Science is not about certainty

curryja

12 years ago

by Judith Curry

I seem to be saying two things that contradict each other. On the one hand, we trust scientific knowledge, on the other hand, we are always ready to modify in-depth part of our conceptual structure about the world. But there is no contradiction, because the idea of a contradiction comes from what I see as the deepest misunderstanding about science: the idea that science is about certainty. — Carlo Rovelli

The Edge has a Conversation with Carlo Rovelli, entitled Science is not about certainty: a philosophy of physics. (h/t Michael Cunningham).

Some bio info on Rovelli: CARLO ROVELLI is a theoretical physicist, working on quantum gravity and on foundations of spacetime physics. He is professor of physics at the University of the Mediterranean in Marseille, France and member of the Intitut Universitaire de France. He is the author of The First Scientist: Anaximander and His Legacy; and Quantum Gravity.

Some excerpts from Rovelli’s essay (read the whole essay for his perspective on the history science and modern physics):

We teach our students: we say that we have some theories about science. Science is about hypothetico-deductive methods, we have observations, we have data, data require to be organized in theories. So then we have theories. These theories are suggested or produced from the data somehow, then checked in terms of the data. Then time passes, we have more data, theories evolve, we throw away a theory, and we find another theory which is better, a better understanding of the data, and so on and so forth.

This is a standard idea of how science works, which implies that science is about empirical content, the true interesting relevant content of science is its empirical content. Since theories change, the empirical content is the solid part of what science is. Now, there’s something disturbing, for me as a theoretical scientist, in all this. I feel that something is missing. Something of the story is missing. I’ve been asking to myself what is this thing missing? I’m not sure I have the answer, but I want to present some ideas on something else which science is.

This is particularly relevant today in science, and particularly in physics, because if I’m allowed to be polemical, in my field, in fundamental theoretical physics, it is 30 years that we fail. There hasn’t been a major success in theoretical physics in the last few decades, after the standard model, somehow. Of course there are ideas. These ideas might turn out to be right. Loop quantum gravity might turn out to be right, or not. String theory might turn out to be right, or not. But we don’t know, and for the moment, nature has not said yes in any sense.I suspect that this might be in part because of the wrong ideas we have about science, and because methodologically we are doing something wrong, at least in theoretical physics, and perhaps also in other sciences.

When I give a thesis to students, most of the time the problem I give for a thesis is not solved. It’s not solved because the solution of the question, most of the time, is not solving in the question, it’s just questioning the question itself. Is realizing that in the way the problem was formulated, there was some implicit prejudice assumption that was the one to be dropped.If this is so, the idea that we have data and theories, and then we have a rational agent that constructs theories from the data using his rationality, his mind, his intelligence, his conceptual structure, and juggles theories and data, doesn’t make any sense, because what is being challenged at every step is not the theory, it’s the conceptual structure used in constructing theories and interpreting the data. In other words, it’s not changing theories that we go ahead, but changing the way we think about the world.

What are then the aspects of doing science that I think are under-evaluated, and should come up-front? First, science is about constructing visions of the world, about rearranging our conceptual structure, about creating new concepts which were not there before, and even more, about changing, challenging the a-priori that we have. So it’s nothing to do about the assembly of data and the way of organizing the assembly of data. It has everything to do about the way we think, and about our mental vision of the world. Science is a process in which we keep exploring ways of thinking, and changing our image of the world, our vision of the world, to find new ones that work a little bit better.The past knowledge is always with us, and it’s our main ingredient for understanding. The theoretical ideas which are based on ‘let’s imagine that this may happen because why not’ are not taking us anywhere.Science is not about certainty. Science is about finding the most reliable way of thinking, at the present level of knowledge. Science is extremely reliable; it’s not certain. In fact, not only it’s not certain, but it’s the lack of certainty that grounds it. Scientific ideas are credible not because they are sure, but because they are the ones that have survived all the possible past critiques, and they are the most credible because they were put on the table for everybody’s criticism.

The very expression ‘scientifically proven’ is a contradiction in terms. There is nothing that is scientifically proven. The core of science is the deep awareness that we have wrong ideas, we have prejudices. We have ingrained prejudices. In our conceptual structure for grasping reality there might be something not appropriate, something we may have to revise to understand better. So at any moment, we have a vision of reality that is effective, it’s good, it’s the best we have found so far. It’s the most credible we have found so far, its mostly correct.

