I’m observing a remarkable constellation of very high information-density items popping up in the news. My favorite, just on aggregate looniness grounds, is that (i) Grover Norquist has arranged for the (ii) CPAC to be infiltrated and subverted by the (iii) Muslim Brotherhood. Then there’s the astonishing 1998 finding that vaccinations cause autism. A Cornell psychologist has demonstrated precognition. In the “news you can really use” department, why we don’t need to worry about air fares this summer. And on the other side, we learn that the strongest correlate of rejection of the avalanche of consistent, varied, tested, evidence of anthropogenic global warming is personal political preference.
The information in a signal, I hasten to point out, is the negative logarithm of its prior probability of reception, and that probability is a property of whoever is receiving it. This can get complicated; it’s not surprising to me that Frank Gaffney at any moment will say something totally batsh.t, but “the CPAC is lousy with Muslim terrorists” was probably quite surprising to the ACU’s people. The information in a signal is not at all the same as the truth of the signal’s content, though; that a signal “A is B” has very low probability for receiver X is equivalent to “X believes A is not B”, so there’s the issue of base rates. Most people are Bayesians, integrate new information with what they already know, and when they hear hoofbeats, think horses, not zebras. And not, in Arthurian England, coconuts; the discussion of these in the movie raises the further issue of how fairly patent evidence should be integrated with the complete absence of any plausible theory to explain it, relevant to precognition and all the other psychofakery out from under which James Randi keeps pulling the rug. Global warming, early on, was a coconut among the gold standard, cold fusion and lots of zebras and unicorns, but now it’s not; it doesn’t do to ignore unlikely signals, any more than it’s wise to embrace something just because it has a high wow index.
Integrated into what? It would appear, belief. But it’s not so clear what this is. Statements of belief are an indicator, but no more, because talk is cheap and anyway the best predictor of what we say is what we want to be heard saying, especially “hear ourselves saying”. Irretrievable commitment of resources is a better one; being late for a meeting because you waited for a traffic light to cross a busy street is pretty good evidence of what you believe about the physics of vehicle-pedestrian impact. But not perfect: global warming deniers almost certainly include some folks who would rather make more money selling fossil fuels in the near term than leave future generations a habitable planet; Andrew Wakefield seems to have simply sold the children of strangers for a big fat bribe.
Belief is very social. It’s not just that the people you hang out with greatly bias your sampling of evidence in their conversation, but that they reinforce this or that view of your own worth. I wouldn’t be surprised if it’s now so comfortable for Wakefield to think of himself as a fighter for truth and children’s health, basking in the adulation of Jenny McCarthy and her friends, that he really believes the nonsense he unleashed. (He should still be in jail.) And of course reputation and self-regard are resources, so the more of them you’ve bet on filling a 10-Q-K-A straight with three jacks showing in other players’ face cards, the harder it is to fold.
There’s no escape from engaging with surprising propositions. Any one of them is probably wrong, but you have a lot to gain by acting on the ones that aren’t. Base rates and priors (not hopes and ego!) are relevant and useful; it should have taken a lot more than twelve kids and one paper to derail all the other evidence of the net salutary effects of vaccination. Follow the money never hurts, cui bono? Finally, there’s a utility test, as in, “so what?” As an engineer I was trained to respect empirical equations, like the ones we still use for turbulent flow in pipes even while we hope for something better, because they are useful and the more elegant theoretical model will trash your plumbing. Conversely, an amazing proposition with no utility is probably just wrong: they took the thimerosal out of the vaccines and autism rates didn’t change. A good diagnostic of pseudoscience like pyramids and spoon-bending is the enduring triviality of the purposes to which it can be put; anyone who can really move objects at a distance by will would be disarming bombs, not bending spoons; who wants his spoons bent? If you can see the future, you will be cleaning up on Wall Street, not predicting that a dirty picture will pop up on a computer screen. Even if a pyramid over my sandwich makes it spoil more slowly, why is that better than the refrigerator (not to mention, how does the pyramid know not to do its other miracle, accelerating decay, which is promised if I put it over my compost pile)?
