Let me tell you a story you may have heard before.
The Positivists held that if any claim was false -- any meaningful claim-- then there must be some observations that might be made that would prove, to anyone who understood the claim, that it was false.
Quine taught us that this is wrong. It's wrong because no claim is ever tested against observations singly. The relevance of any evidence to any hypothesis is always mediated by a host of ancillary assumptions. Our confidence in those assumptions and their relevance to the hypothesis in question always depends upon our background theory. This makes it possible for us to agree about what was observed but disagree about what it proves because we bring different theories to the observing.
This means that you and I might disagree about the truth of some claim, and yet there be no possible observation that could tell us who was right. Evidence that you took as falsifying the claim, I would explain away by rejecting your ancillary hypotheses or their relevance. You would reject that explanation, but your reasons for doing so would involve assumptions that I turn reject. And, of course, when I offer you evidence that you are wrong about those, you will have your own ways of explaining it away.
And so it might go, back and forth, forevermore. Not because either of us was irrational, or unreasonable and not because (as the positivists would have insisted) we mean different things by our words, but because observation is theory laden.
Note that it is consistent with all this that our competing theories might nevertheless be very good theories: each in their own way capable of predicting, explaining (and explaining away) everything that happens from the first moment of time to the last. And, despite the empirical indeterminacy, they might be equally good for practical purposes: for building bridges or curing disease.
Of course one could still insist that however good these competing theories might be at least one of them would have to be false. After all, the story was that the theories will make logically contradictory claims. But having said that we find ourselves with the awkward conclusion that a false theory might nevertheless be as empirically adequate as a true one. Empirical evidence underdetermines truth.
Thus the collapse of positivism leads directly to worries about "Realism". What good is it to practice empirical methods if they cannot be trusted to lead us to the real truth about the world? Alternatively, what is the point of talking about "the real truth about the world" if it is empirically unknowable and unnecessary for pragmatic success? Or should we say that what is really true is somehow relative to what theory we happen to hold?
Academic philosophers have mulled these issues a lot in the half century since "Two Dogma's". Even so, it seems that most of them have thought these worries were, well, academic.
It is a characteristic relativist claim that, in principle, we can always make up alternative versions of the stories that we tell about the world. But one finds, if one actually tries, that it is surprisingly hard to do so. "Maybe it's all just a dream?" Well, maybe; but how would that explain what holds your glasses up? Explaining, in any detail, why things are as they appear to be is hard; science is our best try so far.... So why all the fuss about the possibility-in-principle of "alternative versions"?
In "Truth", Blackburn himself closes his discussion of underdetermination by saying:
In a way though, this is only a problem for philosophers.... There may be rhetoric about the socially constructed nature of Western science, but wherever it matters, there is no alternative. There are no specifically Hindu or Taoist designs for mobile phones... There are no satellites base on feminist alternatives to quantum theory..." [p. 196]
When we find professional philosophers (of all people!) going out of their way to assure us that an idea is farfetched and we can surely conclude that is wildly irrelevant to any practical concern.
But is it so? Note that both Fodor and Blackburn talk as if disputes between alternative theories can be scientifically irresoluble only if one of them is not "Science" properly so called. (Blackburn suggests they might involve "reading tea leaves" or "crystal balls"..) But there is no basis for this.
The Quinean argument I rehearsed above only works if we assume that the alternatives are both well formed empirical theories and the argument between their advocates a robustly scientific one. You think your experiment shows something remarkable. I think it shows only that your test tubes were dirty. You offer evidence that you washed the test tubes. I retort that your result is the best evidence there could be that your washing was inadequate. This is the form of a perfectly respectable scientific dispute. Both our positions are reasonable. Your remarkable result might be true, but remarkable claims need remarkable evidence and sometimes the test tubes are dirty. And so the argument between us may go back and forth. If Quine is right, it might go on forever. There need be no possible evidence that would settle the issue between us.
But, is this sort of impasse a real life possibility?
I think it happens all the time.
I offer, as a convenient example, the current debate over Anthropogenic Global Warming (AGW). "Convenient" because it happens that Blackburn himself is a Global Warming "denier".
As everyone will know, in the AGW debate there is broad agreement about at least some of the data: that by some measures the world got warmer from about 1970 to about 1998. The AGW theory explains this as the upshot of human generated CO2. Competing theories range from the extra-terrestial (orbital precession, sunspots) to the mundane (the thermometers are measuring urban heat pollution.)
So far this sounds like science-as-usual; Different hypothesis competing to explain some data, let's do some experimenting and may the best hypothesis win! But what is most remarkable about the AGW dispute-- and what I offer as the first bit of evidence that there is more going on here than a merely empirical dispute-- is the degree of confidence with which these competing theories are held by their proponents. Both sides talk as if all requisite data is already in, and that it clearly falsifies the other side.
