Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.
Friday, April 15, 2011
Evolution as pseudoscience?
by Massimo Pigliucci
Don't worry, despite the title of this post, I have not suddenly gone creationist. Rather, I have been intrigued by an essay by my colleague Michael Ruse, entitled “Evolution and the idea of social progress,” published in a collection that I am reviewing, Biology and Ideology from Descartes to Dawkins (gotta love the title!), edited by Denis Alexander and Ronald Numbers.
Ruse, who has arguably written more than anyone else on the planet about the history and philosophy of Darwinism, is also contributing to a large collection of new essays on the demarcation problem (the distinction between science and pseudoscience), that Maarten Boudry and I are putting together for the University of Chicago Press (provisional title: The Philosophy of Pseudoscience: Reconsidering the Demarcation Problem — stay tuned).
Ruse's essay in the Alexander-Numbers collection questions the received story about the early evolution of evolutionary theory, which sees the stuff that immediately preceded Darwin — from Lamarck to Erasmus Darwin — as protoscience, the immature version of the full fledged science that biology became after Chuck's publication of the Origin of Species. Instead, Ruse thinks that pre-Darwinian evolutionists really engaged in pseudoscience, and that it took a very conscious and precise effort on Darwin’s part to sweep away all the garbage and establish a discipline with empirical and theoretical content analogous to that of the chemistry and physics of the time.
Ruse asserts that many serious intellectuals of the late 18th and early 19th century actually thought of evolution as pseudoscience, and he is careful to point out that the term “pseudoscience” had been used at least since 1843 (by the physiologist Francois Magendie), while the concept was prominently on display during the historical investigation of mesmerism ordered in 1784 by King Louis XVI of France and jointly carried out by Antoine Lavoisier and Benjamin Franklin.
Ruse’s somewhat surprising yet intriguing claim is that “before Charles Darwin, evolution was an epiphenomenon of the ideology of [social] progress, a pseudoscience and seen as such. Liked by some for that very reason, despised by others for that very reason.”
Indeed, the link between evolution and the idea of human social-cultural progress was very strong before Darwin, and was one of the main things Darwin got rid of. The encyclopedist Denis Diderot was typical in this respect: “The Tahitian is at a primary stage in the development of the world, the European is at its old age. The interval separating us is greater than that between the new-born child and the decrepit old man.” Similar nonsensical views can be found in Lamarck, Erasmus, and Chambers, the anonymous author of The Vestiges of the Natural History of Creation, usually considered the last protoscientific book on evolution to precede the Origin.
On the other side of the divide were social conservatives like the great anatomist George Cuvier, who rejected the idea of evolution — according to Ruse — not as much on scientific grounds as on political and ideological ones. Indeed, books like Erasmus’ Zoonomia and Chambers’ Vestiges were simply not much better than pseudoscientific treatises on, say, alchemy before the advent of modern chemistry.
One of Ruse’s interesting points is that people were well aware of this sorry situation, so much so that astronomer John Herschel referred to the question of the history of life as “the mystery of mysteries,” a phrase consciously adopted by Darwin in the Origin. Darwin set out to solve that mystery under the influence of three great thinkers: Newton, the above mentioned Herschel, and the philosopher William Whewell (whom Darwin knew and assiduously frequented in his youth). Let us take them briefly one by one to see exactly what Ruse means.
Darwin was a graduate of the University of Cambridge, which had also been Newton’s home. Chuck got drilled early on during his Cambridge education with the idea that good science is about finding mechanisms (vera causa), something like the idea of gravitational attraction underpinning Newtonian mechanics. He reflected that all the talk of evolution up to then — including his grandfather’s — was empty, without a mechanism that could turn the idea into a scientific research program.
The second important influence was Herschel’s Preliminary Discourse on the Study of Natural Philosophy, published in 1831 and read by Darwin shortly thereafter, in which Herschel sets out to give his own take on what today we would call the demarcation problem, i.e. what methodology is distinctive of good science. One of Herschel’s points was to stress the usefulness of analogical reasoning (more on this in a moment).
Finally, and perhaps most crucially, Darwin also read (twice!) Whewell’s History of the Inductive Sciences, which appeared in 1837. In it, Whewell sets out his notion that good scientific inductive reasoning proceeds by a consilience of ideas, a situation in which multiple independent lines of evidence point to the same conclusion.
Here is the cool thing: the first part of the Origin, where Darwin introduces the concept of natural selection by way of analogy with artificial selection can be read as the result of Herschel’s influence (natural selection is the vera causa of evolution), while the second part of the book, constituting Darwin's famous “long argument,” applies Whewell’s method of consilience by bringing in evidence from a number of disparate fields, from embryology to paleontology to biogeography.
What, then, happened to the strict coupling of the ideas of social and biological progress that had preceded Darwin? While he still believed in the former, the latter was no longer an integral part of evolution, because natural selection makes things “better” only in a relative fashion. There is no meaningful sense in which, say, a large brain is better than very fast legs or sharp claws, as long as you still manage to have dinner and avoid being dinner by the end of the day (or, more precisely, by the time you reproduce).
Ruse’s claim that evolution transitioned not from protoscience to science, but from pseudoscience, makes sense to me given the historical and philosophical developments. It wasn’t the first time either. Just think about the already mentioned shift from alchemy to chemistry. Of course, the distinction between pseudoscience and protoscience is itself fuzzy, but we do have what I think are clear examples of the latter that cannot reasonably be confused with the former, SETI for one, and arguably Ptolemaic astronomy. We also have pretty obvious instances of pseudoscience (the usual suspects: astrology, ufology, etc.), so the distinction — as long as it is not stretched beyond usefulness — is interesting and defensible.
It is amusing to speculate which, if any, of the modern pseudosciences (cryonics, singularitarianism) might turn out to be able to transition in one form or another to actual sciences. To do so, they may need to find their philosophically and scientifically savvy Darwin, and a likely bet — if history teaches us anything — is that, should they succeed in this transition, their mature form will look as different from the original as chemistry and alchemy. Or as Darwinism and pre-Darwinian evolutionism.