is before shoot, not after shoot. Put shirt on before, not after event."
Quite a few “investment gurus” have staked their reputations on having been right...once. Some of them are wearing orange jumpsuits and eating substandard meals today. Don’t stake your money on their supposed foresight.
Or on mine.