Thus according to many proponents of AGW "the scientific debate is over" there is an overwhelming scientific consensus about its reality supported by a body of data so compelling that dissenters are the intellectual equivalent of flat-earthers, the moral equivalent of holocaust deniers and probably in the pay of Big Oil.
On the other side? Well here is Blackburn on global warming:
... people’s beliefs are very often swayed by their emotions. But in fact I think the scientific evidence is that the phenomenon is either very slight or doesn’t exist. There is no good measurement of global warming. There are bad measurements of it using land-based, widely-scattered, sporadic, rather primitive instruments called ‘Stevenson Boxes’, often sited near airports and in cities which do indeed show warming, but the globe is much bigger and the best measurements of the atmosphere’s temperature are given by satellites and by meteorological balloons. And if you go to the websites for those, they show more or less flat graphs.
Blackburn's remarks signal that he is an extreme AGW skeptic, one of those who doubts that there really is any warming to be explained away. It's a matter of putting thermometers too close to airports. It is, in effect, dirty test tubes.
But what about that scientific consensus? Blackburn says:
I don’t think it is true of the vast majority of scientists actually. I think what happened is that the environmentalist issues became very, very dominant and a number of bodies were set up. The most influential is the United Nations Intergovernmental Panel on Climate Control (IPCC). They produced a mountain of excellent science, including the measurements I’ve been relying upon, but then there are the public pronouncements. And the public pronouncements have always been much much more alarmist than the measurements actually suggest they should be.
So the IPCC has a "mountain of excellent science" but a theory that somehow amounts to no more than a hill of beans. How can that be? Blackburn blames it on the gutter press and bad actors:
It is remarkable the disparity between the public perception and the newspaper media perception, and the science. But you see I think enough scientists actually have a motive for continuing that mismatch because that’s the way they stay in the limelight and get their funding and their computer time. I’m not saying that’s fraud, I’m just saying it is a mechanism which makes human beings form their beliefs
Read this paragraph again and remind yourself that Blackburn is not dismissing astrology, homeopathy, or creationism. He's dismissing a theory that the President of The Royal Society, Lord Rees, pronounces Settled Science.
These extreme oppositions will be familiar to anyone who has followed this dispute as will the easy willingness on all sides to resort to name calling and ad hominem. Would Blackburn really want to say that Lord Rees is merely "... swayed by his emotions" or is it that he think Rees is in it for the grant money and computer time?
What is going on?
I think it is extremely significant that both sides of this dispute are convinced that the other side is not just wrong but also irrational, venal or plain stupid. I take this confirmation of a conjecture Donald Davidson once made in "On the Very Idea of a Conceptual Scheme".
Quine showed us that our interpretation of the world is always affected by what theory we bring to the evidence. But he had also argued that we cannot interpret other people without making some assumptions about their theory of the world. In making sense of others we must deploy "The Principle of Charity"; that is we must assume that other people are fairly rational and have by and large mostly true beliefs about the world around them. Putting these claims together, Davidson noted that in exercising the Principle of Charity, what we are charitably assuming is that other people mostly share our beliefs and background theory about the world.
What would happen, Davidson asked, if we came across a population of people for whom charity failed? That is people who-- no matter what sense we tried to make of them-- always seemed to be asserting what we took to be glaring falsehoods? In that case, Davidson said, the project of interpretation would break down. We could say these people had a different "conceptual schemes" than us but that would be just a fancy pants way of admitting that they were, to us, wholly incomprehensible. Beyond a certain point we cannot make sense of people who disagree with us about the facts.
I think that this, at moderate scale, is what is going in the AGW debate. When one side finds the other denying the "obvious" relevance of some fact, the principle of charity breaks down. Either the other guy doesn't know what he's saying, or he's too much a fool to be worth talking to. Which is a reasonable position, provided we note that what will seem obvious, or indeed "reasonable", will depend upon one's background theory and different background theories will lead to contrary conclusions about who is and who is not a fool. Thus the unalloyed mutual acrimony of the AGW debate.
I note that one option Davidson ignored-- though it would have served his argument -- was that of supposing the conceptually divergent population really do know The Truth (our Truth!) but are a conspiracy of dissembling con men. And I note that this paranoid style of interpretation is also often adopted by both sides of the AGW debate.
I offer it as a merit of the view I am advocating that it allows us to give full credit to all parties. There are honorable men on both sides (indeed, in Lord Rees case: Right Honorable). Neither side need be counted as irrational or venal or willfully blind to the evidence. Both can be seen to be giving the data its due in good scientific conscience. But the sides are talking past each other because the difference between them cannot be empirically decided.