Evidence based reasoning is hard to find. I've had a number of people tell me recent animal death events (Arkansas, Sweden, Chesapeake Bay to be related because they were reported in the same week. The response to why they have to be related is hand waving that the "odds are against" multiple unrelated events.
I'm genuinely curious how often deaths of 100 or more animals are reported in a 24 hour period in a small geographic area. I suspect it is a lot higher than intuition would lead one to believe (say 200 animals found dead in a one hectare area in a 24 hour period is reported somewhere in the world every week). The end times folks are all hysterical about the recent reporting.
I'm not so sure global warming was ever in the implausible category. It's been known since the first understanding of thermal radiation that the Earth is substantially hotter than a simple black-body steady-state with the Sun would imply. Furthermore the role of water, CO2 etc in maintaining that difference via infrared absorption has been well understood. Arrhenius' 1896-1906 work predicting the CO2-driven increase was never challenged as crackpot. All that's really happened since is that we've started emitting CO2 much faster, and the new data and modeling have helped improve the still-large error bars on the feedback coefficient.
BTW, slightly OT, Keith H's aside that it might be too late to "stop" global warming was irresponsible babble, not based in science. None of the models show the hysteretic bistable behavior suggested in that comment, except possibly (not at all likely yet) for local North Atlantic circulation. We're very much in the what you get is proportional to what you put in (with a long time delay) stage. Every increment counts.
Getting people to really understand probability is difficult under the best of circumstances. Take the classic Tversky question about the feminist bank teller: even people who really understand probability can rebel about it. When what we know mathematically conflicts with what we know socially, most people opt for what they know socially.
I despair over the idea of trying to get mathematically naive people to understand the principles and ideas of statistical information. Until someone really understands probability, teaching them about statistical information is a chump's game.
The fact is, low probability events happen all the time. Two people just won the Multi-State Lottery jackpot — the statistical question is not, "How surprising is this?," but rather, "How repeatable is this?" The core principles of statistics are randomization and replication. The idea behind replication is to determine how repeatable a process is. Winning a lottery is a very low probability (and hence surprising) event. What it isn't, is a repeatable thing. We know that, because the experiment is run constantly via the quick-pick mechanisms.
"We’re very much in the what you get is proportional to what you put in (with a long time delay) stage. Every increment counts."
That's part of what gets me eye rolling. I keep hearing about the "basic physics", but everything I know about the basic physics says that the greenhouse effect must be subject to saturation, declining returns. Instead we get these simple minded linear extrapolations.
Brett- From Arrhenius on, the CO2 forcing term has been treated as logarithmic in [CO2]. In modern models essentially the same functional form emerge from a more detailed calculation. So yes, for large excursions,e.g. doubling, that's not quite linear. It's not close to saturating, and (the point here) is that it has no hysteretic instability, but remains an analytic function of the input. Nit picking!
BTW, re an old post, I suggest you might read an elementary thermodynamics text re your idea about desalinization using big tubes and semi-permeable membranes. Great idea, other than being a perpetual motion machine.
I refer you to the inimitable XKCD:
http://xkcd.com/808/
"BTW, re an old post, I suggest you might read an elementary thermodynamics text re your idea about desalinization using big tubes and semi-permeable membranes. Great idea, other than being a perpetual motion machine."
It is, in fact, not a perpetual motion machine. The energy needed to separate the water from the salt is supplied by dropping the salt to the bottom of the ocean, (Think of the water as just a conveyor carrying salt down, and coming up empty.) and it would eventually stop working when the bottom of the ocean became more saline, if there were not natural processes stirring the ocean up. I didn't dream it up, I attended a presentation on it at a scientific conference.
The main drawback is that it requires a very low maintainance membrane, as the membrane is located, duh, at the bottom of the ocean.
Brett- Reverse osmosis purification of seawater requires about 24 bar minimum pressure in principle. (More in practice.) Seawater is about 2.5% more dense than pure water. So even for 5 km deep columns, the pressure difference between the bottoms of the seawater and pure water columns would be about 13 bar. You'd be increasing free energy, not decreasing it. Check my math, this could be mistaken. On the other hand, so could the anonymous person you heard at a scientific meeting.
Another way of seeing this is that in equilibrium a deep column of seawater would be saltier at the bottom than the top, but the top would not be close to "desalinated".