Platt was frustrated by the fact that some fields of science seem to make clear and rapid progress, while others keep mucking around without seemingly being 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 ought to be to find a way to make them 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. Nonetheless, Platt’s critique of soft science provides us with an excellent starting point to explore the idea that, in fact, there may be more than one kind of science, that “science” is a heterogeneous category, a notion that would surprise many in the general public, and that will likely be resisted by most scientists.
Platt’s attack on soft science begins by stressing the fact that some disciplines seem to make fast and impressive progress, while others have a tendency to go 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 seems more complex than a simple line dividing “hard” from “soft” disciplines: it is true, say, that 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, for instance the long interval between Newton and Einstein, during which little or nothing was known about the intimate structure of matter. 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 now close to a century; as yet, they have not gotten very far.
Organismal biology (ecology and evolutionary biology) is often considered a quasi-soft science, and yet it has seen periods of great activity and 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 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 1952 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 I have just described, and that Platt therefore has a point, next we need to ask why it is so. [This post is a draft excerpt from a chapter of my forthcoming book, "Nonsense on Stilts: How to Tell the Difference Between Science and Bunk," to be published next year by the University of Chicago Press]