Just look at the debate: one side points to the warming Arctic . The other points out, with equal triumph, that the Antarctic is getting cooler. One side points to places where sea levels are rising, the other retorts that these are just places where the land is subsiding. There is virtually no longitudinal data invoked on either side that hasn't been extensively "re-calibrated" as they say (if you agree with it) which is to say "fudged" (if you don't) . And so it goes, back and forth in what is, I submit, a perfect acting out of precisely the kind of impasse Quine envisaged.
I expect resistance to this claim. I'm sure some will insist "Look. One way or another this is going to get sorted out. CO2 levels are (alas) going to continue to increase. It will either get warmer or it won't. So eventually the data will decide the facts!"
Really? Well consider that by more or less the same measures that led to the "consensus" that it got warmer after 1970 there is also now more or less general agreement that it has not been getting warmer since about 1998. Ten years of increased CO2 but not much (or any) warming. If this keeps up, won't the case soon be closed? Nope.
“Writing in Nature, the scientists said: "Our results suggest that global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic [manmade] warming."
“Commenting on the new study, Richard Wood of the Hadley Centre said the model suggested the weakening of the MOC would have a cooling effect around the North Atlantic.”
"Such a cooling could temporarily offset the longer-term warming trend from increasing levels of greenhouse gases in the atmosphere."
Any AGW skeptic will read these paragraphs as blatant proof that AGW is screaming pseudo-science. The AGW believer, on the other hand, will hear it as sober scientists refusing to get distracted from the big picture by a little noise in the data. I take no side. I quote it only to show that if you think that time and temperature will settle this empirically you are going to have to wait at least "for the next decade" or, more likely, till Hell freezes over.
Some will protest that I've got it wrong. They will say that the springs of the debate are nothing so exotic as the underdermination of theory by evidence, "It's just politics! The problem just that people are allowing their political views to interfere with climate science proper!"
There is something right and something wrong with this diagnosis.
What's wrong is the idea that there is something called "Climatogy" that can be separated out from our theories about everything else. This ignores Quine's lesson that confirmation is holistic. Just as no single sentence ever confronts the evidence on its own, no set of "purely Climatological" hypothesis can be insulated from the scientist's other beliefs. The climatologist brings to his data not just a climate theory, but also his beliefs about Viking Vinland lore, about the proximity of airports to thermometers, about the fecundity of polar bears, about the sobriety of English Lords... Modulo some ancillary hypothesis, anything he believes about anything might be relevant to his climatological conclusions. "Holism" means the whole enchilada.
On the other hand, suppose that I am correct in thinking that this debate is a case of Quinean underdetermination. What sort of debate is it then? It would seem wrong to call it a "scientific" debate since no amount of science will ever sort it out. And it can’t be an empirical dispute if no empirical evidence could settle it. But then it doesn't seem to be a merely philosophical debate either: there is all that tiresome data.
What to call it? I think we already have a name for it: It is a political dispute.
I do not use that term ironically or with sarcasm. I think most political debates really are empirical disputes conducted in a regime of empirical underdetermination. Political arguments are typically empirically irresoluble disputes between otherwise robustly empirical theories.
Yes. yes. I'm sure that there are some political disputes that arise from fundamental differences of moral principle. But not many. There are, after all, just not that many different moral principles; far too few to explain all the politics in the world.
And, I suppose, some political disputes stem from basic differences in values and preferences. But, I think, not many. All of us want better schools, cleaner air and better health care. Why then is there so much arguing about how to achieve these goals? Partisans on every side will tell you it's the other side's fault: those other guys are ruled by emotion, just won't look at the facts or are plain stupid. Which of course, is sometimes true. But, I think, not often. More often I think the explanation is that observation is theory laden and humans are burdened with different theories. Good theories sometimes, but mutually contradictory; contradictory in ways that no amount of science will ever sort out.
Do I think that people will still be arguing about AGW in hundred years? No. But I do predict that, whether it gets hotter or colder the consensus view in a hundred years will look much more like the upshot of a political compromise or coup than a scientific result.
So, whatever the merits of his climatology, I think Blackburn is wrong to think underdetermination is a "merely philosophical" issue. It is the stuff of daily life. It is the sea in which we all swim. It is the very bane of our existence.
Our collective tragedy is that empirical methods can, in principle, only take us so far. After that, it's all Rush Limbaugh and questions in Parliament.
Let no one accuse me of relativism or anti-realism. Nothing in the forgoing entails that there is no fact of the matter about AGW. I'm happy to say that the theory is either true or it is false, no matter what anyone thinks. But I confess I would be very hard pressed to explain why this matters. It seems, dare I say, a point of purely philosophical interest.
I can already hear this complaint:
"Look if we really took this seriously we would have no reason to suppose that important issues like AGW could ever be rationally resolved even among reasonable people. But that would leave us with no motive to participate in the debate. What would be the point of arguing?
Yours is the counsel of intellectual impotence and despair. If we accept it we would have nothing to do but retire to our beds and succumb to post-modernist funk. "
Quite right! Welcome to my world.