It is time to stop quivering in our boots in pointless fear of the future and just roll up our sleeves and build it.
- Ray Pierrehumbert

Friday, March 30, 2007

About the "consensus" thing

Very interesting article here making some of the same points I just made.

However, I think it misunderstands the nature of the discomfort with the idea of "consensus" though. I think the idea of scientific consensus is so important and central to the way we manage our common interests in a modern democracy that it must be defended. What's more, I think it only needs defending because it is under attack.

We do come off as arrogant. I'm doing some thinking as to why. It surely isn't because of what we do right, though. Imagine equally two great musicians, one arrogant, one not. What is the difference between them? Does the modest one not play beautiful music for fear of making hopeless piano-pounders like myself feel embarassed?

What we do as scientists is discover truth. We can't be hiding that under a bushel barrel. You should fire all of us if claiming that we know how to discover knowledge is arrogance.

Consensus needs defending because "consensus" is one of the perfectly valid aspects of the scientific culture that is under attack. It is a delicate matter to defend it, because of all the various traps being set. However, this isn't a point we can afford to concede.

While letting generations go by without acknowledging how carbon emisssions impact the planet and making some steps to change would be a travesty, it is hard to say that throwing science away altogether wouldn't be worse. This isn't bathwater we are throwing away, but let's at least keep an eye on the baby, shall we?


David Duff said...

Michael, well done, it would have taken me a week to work out how to do it!

Idling in a book shop the other day I picked up a slim volume entitled "Kuhn vs. Popper" by Steve Fuller (I suspect this is only available in the UK but the mighty Amazon organisation might be able to supply). I had never heard of Kuhn but Popper was, and still is, something of a hero to me. To be honest I am having difficulty understanding all of it because Fuller, like so many other philosophers, tends to write books for other philosophers and thus indulges himself in their jargon. However, from time to time the mist clears and I see (or think I see) what he is driving at.

It seems that Kuhn was the instigator of this notion of 'scientific concensus', a state that was very much opposed by Popper. Kuhn's idea, apparently, was that science advances by means of a paradigm that holds, as it were, an umbrella over the heads of the "normal" scientists for very long periods of time, allowing them to beaver away at the minutae of science until enough puzzles build up to require a paradigm shift. During this period of stasis it is essential that the scientific community maintains a consensus.

Popper, of course, thought differently, believing that all scientific propositions should be constantly tested in an attempt to falsify them, not least because in Popper's opinion, *all* scientific propositions are falsifiable by definition.

Personally, I am a Popper-man but I wondered what your thoughts were and what justification you can offer for this current (last 60-years) and increasing desire for 'science man to speak with one tongue'! The implications for the AGW debate, of course, are obvious.

Michael Tobis said...

Hmm; it's interesting that Kuhn seems to keep coming up. (See also John Fernbach's comment on the globalchange list.

I am interested in Kuhn and Popper and the philosophy of science in general. I don't mean to put it down, but it isn't really relevant to most science. Outside of cosmology and physics, we aren't search for The Truth; we are searching for useful generalizations. I would cliaim that physics is not a good model for science as it is practiced precisely because it is about asking Big Questions; thus the Big Answers might amount to paradigm shifts in the Kuhnian sense.

A question like "is the contemporary buildup of CO2 anthropogenic?" is not, in that sense, a Big Question, though it is certainly an important one. It's not Big in that its answer will not affect the way scientists think about science. We will still be talking about sources and sinks, measurements and proxies, etc. in the unlikely event that this particular consensus is overturned.

It's also just about unimaginable that it is incorrect. That doesn't constitute evidence of the strawman claim that "global warming scientists claim that the global warming theory is settled" because there is no such thing, within science, as "global warming theory". There are a number of disciplines that constitute "climate science". Here we are dealing with a settled question in geochemistry.

It is a crucial component in the argument that an emissions policy is needed (which is pretty much what the opposition means by "global warming theory"), but it's craziness to be discussing it. Nevertheless people still bring it up; it's the most extreme example and they should probably drop it, but it brings the polemics nicely into focus.

When someone raises this matter they are trying to trap us in a bind. If we engage the issue with evidence, we give the question credibility. If we dismiss it we provide evidence of our arrogance.

No amount of non-reality-based thinking will change the fact that the recent accumulation of CO2 is caused by human activity. I doubt that any reasonably informed follower of Kuhn or Popper, or any serious philosopher of science has anything to add to this.

Science doesn't need to "speak with one voice" as you say, and it doesn't always do so. On the other hand, it sometimes does so, and that is because facts about reality are discovered through the scientific process.

