This inescapable fact, that the conditioning evidence is only assumed and is therefore subjectively defined, is responsible for much acrimony about accuracy. Thus the reason we attempt to eliminate wiggle room and that we insist on clear lines in advance is obvious. We don’t want some slicker coming along and claiming to be better than he is or right when he was wrong. Just in case it isn’t obvious, let’s pick a non-controversial topic to illustrate the intolerable nature of fuzziness.
At Fong’s Great Wall restaurant you open your fortune cookie which reads, “You will find happiness.” You pay the bill, head out to the car, and find a quarter on the seat. Does that make you happy? Next day, your learn that the project on which you were to work was canceled. Your workmate takes you out to lunch and foots the bill. Happy? Or perhaps you are a bureaucrat at the Environmental Protection Agency, stuck in a dour cubicle in some sub-basement, daily writing papers on newly discovered menaces and risks to our planet, papers which none but other bureaucrats will ever read. Then, the day after opening the fortune cookie, you learn your department has been cut from the budget and you will finally find freedom. Thus shall you find happiness?
It’s obvious why we should ignore prophecies from Chinese-American pastries: they are too absurd, too loose, too variable to be considered seriously. But how much more soberly should we consider the economist who says, “The Economy (stock market, company, etc.) will improve”, the sociologist who predicts, “Racism (disparity, inequality, etc.) will continue”, the journalist who writes, “The candidate I secretly support (but whom I hope nobody guesses I secretly support) will improve his election chances”, the military strategist who says, “Iran will make aggressive moves”, the environmentalist who says, “The climate will warm and then bad things will happen”, or the futurologist who says anything?
Each of these statements are so ridiculously watery that they fit any receptacle. They are intellectual tea leaves: anything can be read into them. They are all fortune-cookie predictions, except that fortune cookies are superior: at least with the fortune you get a cookie. These statements are free of calories, and they are harmful if swallowed. They are “predictions” that simultaneously obtain or fail, depending on how sympathetic one is to the person making the prediction and not how closely the predictions match empirical observations. These intolerably vague scenarios are one large reason scientists (and other folk) are more confident of themselves than they have a right to be.
In short: each of these are scenarios and not predictions. A scenario has all the trappings of a prediction. It looks like one. It smells like one. It can be used like one. But when you cut it open and examine its viscera, you discover it is a different creature altogether. Scenarios are used by the nefarious to cheat, aggrandize, and bamboozle. They are issued in lieu of predictions by the ignorant. The saddest scenarios are those that not only fool the recipient but also the issuer.
Scenarios are predictions lite. They have conditions, just like predictions do, but one is not meant to look too closely at them. They are meant to be vague, or rather blank, the interpretations to be filled in later. The fortune cookie was a scenario, as are most psychic and political predictions. The scenario’s conditions are infinitely malleable, allowing each individual to find comfort in them, if they are so predisposed.
Saying “the economy will improve” sure sounds like a prediction, doesn’t it? But it’s no different than when a palm reader says “I see difficulties ahead.” For what does “improve” mean? Can it be rigorously defined? What makes up the economy—what specifically? And when will this “economy” improve: tomorrow? next week? next year? Given the heterogeneity of things economic, and the imprecision of dates, it is with a probability approaching certainty that eventually some quantitative measure will show improvement. This new, but unstated proviso, makes it almost certain that the prediction will be a hit.
But the heterogeneity also makes it all but certain that other economic quantitative measure will show a deterioration, which (if taken as a proviso) makes it almost certain the the prediction will be a miss.
As we’ve stressed here before, it is well to be clear that “almost certain” does not mean “certain”. Nor does “practically false” mean “false”. Saying that an event is “practically false” is logically equivalent to saying she is “practically a virgin.”
This took more time than originally planned. The IPCC scenarios are next. Promise!