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Wednesday, June 20, 2007

how to decide

So I was arguing with Ed about CO2 and global warming.

When he flew back from Brussels not long ago, he sat beside some international science type who told him there is a near-absolute consensus that CO2 is causing global warming, and "the only interesting question" is what to do about it. The economists are figuring it out.

Ed reported this to me as settled truth. (Settled enough.)

Naturally I took it amiss.

I don't happen to have the first clue whether CO2 is causing global warming. Normally I assume CO2 is causing global warming because of the aforementioned near-absolute consensus.

However, if you made me bet money on CO2 being the cause of global warming, I wouldn't bet the ranch.

The reason I wouldn't bet the ranch is the aforementioned near-absolute consensus. My rule: in cases where everyone believes X, and where, more importantly, everyone fervently believes X, it's best to take a step back.

I don't know why I think this, exactly. Emotion per se isn't the problem. I believe, with Damasio & c., that emotion and reason are allied.

If you want to know why I have this decision rule or what role other people's emotions plays in it, you'll have to ask my cognitive unconscious. All I can say is that when emotion has led to dissenters being called "deniers" and the like, I assume we've left Damasioland.

Ed took that amiss.

I kept trying to say, "It's a writer thing," (which it is, for me at least) but that got me nowhere until I invoked Bayesian reasoning. Citing Bayes sounded good and it worked: "worked" meaning Ed decided to stop seeing my position as "they're in it for the (grant) money" and to start seeing my position as the logical result of a nonfiction writer applying a semi-conscious Bayesian heuristic to the problem.

So this morning I picked up Daniel Willingham's collection of classic articles in cognitive science, and found this: The benefit of additional opinions by Ilan Yaniv.

Lots of fun, and directly apropos:

  • in a study of inflation forecasts, the aggregate prediction was "more accurate than most ...individual forecasts, though not as good as the best ones. The best forecasts, however, could not be identified before the true value became known."
  • you only need 3 to 6 extra opinions to gain the full value of aggregated opinions
  • Condorcet's jury theorem, when applied to "categorical, binary judgments," is the exception that proves the rule - with binary judgments, the more experts the better
  • experts whose opinions you seek need to be independent to give you the benefit of opinion aggregation [score one for me]
  • otoh, "gains of appreciable size can be observed even when there are low or moderate positive correlations between the judgments of the experts." [one for Ed]
  • people are biased in favor of their own opinions (roughly: 70% favoring own opinion, 30% favoring advisor's opinion)
  • people are biased against dissenters [no kidding]
  • being biased against dissenters makes sense when there is a range of opinion on a subject ("fat tails")
  • I assume, though Yaniv does not say so, that the opposite is true: being biased against dissenters does not make sense when there is a near-absolute consensus

Which would mean that my "writer's rule" is a good one. In cases of near-absolute consensus buttressed by high emotion it's best to take a step back.

Naturally I apply this principle to constructivism (though not to instructivism - no, never!)

Joking aside, my Bayesian rating scale tells me that when a Stanford University School of Education professor publicly - and sympathetically - characterizes constructivism as a ruling ideology, I have just been told everything I need to know about whether constructivism is a correct model of the world.

...........................


I have to learn grammar.

I have no idea whether "Joking aside, my Bayesian rating scale..." is or is not grammatical.

Have I just said that my Bayesian rating scale has set joking aside?

I don't know.

I'm going to have to learn how to diagram a sentence, too.


Ilan Yaniv homepage

18 comments:

  1. Since I'm in the midst of working on a regulation at EPA that's come about because the President recently requested such, proposing a goal of 35 billion gallons of ethanol in gasoline by 2017 and which somehow provides for "Greenhouse Gas Reductions"

    This goes to the point of whether CO2 is the cause of global warming. From the Washington DC perspective, it doesn't matter whether it does or doesn't. In politics, perception is reality. The issue of climate change has reached the point that if you decide to debate whether climate change is real, or whether CO2 is the cause, you will lose political ground. And no one wants that. So now everyone has climbed aboard the climate change train.

    Just like in education: Process is more important than substance.

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  2. Note to Catherine: My first sentence above is a fragment, in case you were wondering.

    I really did intend to finish it, but forgot what point I was trying to make. Something Warriner's doesn't warn you about.

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  3. Something Warriner's doesn't warn you about.

    lol!

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  4. From the Washington DC perspective, it doesn't matter whether it does or doesn't. In politics, perception is reality. The issue of climate change has reached the point that if you decide to debate whether climate change is real, or whether CO2 is the cause, you will lose political ground. And no one wants that. So now everyone has climbed aboard the climate change train.

    I'm going to make you-know-who read this.

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  5. Global warming is a sham.

    At this point, it has become too political to even say "there's a consensus". There's only a consensus among people that feel it is an important enough topic to study which selects heavily for people that think that humans cause global warming and we need to do something about it. But, even among those people there are a lot of things that there is a consensus on.

    True -- the greenhouse effect and that CO2 is a greenhouse gas there is a consensus on. Though those that are imminently concerned about global warming mostly think that man has very likely contributed to the warming of the globe since the 1970s, there are still some significant hold outs that blame solar activity, for instance. Furthermore, there is a near consensus, also, that despite Al Gore's claims to the contrary, the globe is not warming very fast at all. Greenland, for instance, is not going to melt any time in even a hundred years. And, there is a near universal consensus on *that*, as well, and by scientists already concerned about global warming.