Does CO2 accumulate in the atmosphere because of human activity? Science has a consensus on this matter, epistemology be damned.

David Duff said...

Aha! This should be interesting - little David Duff going up against a Goliath of Science! Unhappily, and not believing in fairy stories, I suspect the outcome of this confrontation will be a crushing off the upstart. Never mind, it was an American admiral, I think, who said, "Full speed ahead and damn the torpedoes"!

In reference to the philosophy of science you wrote, "I don't mean to put it down, but it isn't really relevant to most science." I would beg to differ. My belief is that the truly 'Big Questions' (as you put it) are philosophical, not scientific. What science does, it seems to me, is provide glimpses into the hitherto unknown which allows philosophy in general to inch forward towards some 'Big Answers'. Thus, that branch that deals with the philosophy of science is crucial because it provides a setting, an ambience, if you like, in which science can gauge itself. For example, any scientist who decides between Kuhn and Popper must have a hugely different conception of their place in the search for knowledge. Being unaware of this enormous gulf in scientific society until I read that book, and assuming, naively, that most scientists operated on the Popperian notion that *all* scientific propositions are falsifiable, I could not understand the closing of ranks amongst scientific AGW advocates. Now I do and I must say in all honesty, I don't like it!

Of course, both you and I live in the real world, not some idealistic university cloister in which matters of great moment can be discussed in a detached, scholarly manner - not that I qualify as any sort of scholar! Not the least of the problems of climate scientists (I use that as a generalisation covering all the specialities) is that, unlike the particle physicists chasing neutrons, no one outside the accelerator sites gives a damn! But with climate science, the politicians care very much indeed. It's not the fault of the scientists concerned (at least not all of them, but human nature being what it is ...) but they do need to be extraordinarily careful about how their theoretical 'gropings' are used by those self-serving rascals. And it's no use moaning that you, the scientists, are not political. A particle accelerator probably costs me, personally, about 1p. p. year, but some of the propositions rushed forward by politicians with whom I would not trust my cat, are likely to cost me serious money to say nothing of serious threats to my liberty (already there is talk of "personal carbon passports", a licience for every little commissar in the world to strut his stuff!)

Thus, when you write "we aren't search[ing] for The Truth; we are searching for useful generalizations" I must tell you, very honestly, that simply will not do! Also, I find myself confused when scientists like you proclaim that "No amount of non-reality-based thinking will change the fact that the recent accumulation of CO2 is caused by human activity" when I can point you in the direction of well-qualified, even emminent, scientists who do *not* agree. Granted, they might be outnumbered ten to one, but to begin with so was Lavoisier when he suggested that phlogiston did not exist; and so was Alexandre Yersin when he 'discovered' that rats caused bubonic plague and then his 'discovery' became the orthodoxy until recently when, a century later, it is subjected to attack!

And so on, and so on ... that is the history of science but you can understand why an outside layman, like me, nervously holding his wallet and never leaving the house without his passport takes a very sceptical view of *anyone* in *any* branch of science who says that such-and-such is a done deal!

Michael Tobis said...

I find myself confused when scientists like you proclaim that "No amount of non-reality-based thinking will change the fact that the recent accumulation of CO2 is caused by human activity" when I can point you in the direction of well-qualified, even emminent, scientists who do *not* agree. Granted, they might be outnumbered ten to one, but to begin with so was Lavoisier etc.

I am willing to bet that you cannot find a single scientist who disagrees or even questions the particular assertion in any published peer reviewed article published since 1970.

At best, you are not reading carefully or you don't know anything about the science of the matter at hand.

I didn't say everything in the IPCC report was unanimous. I said that the fact that accumulation of CO2 is anthropogenic is unambiguous. I don't think this is a matter of philsophy any more than is the question of the heliocentric model of the solar system.

You can split hairs and build castles in the sky all you like but for practical purposes that the earth goes round the sun is a fact, and it was established as a fact through scientific consensus long before Popper or Kuhn were born.

I also don't think a working astronomer has to vote between the Popper and Kuhn, as if they constituted an exhaustive set of possible philosophies of science, before proceeding with a study of orbital dynamics.

I agree that there is a sensible test about falsifiability that is important at the fringes of science. As far as I know nothing asserted or debated in climate science falls into the Popperian category of non-falsifiable, so your talk is to me very much yet another red herring.

EliRabett said...

Kuhn came after Popper, and was a response to Popper's ideas. IMHO he pretty much demolished Popper, who, again, IMHO thought about science in a very junior high school way.

Michael Tobis said...

NIH has a definition of consensus
and a consensus process, apparently.