I have found myself thinking more and more lately about the philosophy of science, and finding it increasingly important for the rest of philosophy. There are multiple reasons for this. Perhaps the most important is simply the prestige (or normative weight) we attach to scientific knowledge, a prestige I take to be deserved. I would agree that to the extent that it is fair to say that “science has established” that human consciousness is not reborn after death, then it is true that human consciousness is not reborn after death. Science, in that respect, is what classical Indian philosophers would have called a pramāṇa, a reliable means of knowledge.

A second, related, reason is that it turns out that that very nature of something’s being scientifically established turns out on closer glance to be quite complex, itself its own kind of philosophical question – and one with bearing on philosophical questions well outside the natural sciences. Studies of the history of science – what science has actually been in practice, not what it is supposed to be in theory – show us a process much messier than an account in the standard mold of “build your theory by generalizing from the empirical evidence”. Often the theoretical insight comes first and the observations supporting it come only later. So Copernicus built his heliocentric model mathematically and only later would Galileo demonstrate it with a telescope, just as Einstein began with an “intuition” of the theory of relativity that was only later empirically verified. The way actual science – including the science of our greatest scientific heroes – has proceeded, turns out to be considerably messier than the standard account tells us it is supposed to be.

How then might we think about what science and scientific knowledge are? I have come to notice five different major positions on this question. What is helpful is that these positions appear to me on a spectrum. They range from an orthodox normative position that focuses only on what science should be and ignores what it has been, to a purely descriptive position that jettisons scientific norms entirely. Something seems prima facie wrong about both extremes: to say either that science has no norms to distinguish it from pseudoscience and irrationality, or that science as it has actually been practised is irrelevant to those norms. Rather, the best candidates for an accurate account are in the middle.

A great deal of philosophy of science, especially within early 20th-century analytic philosophy, has focused its attention entirely on the norms of how science is supposed to work. The RationalWiki site effectively defines “philosophy of science” in those terms: “In the practical sense, ‘the’ philosophy of science is almost synonymous with the scientific method – it is the philosophy and ideal that scientists hold and that they believe they should ascribe to.” Typically, this ideal is in some respect inductivist: one is supposed to start by observing nature, preferably with as little contamination from one’s presuppositions as possible, and from there, infer patterns into theories. Inductivism is a long tradition that goes back to Francis Bacon, but has been developed in the twentieth century by analytic philosophers like Carl Hempel.

Those who have studied science as it actually is and has been, however – whether historians, or sociologists like Bruno Latour and Steve Woolgar – have shown that the actual practice of science works nothing like this. Scientists have always started from their existing paradigm – which, if we go back far enough in history, would always at some point have been a “religious” one – and attempted to fit their data to it, or to their “intuitions”. Observation of this history and sociology have led an opposite, radical position that rejects scientific norms entirely. Most notorious of these positions is that of Paul Feyerabend, whose Against Method summed up its position as “anything goes”: science actually has no norms, nor should it. If Feyerabend were right, there would be little reason to prefer Darwinian biology over creationism, the heliocentric cosmology over the geocentric – a position that seems rather too clever by half, one that makes one look like an edgelord.

But one does not have to hew to either extreme. There are at least three major philosophers of science who have sought some form of middle ground – an account of natural science that attempts to allow some room for both the normative ideal of what science should be and the descriptive statement of what it is. These are Karl Popper, Imre Lakatos, and Thomas Kuhn. I think we can fruitfully map philosophies of science on a spectrum from normative to descriptive, Bacon-Popper-Lakatos-Kuhn-Feyerabend. I will speak more next time of the middle ground occupied by Popper, Lakatos and Kuhn.