    Basically, all the world catastrophe predictions that have been made over the years aren't even going to remotely happen now with a decade or more of hidsight. The predictions keep having to be revised down as time goes by. And, I think that, more than anything, tells a nonscientist all they need to know. It's just a big exaggerated hoax. It's not even clear that the kind of wamring that *is* likely to occur is even a bad thing or how bad a thing it would be if a detremental amount of warming occurred.

    Just to add some facts to what I am saying, here are some from one of the critics of global warming:

    http://www.cato.org/pub_display.php?pub_id=8285

    "Greenland's total ice volume is 680,000 cubic miles, and it is losing four ten–thousandths of its ice per year. Do the math. That works out to 0.4 percent of its total mass per century."

    "The period from 1915 through 1965 — an entire half–century — was about two degrees warmer than it is today."

    http://www.cato.org/pub_display.php?pub_id=7502

    The warming path of the planet falls at the lowest end of today's U.N. projections. In aggregate, our computer models tell us that once warming is established, it tends to take place at a constant, not an increasing, rate. Reassuringly, the rate has been remarkably constant, at 0.324 degrees F per decade, since warming began around 1975. The notion that we must do "something in 10 years," repeated by a small but vocal band of extremists, enjoys virtually no support in the truly peer reviewed scientific literature.

    [So, that is like 3 or 4 degrees in 100 years. Consider that in 100 years we have seen the rise of the automobile, computers, nuclear power, space exploration. 100 years ago we were still predominantly riding around on horse powered vehicles. Do we really think that 100 years from now, the world is going to be just like it is today? We won't even make it to 100 years before our world has radically changed and a new issue for everyone to whine about comes along. But, I'm sure that they will say "See how all those extensive measures saved us from that global wamring scare," since there certainly won't be any global catastrophe.]

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  6. Uh, I cannot comment at this time. Where are the drinks?

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  7. ["Greenland's total ice volume is 680,000 cubic miles, and it is losing four ten–thousandths of its ice per year. Do the math. That works out to 0.4 percent of its total mass per century."]

    Hmmm. Doing the math gives me 4/10,000 x 100 = 4/100 or 4 %.

    Where am I going wrong? Maybe the 4/10,000 should apply to the new base each year (to what's left over).

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  8. Uh, I cannot comment at this time. Where are the drinks?

    hoo boy

    me, too

    I just took the "how tired are you" test and found out I am apparently NOT sleep deprived

    so I guess I probably have a fatal disease

    a fatal disease requiring a life-extending glass of red wine

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  9. One of the very smartest people I know told me the other day, "We only have 5 years."

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  10. I happened to be in a daze at the time (had yet to pick up my first bottle of Synthroid), and that didn't help.

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  11. I assume she meant 5 years UNTIL IT'S TOO LATE

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  12. One of the very smartest people I know told me the other day, "We only have 5 years."

    And that is where the skeptic alarm in me goes off.

    In my non-scientific opinion global warming is a complex phenomenon where what we don't know far outweighs what we do know.

    So I'm not too eager to make vast fundamental changes to our economic and social systems based solely on what we know today about global warming and its causes.

    There is a legitimate scientific debate going on about global warming. But to me the political debate reminds me too much of other displays of public enthusiasm.

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  13. In the meantime, I'm working on a regulation which has to be published in final form the last week in October 08: one week before the Presidential elections. You tell me what's going on.

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  14. We know that Mars is warming, since its polar caps are shrinking noticeably. We know that Pluto is warming.

    We know that CO2 is only a tiny proportion of the gases in the atmosphere that cause a greenhouse effect. (By far the biggest "offender" is water vapor.)

    We know that we are emerging from an anomalously cool period (the "Little Ice Age") that peaked in the 19th century.

    Clearly, human-generated CO2 is the cause of global warming.

    In other news:

    "Solar scientists predict that, by 2020, the sun will be starting into its weakest Schwabe solar cycle of the past two centuries, likely leading to unusually cool conditions on Earth. Beginning to plan for adaptation to such a cool period, one which may continue well beyond one 11-year cycle, as did the Little Ice Age, should be a priority for governments. It is global cooling, not warming, that is the major climate threat to the world."

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  15. Ben!

    Thanks so much for that book title!

    I love it!

    You've stated my EXACT feelings on the subject (feelings & thoughts), better than I did.

    Global warming seems massively complex to me, and as I've spent years of my life writing about science and raising money to fund research for preventions, treatments, & cures of autism, I have some confidence in my ability to perceive that a scientific question is complex.

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  16. Barry -

    What DOES that mean?

    the timing: what does the timing mean?

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  17. Doug

    Years ago I read quite a good article in the Atlantic Monthly arguing that the geological record shows that abrupt cooling has taken place in the past.

    "Abrupt" meaning very significant cooling of the atmosphere in a space of 10 to 15 years.

    I've lived in fear of abrupt cooling ever since.

    Naturally I'm quite willing to believe that global warming could cause ABRUPT GLOBAL COOLING.

    aaaaauuuuugggghhhhhh!!!!

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  18. Catherine:

    Dictating that a regulation (that purports to reduce greenhouse gas emissions from autos) be out one week before the presidential elections provides some indication that the rule may be something the administration can point to that they did with respect to global climate change.

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