Unsettled science — knowledge and certainty
Mark Vernon recently posted three quotations on his excellent blog Philosophy & Life.
The first was from physicist Carlo Rovelli: “The notion of ‘scientifically proven’. Nearly an oxymoron. The very foundation of science is to keep the door open to doubt.”
The second was from another physicist, Lawrence Krauss: “Indeed, no number, no measurement, no observable in science is exact… Until we can quantify the uncertainty in our statements and our predictions, we have little idea of their power or significance.”
The last was from Neil Gershenfeld, the director of MIT’s Center for Bits and Atoms:
“The most common misunderstanding about science is that scientists seek and find truth. They don’t — they make and test models.”
I linked to Mark’s post, adding the comment, “Guess it isn’t settled, after all.” I was thinking, of course, about all those assertions as to the science being settled regarding what used to be called global warming, but is now referred to as climate change.
It turns out I should have read the quotes in context. Krauss, for instance, also said, “The fact that global warming estimates are uncertain, for example, has been used by many to argue against any action at the present time.” From this I infer that he is certain about “the fact of global warming.”
Rovelli also had more to say: “Are we sure that the Earth is going to keep heating up, if we do not do anything? Are we sure of the details of the current theory of evolution? Are we sure that modern medicine is always a better strategy than traditional ones? No we are not, in none of these cases. But if from this lack of certainty we jump to the conviction that we better not care about global heating, that there is no evolution and the world was created six thousand years ago, or that traditional medicine must be more effective than the modern medicine, well, we are simply stupid.”
He is apparently not sure that “the Earth is going to keep heating up,” but he seems pretty sure we should care enough about it to do something about it.
None of this would bother Gershenfeld, I imagine, because he goes on to say that “Truth is a model.” It bothers me, though, because it makes me suspect that none of these people thinks very clearly.
To begin with, they all have a very loose sense of what it means to be certain. The word derives from a French word meaning “sure, reliable, fixed, settled, determined.” So if the estimates, as Krauss puts it, are “uncertain,” it means we can’t be sure of them, because they are not reliable. And we’re talking of them now as estimates, not as facts. In other words, they are not even approximately certain.
To compare not knowing all of “the details of the current theory of evolution,” as Rovelli does, to doing something just in case the Earth really is getting steadily warmer seems disingenuous, since we’re a hell of a lot more certain about evolution (at least when confined to the origin of species) than we are as to what the temperature will be a century or more from now. As to whether you’d prefer to have your broken leg set by a physician or chanted over by a shaman, I suspect few people would have a hard time making up their minds about that. (I might add that you can think that all the details about evolution have not been worked out and not ever entertain the notion that the world was made in six days. His own words indicate that Rovelli himself does that all the time.)
It’s one thing to say that science is never “settled,” that new information can come along to challenge even our most cherished notions. It’s quite another to give the impression that it’s all more or less guesswork. Exactness and certainty are by no means the same thing. Rovelli knows that perfectly well: “Knowledge itself is probabilistic in nature, a notion emphasized by some currents of philosophical pragmatism. Better understanding of the meaning of probability, and especially realizing that we never have, nor need, ‘scientifically proven’ facts, but only a sufficiently high degree of probability, in order to take decisions and act, would improve everybody’s conceptual toolkit.” Well, yes. And it is — dare I day it? — precisely the degree of probability that is at issue when it comes to something like global warming, especially since gazillions of dollars also figure in the equation.
I am far more certain — and I’m willing to bet that Rovelli, Krauss and Gershenfeld are as well — that poverty and hunger throughout the world are real than I am of global warming claims. I also submit that there is a higher probability that we can deal with those successfully than there is of pulling off planetary climate control any time soon.
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BRAVO AND WELL SAID!
Precisely right. It’s all about probability, and the ability of the vaunted models to predict what’s happening in climate. So far their performance does not lead to confidence.
Indeed. I am suspicious of the integrity of climate models.
I go one step further: the more certain experts claim to be, the less I’m likely to trust them.