Evolving Thoughts

Evolution, culture, philosophy and chocolate! John Wilkins' continuing struggle to come to terms with impermanence... "Humanus sum, nihil humanum a me alienum puto" - Terence

Wednesday, September 22, 2004

Wittgenstein, transformation, and evolution

When Wittgenstein collaborated for a period with Friederich Waismann, the outcome was an unpublished book, Logik, Sprache, Philosophie. He was working his way from the logical atomism of the Tractatus to the holism of the Philosophical Investigations. They wrote:
Our thought here marches with certain views of Goethe's which he expressed in the Metamorphosis of Plants. We are in the habit, whenever we perceive similarities, of seeking some common origin for them. The urge to follow such phenomena back to their origin in the past expresses itself in a certain style of thinking. This recognizes, so to speak, only a single scheme for such similarities, namely the arrangement as a series in time. (And that is presumably bound up with the uniqueness of the causal schema). But Goethe's view shows that this is not the only possible form of conception. His conception of the original plant implies no hypothesis about the temporal development of the vegetable kingdom such as Darwin's. What then is the problem solved by this idea? It is the problem of synoptic presentation. Goethe's aphorism 'All the organs of plants are leaves transformed' offers us a plan in which we may group the organs of plants according to their similarities as if around some natural center. We see the original form of the leaf changing into similar and cognate forms, into the leaves of the calyx, the leaves of the petal, into organs that are half petals, half stamens, and so on. We follow this sensuous transformation of the type by liking up the leaf through intermediate forms with the other organs of the plant.

That is precisely what we are doing here. We are collating one form of language with its environment, or transforming it in imagination so as to gain a view of the whole of space in which the structure of our language has its beginning. [From Ray Monk's biography of Wittgenstein, Ludwig Wittgenstein: The duty of genius, London: Vintage Books, 1990, page 305f]

Compare this to Darwin's treatment of the same issue:
Certainly no clear line of demarcation has as yet been drawn between species and sub-species - that is, the forms which in the opinion of some naturalists come very near to, but do not quite arrive at, the rank of species: or, again, between sub-species and well-marked varieties, or between lesser varieties and individual differences. These differences blend into each other by an insensible series; and a series impresses the mind with the idea of an actual passage. [Origin of Species first edition of 1859, page 45]

The one - Wittgenstein, in the Goethean tradition, indeed the Platonic tradition - sees a formal transformation, where the other - Darwin the naturalist - sees a historical process. That Goethe is looking at parts of the same organism, while Darwin is treating of entire organismic forms of related groups is beside the point - even Wittgenstein and Waismann realise this. Here is the basic tension between the tradition of philosophy in the west, and the science of biology once the Great Chain of Being had been abandoned. And this tension remains.

Taxonomists today are divided (not evenly) between those who think that systematics recovers history (so-called "process" cladists, and "evolutionary" systematists) and those who think it is merely a prologue, on the basis of which hypotheses about history can be tested (the so-called "pattern" cladists, also known as "transformed" cladists, echoing the comment about transformation in Goethe).

Pattern cladists took seriously the notion that arranging organisms in terms of homologies generated groups not historical trees. A cladogram is to them a summary of shared, derived, characters (synapomorphies) and characters that are not derived and are shared, either transformed or not (symplesiomorphies). Colin Patterson, one of the founders of this view, wrote:
"[e]very homology characterizes a group at some level in the hierarchy, and symplesiomorphy and synapomorphy are terms for homologies that stand in hierarchic relation: a symplesiomorphy (general character) makes a group, and a synapomorphy (special character) makes a subgroup. In this light, too, the rift between [pattern] cladists and [phylogenetic] systematists comes clearer into focus." [Patterson 1982, page 305]

The hierarchy is just a summary of these generalities and specialities. But the process cladists automatically assume, or rather many tend to, that the cladogram immediately equates to a historical tree. Cladograms, though, are representations of characters, not events. It is an inference we make that characters give us the sequences in which events of adaptation or speciation occurred. And evolutionary history is an explanation of these facts, which leads some people to wonder if there is some circularity, epistemically speaking. For we use the assumption that evolution occurs in a particular way - that synapomorphies represent one single event subsequently inherited by later taxa.

Now, the epistemological issue is broad-ranging. It goes to the question whether we can recover history from the vestiges and outcomes of the past. This subject had been covered by Sober in his Reconstructing the past of 1988, but the issues are substantially those that were previously covered under the "covering law" model of historical explanation. Historical sciences are a general case of the historical social sciences.

Western philosophy, however, has tended to rate a "presentist" approach to knowledge above a historical approach, on the assumption that real knowledge is of an eternal now. Philosophical problems are treated as if they haven't changed since Plato or earlier, and as if all we have to do is inquire for ourselves, based on our intuitions (which are, by methodological convention, the same at all times and places), in order to sort out conceptual confusion.

Hence Wittgenstein's comment in the Tractatus I quoted in the last blog entry:
Darwin's theory has no more to do with philosophy than any other hypothesis in natural science. (Wittgenstein 1922 4.1122)

Now compare this with a philosopher who was in part the target of Wittgenstein, Russell and Moore - John Dewey, strongly influenced by Darwin:
Old ideas give way slowly; for they are more than abstract logical forms and categories. They are habits, predispositions, deeply engrained attitudes of aversion and preference. Moreover, the conviction persists - though history has shown it to be a hallucination - that all the questions that the human mind has asked are questions that can be answered in terms of the alternatives that the questions themselves present. But in fact intellectual progress usually occurs through sheer abandonment of questions together with both of the alternatives they assume - an abandonment that results from their decreasing vitality and change of urgent interest. We do not solve them: we get over them. Old questions are solved by disappearing, evaporating, while new questions corresponding to the changed attitude of endeavor and preference take their place. Doubtless the greatest dissolvent in contemporary thought of old questions, the greatest precipitant of new methods, new intentions, new problems, is the one effected by the scientific revolution that found its climax in the "Origin of Species." (Dewey 1909: 402)

Taking a historical approach allows us to see that form is an indicator of change. But the problem of the pattern cladists, the Platonists, and the general ideas of western philosophy remains and keeps inserting itself into questions of explanation and classification, in biology and in social science. This will be the subject of the next blog.

Dewey. J., 1909. "The influence of Darwin on philosophy" in Appleman, P. ed. 1970, Darwin: a Norton critical edition W W Norton and Co, NY

Patterson, C., 1982. Cladistics and classification. New Scientist, 94, 303–306.

Sober, Elliott. 1988. Reconstructing the past: parsimony, evolution, and inference. Cambridge, Mass.: MIT Press.

Wittgenstein, Ludwig. 1922. Tractatus logico-philosophicus. London: Kegan Paul, Trench, Trubner & Co.

F.Waismann, Logik, Sprache, Philosophie, G. Baker & B. McGuinness (eds.) (Reclam, 1976)