Strong inference and the distinction between soft and hard science, part I

In doing some research for my next book (on the differences between science and pseudoscience), I re-read this rather stunning piece of writing: “Scientists these days tend to keep up a polite fiction that all science is equal. Except for the work of the misguided opponent whose arguments we happen to be refuting at the time, we speak as though every scientist's field and methods of study are as good as every other scientist's, and perhaps a little better. This keeps us all cordial when it comes to recommending each other for government grants.” Candid words about the nature of the scientific enterprise as seen from the inside by a participating scientist. And what makes these sentences even more remarkable is that they were not uttered behind close doors in a room full of smoke, but printed in one of the premiere scientific magazines in the world, Science. It was 1964, the year I was born, and the author was John R. Platt, a biophysicist at the University of Chicago. The debate between scientists on what constitutes “hard” (often equated with good, sound) and “soft” (implicitly considered less good) science has not subsided since.

Platt was frustrated by the fact that some fields of science make clear and rapid progress, while others keep mucking around without seemingly been able to accomplish much of relevance. As Platt put it, in the same article: “We speak piously of ... making small studies that will add another brick to the temple of science. Most such bricks just lie around the brickyard.” Physics, chemistry and molecular biology are considered by Platt (and many others) as hard sciences, the quintessential model of what science ought to be. Ecology, evolutionary biology, and even more, fields like psychology and sociology, are soft sciences, and the maximal aspiration of people working in these fields is assumed to be to find a way to make their disciplines as hard as physics. Platt’s article is a classic that should be read by anyone interested in the nature of science, and he was right in pointing out the problem; he was not quite as right in diagnosing its roots however, and even less so at suggesting a possible cure.

Platt’s attack on soft science began by stressing the fact that some disciplines seem to make fast and impressive progress, while others have a tendency of going around in circles, or at best move slowly and uncertainly. Before we examine why this is and what could possibly be done about it, a more fundamental question is whether Platt is correct at all in identifying the existence of a problem. It seems clear from even a cursory examination of the history of science that Platt is at least partially correct: some sciences do progress significantly more than others. However, the pattern appears more complex than a line dividing “hard” from “soft” disciplines: it is true that, say, particle physics and molecular biology have made spectacular advances during the 20th century; but it is also true that physics itself went through long periods of stasis on certain problems, for instance the long interval on the question of the nature of gravity between Newton and Einstein. And such periods of slow progress may occur again in the future, even for “the queen” of sciences: for all the talk about a “unified theory of everything,” physicists have been trying to reconcile the known discrepancies between their two most successful theories, general relativity and quantum mechanics, for close to a century; they have not succeeded yet.

Organismal biology (ecology and evolutionary biology) is often considered a quasi-soft science, and yet it has seen periods of great progress -- most obviously with Darwin during the second half of the 19th century, and more recently during the 1930s and 40s. Moreover, there is currently quite a bit of excited activity in both empirical and theoretical evolutionary biology, which may be leading to another major leap forward in our understanding of how organisms evolve and adapt to their environments. Molecular biology, on the other hand, hailed by Platt as a very successful hard science on the model of chemistry and physics, may be in the process of running into the limits of what it can achieve without falling back on “softer” and more messy approaches to its subject matter: it is true that the discovery of the structure of DNA in 1953 is one of the all-time landmarks of science; but it is equally clear that the much-touted sequencing of the whole human genome has provided very few hard answers for biologists, instead leading to a large number of “bricks laying around the brickyard,” as Platt would have put it. We know a lot more about the human (and other) genomes, but much of what we know is a complex mess of details that is difficult to extricate and to make into a clear picture of how genomes work and evolve.

All in all, it seems that one can indeed make an argument that different scientific disciplines proceed at dramatically different paces, but it is also true that the very same science may undergo fits and starts, sometimes enjoying periods of steady and fast progress, at other times being bogged down into a spell of going nowhere, either empirically (lack of new discoveries) or theoretically (lack of new insights).

If we agree that the nature of science is along the lines that I have just described, next we need to ask why it is so. Platt briefly mentions a number of possibilities, which he dismisses without discussion, but that we need to pay some attention to before we move to his main point. These alternative hypotheses for why a given science may behave “softly” include “the tractability of the subject, or the quality of education of the men [sic] drawn into it, or the size of research contracts.” In other words, particle physics, say, may be more successful than ecology because it is easier (more tractable), or because ecologists tend to be dumber than physicists, or because physicists get a lot more money for their research than ecologists do.

The second scenario is rather offensive (to the ecologists at least), but more importantly there are no data at all to back it up. And it is difficult to see how one could possibly measure the alleged differential “education” of people attracted to different scientific disciplines. Nearly all professional scientists nowadays have a Ph.D. in their discipline, as well as years of postdoctoral experience at conducting research and publishing papers. It is hard to imagine a reliable quantitative measure of the relative difficulty of their respective academic curricula, and it is next to preposterous to argue that scientists attracted to certain disciplines are smarter than those who find a different area of research more appealing. It would be like attempting to explain the discrepancy between the dynamism of 20th century jazz music and the relative stillness of symphonic (“classical”) music by arguing that jazz musicians are better educated or more talented than classically trained ones. It’s a no starter.

The other factors identified and readily dismissed by Platt, though, may actually carry significant weight. The obvious one is money: there is no question that, at least since World War II, physics has enjoyed by far the lion’s share of public funding devoted to scientific research, a trend that has seen some setback in recent years (interestingly, after the end of the Cold War). It would be foolish to underestimate the difference that money makes in science (or anything else, for that matter): more funds don’t mean simply that physicists can build and maintain ever larger instruments for their research (think of giant telescopes in astronomy, or particle accelerators in sub-nuclear physics), but perhaps equally important that they can attract better paid graduate students and postdoctoral associates, the lifeblood of academic research and scholarship. Then again, of course, money isn’t everything: our society has poured huge amounts of cash, for instance, into finding a cure for cancer (the so-called “war” on cancer), and although we have made much progress, we are not even close to having eliminated that scourge -- if it is at all possible.

Part of the differential ability of scientific disciplines to recruit young talent also deals with an imponderable that Platt did not even consider: the “coolness factor.” While being interested in science will hardly make you popular in high school or even in college, among science nerds it is well understood (if little substantiated by the facts) that doing physics, and in particular particle physics, is much more cool than doing geology, ecology or, barely mentionable, any of the social sciences -- the latter a term that some in academia still consider an oxymoron. The coolness factor probably derives from a variety of causes, not the least of which is the very fact just mentioned that there is more money in physics than in other fields of study, as well as the significant social impact of a few iconic figures, like Einstein (when was the last time you heard someone being praised for being “a Darwin”?).