Over at Rationally Speaking, Massimo Pigliucci has a useful post on James Randi's recent "sceptical" comments on anthropogenic global warming, which he followed up on in a supposedly clarificatory note a couple of days later.
Before I go on, I should say that I have long admired Randi's work in debunking pseudo-science and paranormal claims, such as those of Uri Geller. If there's anyone I'd like to give a free pass to ... well, it's hard to think of a better candidate. I'm delighted to have an essay by him in 50 Voices of Disbelief: Why We Are Atheists, and I'm reluctant to kick his head over this one issue, however important it is.
That said, it's disappointing to see Randi taking the approach he has to what is, after all, a very important issue where confusion reigns. As Pigliucci puts it: "these waters have been quite muddied already by big corporations who have been actively engaged in public deception about this issue for years, so that public opinion and politicians are already confused enough, almost to the point of paralysis. I really think this was an uncharacteristically bad target for Randi to choose."
Randi's position seems to be that he does not doubt the scientific consensus that the Earth has warmed by about 0.7 degrees Celsius since about 1850. He considers the claim that this warming has been significantly (let's say half or more) the result of human activity to be "likely" or "probable". However, he thinks there is room for reasonable doubt, based on such considerations as the complexity of inputs to climate and on the fallibility of scientists, who can be driven by peer group pressure and other less-than-exemplary motivations. Putting his case as charitably as I can, he seems to assume that the science of AGM is at an early stage and that it is still reasonable to doubt its key finding of significant human contribution to global warming, even though the latter is likely to be vindicated over time.
Randi was initially taken in by the, ahem, somewhat misleading "Petition Project", which collects thousands of signatures from individuals who doubt or deny anthropogenic global warming. He apparently now accepts its dubious provenance and very low probative value. He concludes in his clarificatory remarks:
Again, the importance and the impact of this phenomenon is well beyond my grasp. I merely expressed my thoughts about the controversy, and I received a storm (no pun intended) of comments, many of which showed a lack of careful reading that led to unfair presumptions and interpretations. Will I do it again with other subjects? Without fail, I promise you. This is what human interaction is all about, what makes it important. I've shown that I can make observations on subjects barely within my understanding, while admitting my shortcomings, and provoke reactions that are interesting, constructive, and sometimes furious. That's okay. Language is a means of expressing one's thoughts and opinions without resorting to fisticuffs or worse. This encounter was bloodless, gentlemanly, and civilized.
Unfortunately, that remains problematic. Randi concedes that he is not at all expert (or even well-informed) in this field, but he still wishes to make an assessment that a key finding is merely "likely" or "probable" when that finding is now well-established science, with a strong consensus in the relevant peer-reviewed journals. It has gone far beyond the stage of "interesting conjecture" or even "best-candidate hypothesis".
That does not, of course, entail that the theory is as robust as, say, the heliocentric picture of the Solar System or the evolutionary account of the diversity of life forms (and their appearance of intricate design). These theories are now so well-established and successful, over such long periods, that it is almost unimaginable that their central claims could ever be overturned by future observations. For all intents and purposes, they are as certain as that I am Russell Blackford, typing these words on my desktop computer. AGM is not so well-established as that, but what are we to say, and how are we to act, when it is now the overwhelming consensus of experts in the field who have no vested interest in fudging the results?
I must emphasise that this is not a situation where dubious intuitions or interpretations are relied on to produce convenient "truths" that obtain their real psychological attraction from religious or ideological leanings, or from the idiosyncracies of people's experiences. It is hard science, based on physical evidence and accepted by experts who come from many cultural, ideological, and other backgrounds.
Obviously, research on alternative hypotheses should continue. However, those of us who are not at the cutting edge would be irrational if we did not at least accept a very high likelihood (no use trying to put a percentage on it) that the key scientific claims about anthropogenic global warming are true. Likewise, in the current state of knowledge, policy-makers would be irrational to proceed on any other basis. Perhaps Randi doesn't really disagree with this, but he has worded his two pieces in a way that suggests he might.
Part of the reason this seems to have gone wrong is the very term "scepticism" (or "skepticism" as my American friends spell it). As Pigliucci notes, this term means, in context "a science- or evidence-based approach to the examination of unusual claims, typically in the realms of the paranormal, astrology, alternative medicine and the like." It does not refer to some sort of Pyrrhonic philosophy that doubts all truth claims, based on radical epistemological arguments. Pigliucci concedes that, "More recently, skeptics have expanded their aim to include some controversial issues in science, under the reasonable position that science itself should not be exempt from critical analysis." However, he adds, I think quite properly, the following note of warning:
Fair enough, except that science already has a large number of professional critics: scientists themselves (remember the peer review system?), as well as philosophers and sociologists of science. Moreover, while critical analysis of claims of the paranormal does not really require professional scientific expertise (indeed, Randi’s own spectacular career shows that the pertinent expert is more often a magician, since wannabe paranormalists often employ trickery to fool the public), actual science criticism does.
This seems right. Like anyone else, James Randi is politically free to think and write what he wishes - or at least he should be. But an issue such as AGM is not one where his particular expertise is likely to be helpful, and he should realise this. Indeed, it appears that he does, given his various disclaimers about lacking the relevant intellectual background. He is no better placed than any other intelligent person with a general understanding of science to suggest the conclusion that the "A" in AGM is dubious science. His main reason is the complexity of the global climate system, but it's not as if the scientists concerned are unaware of this complexity or are making pronouncements in ignorance of it.
The whole thing episode goes wrong at the very beginning, when Randi writes as follows: "Though this subject is not one that directly concerns the JREF, I'm very frequently asked if I'll turn my skeptical eye to it. As a year-end fling, I'll give it a try." But why should people be asking him "frequently" to turn a "skeptical eye" on matters of well-established mainstream science? That is not what scepticism is, in the current context. Again, scientific scepticism is not Pyrrhonism.
Randi should not have been tempted. The role that he has carved out for himself does not involve casting doubt on mainstream scientific theory about which he is professedly largely ignorant. If anything, it would make more sense to turn his scientifically-based scepticism to anti-scientific claims that attempt to challenge the consensus ... without actually carrying out studies suitable for publication in the appropriate journals. Yes, he is entitled to have opinions on all sorts of things, but it is unhelpful when he expresses ill-informed ones that are not based on the best current science, but on general speculation about peer group pressure and the like.
Pigliucci sums up the position well, when he writes:
James Randi is a major player in the skeptic movement, and that kind of position comes with responsibilities, one of which is that he really ought not to just wonder aloud about his opinions unless he has put in the time to do serious background reading on the matter at hand. I remain respectfully disappointed.
I agree. What's more, Randi has now done unnecessary damage to his own reputation. His opinions will henceforth carry less weight with reality-based people, and the situation is not helped by his assurance that he will do something like this again in the future, with other subjects. I hope it won't happen that way; we need his contribution to our culture, but in a manner that reflects his real abilities. It's a loss to us all if he dilutes his contribution with pronouncements that merely make it difficult to know when he speaks with a degree of authority and when ... well, not so much.