The uneasy relation between philosophy and biology 2
The history of research into the philosophy of language is full of men (who are rational and mortal animals), bachelors (who are unmarried adult males), and tigers (though it is not clear whether we should define them as feline animals or big cats with a yellow coat and black stripes). [Umberto Eco, Kant and the Platypus (Vintage, 1999) page 9]
This is, in a way, old news. Biologists have been complaining about how philosophers treat variation in the living world since Mayr announced that essentialism is dead in taxonomy:
Typological thinking finds it easy to reconcile the observed variability of the individuals of a species with the dogma of the constancy of species because the variability does not affect the essence of the eidos [the Greek term translated as "species"] which is absolute and constant. Since the eidos is an abstraction derived from human sense impressions, and a product of the human mind, according to this school, its members feel justified in regarding a species "a figment of the imagination," an idea. [Mayr, Ernst. 1957. Species concepts and definitions. In The species problem: A symposium presented at the Atlanta meeting of the American Association for the Advancement of Science, December 28–29, 1955 (Publication No 50, edited by E. Mayr. Washington DC: American Association for the Advancement of Science), page 12])
He then of course affirmed that "species" in biology is quite different, a gene pool rather than a class of objects. Ironically, the early nineteenth century writers, such as Mill, knew from their Locke that real species had variation that logical classes did not. One widely used textbook was that of the Archbishop of Dublin, Richard Whatley, The Elements of Logic, published in 1826, and by the time of the Origin in its 9th edition. Whatley notes, for example, that the logical sense of "species" is quite distinct from the sense in which naturalists use it of “organized beings" (Bk IV, ch. 5 §1), for they are real things, “unalterable and independent of our thoughts" (p183):
... if anyone utters such a proposition as ... "Argus was a mastiff," to what head of Predicables would such a Predicate be referred? Surely our logical principles would lead us to answer, that it is the Species; since it could hardly be called an Accident, and is manifestly no other Predicable. And yet every Naturalist would at once pronounce that Mastiff, is no distinct Species, but is only a variety of the Species Dog. ...
... the solution of the difficulty is to be found in the peculiar technical sense ... of the word "Species" when applied to organized Beings: in which case it is always applied (when we are speaking strictly, as naturalists) to individuals as are supposed to be descended from a common stock, or which might have so descended; viz. which resemble one another (to use M. Cuvier’s expression) as much as those of the same stock do.
Whatley knew that species varied in ways logical species didn't. So why is it that modern philosophers are so ill-equipped to deal with biology? It has to do, I believe, with the development largely in English-speaking philosophy of logical empirical method, primarily in Russell and Moore (see Suzanne Cunningham's review for a comprehensive look at how this arose).
British philosophy had been idealist up until this point, and in reaction to it, Russell and Moore drew on Hume, who had been brought to the attention of the philosophical community again by a review by Thomas Henry Huxley (yes, that Huxley), published in 1879. The philosophical method used was one of logical argument, begun afresh by any rational enquirer. It was therefore ahistorical - Plato was treated as if he had just now made his arguments, along with Aristotle, Berkeley, Spinoza and so on. And science was not the foundation of any philosophy, but philosophy was to be the foundation for science.
In part this was also a reaction to the over-simplistic appeal to science, including evolutionary biology, by a number of philosophers such as Herbert Spencer, who blithely assumed that "more evolved" meant "better", and for which George E. Moore developed his characterisation of the "Naturalistic Fallacy", the idea that any natural (that is, physical) property was to be identified with The Good that Socrates had said was the aim of philosophy to characterise.
Moore's and Russell's student, friend and ultimately successor was Ludwig Wittgenstein. As part of the "logicist" movement, developed by Gottlob Frege, in which mathematics was to be founded on the fundamental terms of logic (meaning, symbolic logic) Wittgenstein wrote what is now the most famous modern philosophical text, the Logische-Philosophische Abhandlung, translated into English as the Tractatus Logico-Philosophicus, which similarly used the ahistorical reflective method. In it, he said:
Darwin's theory has no more to do with philosophy than any other hypothesis in natural science. (Tractatus 1922 4.1122)
But he maintained this position even when he developed his later thoughts, which he considered to be a rebuttal of the Tractatus. Just before that comment, he had said "Psychology is no nearer related to philosophy, than is any other natural science", but this view he did change, and his remarks on psychology became the foundation for his entire later thought. So, why did evolution continue to remain philosophically off-limits?
The answer is to be found in a work he tried to produce in concert with the logical positivist Frierich Waismann - entitled Logik, Sprache, Philosophie. We'll look at this next. It has some interesting resemblances - family resemblances? - to issues of modern systematics in biology.
Cunningham, Suzanne. 1996. Philosophy and the Darwinian legacy. Rochester: University of Rochester Press.
Huxley, T.H. 1879. Hume. London: McMillan and Co.