In my last post, I tried to describe what is for me a very familiar pattern of intellectual struggle, followed by what feels like understanding, followed by a zealous over application, and then, finally, a more modest re-assessment of the new idea. My best personal example of this phenomenon came with my introduction to the ideas of the philosopher Karl Popper, particularly with regard to the scientific method.
I first met Popper’s work in summary form, in a book called The Great Philosophers, and clearly the professor doing the summarising was a fan. I was hooked both, because the description given was compelling, and also because the central topic, the special nature of scientific enquiry, suited my interests and prejudices. I felt as if I was on the verge of being delivered up a robust intellectual foundation for the things I most wanted to believe.
Later I spent a year at a genetic research centre where Popper’s take on science was central to the ethos of that community. Indeed the two principle academics there had risen to fame many years before by specifically meeting a Popperian challenge to show evolution constituted real science. And that centre was such an exciting and admirable point of intellectual endeavour that my fondness for Popper was always going to blossom.
So I read. I worked my way through The Open Society, The Logic of Scientific Discovery, Conjectures and Refutations, other books whose names I’ve since forgotten. And although the writing style was deceptively accessible, it took work for the ideas to settle, and it was precisely the effort required, plus the desire to believe, that saw me overlook the most obvious weakness. This will make a little more sense if I outline the theory in question.
Popper’s description of the scientific method claimed to be addressing two puzzles, the problem of demarcation (what makes science different from other forms of enquiry?) and the problem of induction (how is it that we are justified in assuming the things we have observed today will continue to hold tomorrow?) In essence, he proposed a single solution to them both. And that solution was falsification. Science is special, he suggested, because it proceeds not by finding support for its theories, but by finding refutations. A theory is scientific if it makes a prediction which, if it doesn’t hold, will show the theory to be wrong. Hence, it is the business of science to generate brave and novel predictions. A new theory makes a prediction not contained in the existing theory, the prediction is tested, and either it holds, so the old theory has been falsified and must be rejected, or it doesn’t hold, and so the new theory has failed to establish itself and can be safely ignored. Popper’s favourite examples included the ability of General Relativity to predict the light-bending properties of mass (tested by measuring the apparent shift of a star’s position when its light passes close to the sun, for which one must wait for an eclipse).
Through falsification, demarcation is made apparently simple. Is this the sort of theory that generates tightly measurable and novel predictions? If yes, science, if not, it’s some other form of knowledge. Popper liked to use examples like Marxism, which by his assessment are not scientific because they give their explanations after the event, twisting the narrative to support the hypothesis.
And induction? Well, Popper suggested science doesn’t use inductive reasoning. Which is to say, we don’t really see a particular relation holding, and then conclude that it will continue to hold into the future, even though it often feels as if this is what we are doing. Rather, all we are saying is that a theory that has not yet been falsified might be true, whereas one that has been falsified is certainly not true (see one black swan, and the hypothesis that all swans are white is no longer viable). And so, by slowly but surely working our way through certainly false propositions, and replacing them with possibly true ones, we are refining our understanding of the world without ever committing to saying anything about whether or not our current propositions will hold into the future.
And this feels like such a satisfying theory. Science is special, because it has a rigour about it that other endeavours do not have. That is not science! one can confidently claim, it is nothing but pseudo-science. Where are its predictions? How can it even be falsified? Although it is never made explicit, the assumption that non-scientific enquiry is in some way inferior is a natural fit with the theory, and the scientifically minded may feel a certain smugness is licensed. And, because the requirements for falsification can be made tremendously narrow, just about any form of knowledge you have reservations about can be dismissed as not real science.
Further, for anybody who has ever worried over the problem of induction (okay, I admit, we’re a small and odd minority) the thought that one can advance knowledge without having to make what is essentially a leap of faith to sustain it, is more than a little appealing. Clearly, in opening up lines of division between those of faith, and those of science, it’s a particularly beguiling offer.
And yes, I was smitten: along for the ride, ready to hurl my insults at those left standing on the roadside . The wheels first wobbled when I tried to describe Popper’s contribution to scientific method in my book Falling for Science. I found that I was forced to use the same few examples again and again, because whenever I tried to apply it to other areas of science I was familiar with, the facts never seemed quite straightforward enough. There was always room for uncertainty and interpretation. As there is in non-scientific endeavour. The line of demarcation was worse than murky and whatever this thing called scientific knowledge was, it was going to be awfully small.
More importantly, even those examples (like the relativity one) appeared to carry their emotional weight not because of the falsification of a rival, but because of the verification of the new theory. Yes, they’re two sides of the same coin, but it’s the power of verification that really impresses us. As, I propose, it should. Because it is verification that gives us the confidence to apply our theories. When we did A and observed B, again and again. Hence we are able to trust this relation, and build technology and future theories upon it. The belief that this sort of relation holds Falsification is important too, one should always be open to negative evidence, but a huge part of the scientific enterprise is interested in verifying what is suspected, rather than attempting to falsify it. Why on earth deny that?
The answer is, because if we are able to frame scientific enquiry purely in terms of falsification, we don’t have to worry about this business of the rules all changing on us tomorrow (this is the problem of induction: just because rocks don’t float today doesn’t imply they won’t float tomorrow, unless you assume that all of our physical laws will extend into the future, and there is no evidence available to support this view, so we do just have to assume).
But even if the rules might change, so the Popperian reasoning goes, we are still confronted with one theory that has already been falsified, and one that hasn’t, and hence the non-falsified is in some sense a better bet. Unfortunately, as soon as we attempt to apply this bet to the future, the wheels come off completely, and this is the gaping hole in the Popperian description of science. We can hypothesis A is a better description than hypothesis B of the world we have experienced, but we can’t predict that it will out perform it tomorrow. If Popper’s description of science is correct, then science is entirely unable to tell us what to expect, ever. Or, as one critic rather wearily put it, ‘when are the Popperians going to admit, that every time they turn the light switch and expect the light to shine, they are contradicting their own theory?’ Or, as someone else said, nothing that is correct about Popper’s description of science is novel, and everything that is novel is incorrect.
And, while Popper’s contribution was undoubtedly important, and gives us new and helpful ways of framing the problems, I now think the critics have a very good point. Yet, how easy was it for me to ignore this? Even when I came across a lecture on youtube, where the academic pointed out precisely this problem, using the decision to get on an airplane as his example, I somehow managed to miss his point. My ignorance had become all but wilful. The trouble, I think, is that learning why a theory doesn’t work is every bit as hard as learning how it does work, and nowhere near as satisfying. It is the difference between climbing the mountain, and returning to home base. All that extra effort, just to find you’re back where you started, only more tired. No wonder we get trapped in error, the views from the top are gorgeous.