If I can make a final comment about this way of thinking about science, or two final comments: One is that science is not about the data. The empirical content of scientific theory is not what is relevant. The data serves to suggest the theory, to confirm the theory, to disconfirm the theory, to prove the theory wrong. But these are the tools that we use. What interests us is the content of the theory. What interests us is what the theory says about the world. General relativity says space-time is curved. The data of general relativity are that Mercury perihelion moves 43 degrees per century, with respect to that computed with Newtonian mechanics.

Who cares? Who cares about these details? If that was the content of general relativity, general relativity would be boring. General relativity is interesting not because of its data, but because it tells us that as far as we know today, the best way of conceptualizing space-time is as a curved object. It gives us a better way of grasping reality than Newtonian mechanics, because it tells us that there can be black holes, because it tells us there’s a Big Bang. This is the content of the scientific theory.

So summarizing, I think science is not about data; it’s not about the empirical content, about our vision of the world. It’s about overcoming our own ideas, and about going beyond common sense continuously. Science is a continuous challenge of common sense, and the core of science is not certainty, it’s continuous uncertainty. I would even say the joy of taking what we think, being aware that in everything we think, there are probably still an enormous amount of prejudices and mistakes, and try to learn to look a little bit larger, knowing that there is always a larger point of view that we’ll expect in the future.

This may take me to another point, which is should a scientist think about philosophy, or not? It’s sort of the fashion today to discard philosophy, to say now we have science, we don’t need philosophy. I find this attitude very naïve for two reasons. One is historical. Just look back. Heisenberg would have never done quantum mechanics without being full of philosophy. Einstein would have never done relativity without having read all the philosophers and have a head full of philosophy. Galileo would never have done what he had done without having a head full of Plato. Newton thought of himself as a philosopher, and started by discussing this with Descartes, and had strong philosophical ideas.

But even Maxwell, Boltzmann, I mean, all the major steps of science in the past were done by people who were very aware of methodological, fundamental, even metaphysical questions being posed. When Heisenberg does quantum mechanics, he is in a completely philosophical mind. He says in classical mechanics there’s something philosophically wrong, there’s not enough emphasis on empiricism. It is exactly this philosophical reading of him that allows him to construct this fantastically new physical theory, scientific theory, which is quantum mechanics.

The divorce between this strict dialogue between philosophers and scientists is very recent, and somehow it’s after the war, in the second half of the 20^th century. It has worked because in the first half of the 20^thcentury, people were so smart. Einstein and Heisenberg and Dirac and company put together relativity and quantum theory and did all the conceptual work. The physics of the second half of the century has been, in a sense, a physics of application of the great ideas of the people of the ’30s, of the Einsteins and the Heisenbergs.

I think that the scientists who say I don’t care about philosophy, it’s not true they don’t care about philosophy, because they have a philosophy. They are using a philosophy of science. They are applying a methodology. They have a head full of ideas about what is the philosophy they’re using; just they’re not aware of them, and they take them for granted, as if this was obvious and clear. When it’s far from obvious and clear. They are just taking a position without knowing that there are many other possibilities around that might work much better, and might be more interesting for them.

I think there is narrow-mindedness, if I might say so, in many of my colleague scientists that don’t want to learn what is being said in the philosophy of science. There is also a narrow-mindedness in a lot of probably areas of philosophy and the humanities in which they don’t want to learn about science, which is even more narrow-minded. Somehow cultures reach, enlarge. I’m throwing down an open door if I say it here, but restricting our vision of reality today on just the core content of science or the core content of humanities is just being blind to the complexity of reality that we can grasp from a number of points of view, which talk to one another enormously, and which I believe can teach one another enormously.

JC comment: This essay resonated with me, since I am struggling to understand why climate science doesn’t seem to me to be working so well. Apart from the politicization of climate science, which has torqued the science in unfortunate ways, I have an (unformulated) sense that we are missing something in the way we are approaching this very complex scientific problem. The schism between philosophy and science is arguably one of the problems. I have been grappling with this issue in an ad hoc way: at Climate Etc., there have been over 30 posts with the tag ‘scientific method‘, and scads more about uncertainty. Some of you have little patience for this type of post, and are hard core empiricists (‘show us the data’). But making progress on any scientific issue (especially one as complex as climate change) requires much more than data, and I hope that Rovelli’s essay provokes you to think more broadly about this topic.

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