Claude Bernard, 1813--1878

31 Oct 1997 13:23

Bernard's three great claims on posterity are that he was one of the founders of proper, experimental physiology; that he was, if not the first, then one of the first to recognize the importance of the "internal environment" of the organism; and that he was an excellent methodologist.

In physiology, much that he insisted upon --- experimentation, careful checking, controls, the application of physics and chemistry --- now seems obvious, but it met with a fair degree of opposition, some of it from people who thought that if you just observed nature without interference she'd give up her secrets, some of it from people who felt experimenting on animals was cruel. (These latter included Bernard's wife, which did not make for a happy home life, but did tend to keep him, productively, in the laboratory.) I think it's safe to say that no one worth arguing with would claim that a Goethian biology has much going for it, so Bernard won on that score, at least; and we're still arguing about animal experimentation. (Bernard, incidentally, was not strictly a materialist, as he was accused of being, since he allowed some special properties to living things, having to do with their being "harmonious," but insisted that they had to obey all the usual laws of physics and chemistry just the same. One wonders what he would have made of liquid crystals.)

Bernard seems to have been led to the idea of the internal environment by one of his methodological pillars, which was strict determinism. Yet, as the First Harvard Law of Behaviorism states, "Under precisely controlled experimental conditions, the test animal does as it damn well pleases." The obvious solution is that the determining conditions are not all in the exterior of the animal, but on the inside as well --- the condition of its blood, hormone levels, internal temperature, etc., etc. through most of the contents of Physiology 1. If mechanisms exist to keep the internal environment constant, you can snap your fingers at changes wrought on the external environment. As he famously said, "The fixity of the internal environment is the condition for free life." (This is often quoted without a source or an original, which I find annoying, so here is mine: La fixité du milieu intérieur est la condition de la vie libre; Oevures xvi, 113 = Phénomènes de la vie, tome i, cited in J. M. D. Olmstead, Claude Bernard, Physiologist (NY: Harper & Brothers, 1938), p. 254.) This idea, without which, as I've said, most of what organisms do hardly makes sense, is obviously very useful to biology, especially in its more developed form, as the notion of "homeostasis", and it was also one of the roots of the modern notion of feedback, and so of cybernetics, at least in its early days when it was worthwhile. It is through this route that he influenced Herbert Simon's notion of an artifact, though apparently only indirect, since I can find no mention of Bernard in The Sciences of the Artificial.

One might call homeostatic devices "Bernard Machines", by analogy with Turing, von Neumann and Darwin Machines, and it would be interesting to know if there are adaptors which are neither Bernard Machines nor Darwin Machines. (I've heard it suggested that Bernard Machines are a special case of Darwin Machines, with deviations from the stable regions being treated as varieties which are selected against, but I don't think this works, since variation would have to always be in the direction of higher fitness, and that's against the rules. The difference between positive and negative feedbacks is also important here, I think.)

Finally, his methodology was broadly positivist and, I think, broadly correct; perhaps more importantly, it seems to be the sort of thing scientists spontaneously develop. Ideas should be formulated in such a way that they can be subjected to experimental tests; which tests, if properly and stringently conducted, can suffice to rule out hypotheses, but never definitely establish them. (Popper, in our own day, has been emphatic on the importance of this point.) The purpose of experiment and observation is to test hypotheses, and so the hypothesis is logically prior to the observation. Induction plays no role in this; hypotheses may be suggested by whatever one likes, and the connection of a hypothesis with its experimental consequences is a matter of deductive logic (including mathematics) alone. (In fact, Mills's canons of induction, for instance, look a lot more like rules for testing hypotheses than for arriving at them.) Strict determinism he regarded as essential to science, and while it's certainly a useful guiding assumption, it cannot be maintained all the time, in which case we must fall back on statistics. Bernard, it must be said, did not trust statistics at all; whether this was justified in view of the state of the art, or whether he just didn't understand them properly, I couldn't say. (He does, however, have some very amusing passages against stupid uses of statistics in biology.) Outside the circle of experimental ideas lie mere formal truths (and falsehoods), things which are true (or false) by virtue of the way we have agreed to use signs, and purely metaphysical ideas, for which we can never have good grounds to give or withhold assent. (I hasten to add that Bernard always expressed the high respect for certain metaphysicians, especially Descartes, and regarded contemplating metaphysics as a useful mental exercise; i.e. he did not go so far as the logicial positivists and declare the whole lot rubbish, though this seems to have been more a matter of temperament than anything else.)

As I said, this is a view of scientific method that scientists, especially experimenters, tend to quite naturally, at least in their day-to-day work, even if they've been taught some other methodology, and will repeat that to you when you ask them about method explicitly. I think this is significant, though it hardly means that it's right, since scientists may be at least as prone to self-delusion as, say, poets or politicians, who are notorious for not understanding what they are doing. I can't resist thinking, however, that Bernard had grabbed hold to some essentially right notions about how to do science --- though I can't think of an experimental test for this.