So I was having a mini-debate with Say Uncle about global warming (in response to this excellent Krugman piece on the topic), and Uncle made an argument that I frankly thought was idiotic. First, though, some background. In response to the piece, Uncly Wuncly complained that Krugman had engaged in “quasi-reasoned yammering about how a majority = right” (I had called his initial snark “quasi-clever”). I responded:
[T]here’s a pretty big difference between a majority of people and an overwhelming majority of qualified experts who have actually studied the subject matter in question. Is it possible that they’re wrong, and the minority is right? Sure it is. But it’s not bloody likely, and it’s certainly not a good reason to try to discredit the people who say “maybe we ought to listen to them.”
To which he responded, “see appeal to authority, logical fallacy.”
So according to him, there’s no significant difference between “X must be true because Dr. Foo [one guy] of the X Institute says so,” and, “Y is almost certainly true because the overwhelming majority of credible experts who have studied the subject have come to that conclusion.” Now, as I said above, it’s still possible that the overwhelming majority of credible experts is wrong. But an argument from authority, it ain’t.
But I was having a hard time figuring out explaining just WHY his stance struck me as so preposterous. And I think I have an example to illustrate why.
Suppose you’re a smoker. Now suppose you’re having respiratory and cardiac problems, and your doctor tells you that smoking is exacerbating and probably causing your problems, and you need to quit smoking. Now, you love smoking, so of course you seek out a second opinion. And a third. And a fourth. And so on, until you’ve seen twenty doctors about the problem. Of the twenty, nineteen agree that smoking is Very, Very Bad for your particular symptoms, and that you need to quit. The twentieth says smoking is fine, no need to change anything. Now suppose further that the nineteen who agree are all cardiologists and pulmonologists, with perhaps one or two general practitioners thrown in. The guy who says the other nineteen are wrong, that smoking is no problem is a dermatologist. And to boot, the dermatologist works for R.J. Reynolds.
Given this scenario, what do you do? Do you quit smoking, and go with the clear majority of expert opinion? Or do you continue smoking, insist that the dermatologist must be right, and that there’s no reason to believe that the nineteen cardiologists and pulmonologists are right, and that anyone who trusts the opinion to the nineteen is making a fallacious appeal to authority?
If you’re a member of that second group, congratulations! You’re SayUncle!
NOTE: The primary flaw in my analogy, when comparing it to anthropogenic global warming science, is that the ratio in AGW science is tilted a lot more heavily than 19 to 1. By allowing 5% dissent, I’ve actually
grossly exaggerated how much is really out there in the case of AGW. [See below for correction.]
Footnote to the Preceding Note: In our mini-debate, Uncle also claimed that “the ‘overwhelming majority’ tends to refer to scientists who are not climatologists.” Unless I misunderstand his complaint, he’s got this exactly backward. See, for example this January 2009 survey of Earth Scientists, which found that:
Results show that overall, 90% of participants answered “risen” to question 1 and 82% answered yes to question 2. In general, as the level of active research and specialization in climate science increases, so does agreement with the two primary questions (Figure 1). In our survey, the most specialized and knowledgeable respondents (with regard to climate change) are those who listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individuals in total). Of these specialists, 96.2% (76 of 79) answered “risen” to question 1 and 97.4% (75 of 77) answered yes to question 2.
For reference, the two questions they asked:
- When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
- Do you think human activity is a significant contributing factor in changing mean global temperatures?
Bottom line: the more one actively studies the Earth’s climate and client science, the more likely one is to conclude that human activity is a significant contributing factor. Contrary to Uncly-Wuncly‘s claim, climatologists are substantially more likely that scientists at large to make that conclusion. Though I will note that 1 out of 20 was actually less exaggerated than I would have thought.
UPDATE 2009-12-09 21:44 CST: “Climategate” is, of course, getting a lot of press here. Here’s New Scientist’s take on the matter. The NRDC also weighs in. And, of course, RealClimate offers one-stop shopping. As does SwiftHack (presumably, the name alludes to the anti-Kerry hit group Swift Boat Veterans for
Misrepresenting the Truth).