15 Nov 2009

Evolutionary Nonsense. Creative Evolution. Bergson. Ch.1 Part 10. Darwin and Insensible Variation

by Corry Shores
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Evolutionary Nonsense

Henri Bergson

Creative Evolution

Évolution Créatrice

Chapter 1

The Evolution of Life – Mechanism and Teleology

Chapitre Premier

De l’évolution de la vie. – Mécanisme et finalité.

10. Darwin and Insensible Variation

10. Darwin et la variation insensible

Many different species share similar features. For example, animals of all sorts have very similar organs. But the species' lines of evolution diverged before they developed these organs. Somehow the species evolved them independently. And yet they are strikingly similar. So it is probably not a coincidence. Bergson used this as grounds for his own creative theory of evolution. It says that there is a universal impetus that is responsible for these similarities between divergently-evolved species. He previously gave 2 examples: both plants and animals reproduce sexually, and many species have similarly structured eyeballs, even though they developed them independently. A mechanistic theory of evolution would say that evolutionary changes are random, and those most adapted to the species’ circumstances will be passed-on. There are two varieties of this theory. Darwin is responsible for the first one. He says that variations are very small and gradual. They are ‘insensible variations.’ The other kind are sudden. Hugo de Vries gave this account.

§67 Evolutionary Teething

Bergson now looks specifically at the theory that evolution happens gradually by means of insensible variations. It assumes that chance causes variations in the species traits, and they accumulate gradually.

Now, let’s note that something like an eyeball functions only on account of its many coordinated mechanisms. And also consider this: if a species evolves an organ that does not function, it probably will not be passed-on. Yet, for something like an eyeball to function, very many parts would have to all appear concurrently: “the minute structure of the retina may develop, and however complicated it may become, such progress, instead of favouring vision, will probably hinder it if the visual centres do not develop at the same time, as well as several parts of the visual organ itself” (67d). But how could all the many delicate and finely-coordinated parts of an eye all by coincidence appear at the same time? Darwin saw that this was unlikely, and so he proposed his theory of insensible variations; for, “a difference which arises accidentally at one point of the visual apparatus, if it be very slight, will not hinder the functioning of the organ; and hence this first accidental variation can, in a sense, wait for complementary variations to accumulate and raise vision to a higher degree of perfection” (68b). Nonetheless, Bergson objects. Sure, one tiny variation in the eye could form without that hindering the other parts. However, it would also not help them either. So if it does not contribute to the organism's function, why then would that organisms be favored in natural selection? One possible answer is that evolution adds little parts that will later be added-upon. [Bergson likens such a variation to a pierre d'attente, which is translated as a “toothing stone.” It seems that pierres d'attente are stones that jut-out of the edge of a wall, so that the wall might be continued at a later time. See the images below.]

But such a theory would suggest that the coming developments are presupposed in the prior ones. This is not compatible with the Darwinian thesis that the variations are random. Yet, in order to understand how both the mollusk and vertebrate eyes are so similar [see §64], we would need to suppose that the evolutionary development already had tendencies like these masonry protrusions, as though the variations expected that they would later be built-upon.

From the English translation:

From the original French:

Bergson, Henri. L'Évolution Créatrice. Ed. Felix Alcan. Paris: Librairies Félix Alcan et Guillaumin Réunies, 1908. Available online athttp://www.archive.org/details/levolutioncreatr00berguoft

Bergson, Henri. Creative Evolution. Transl. Arthur Mitchell. London: MacMillan and Co., 1922. Available online at:http://www.archive.org/details/creativeevolutio00berguoft

Picture from:
Thank you Claude Lothier.

Diagram from:

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