A remarkable parallel, which to my knowledge has never been noticed, obtains between the facts of social evolution and the mental growth of the race, on the one hand, and of zoîlogical evolution, as expounded by Mr. Darwin, on the other. (James, 1880, p. 441)
. . . new conceptions, emotions, and active tendencies which evolve are originally produced in the shape of random images, fancies, accidental outbirths of spontaneous variation in the functional activity of the excessively unstable human brain, which the outer environment simply confirms or refutes, preserves or destroys--selects, in short, just as it selects morphological and social variations due to molecular accidents of an analogous sort. . . .
The conception of the [newly discovered scientific] law is a spontaneous variation in the strictest sense of the term. It flashes out of one brain, and no other, because the instability of that brain is such as to tip and upset itself in just that particular direction. But the important thing to notice is that the good flashes and the bad flashes, the triumphant hypotheses and the absurd conceits, are on an exact equality in respect of their origin. (James, 1880, pp. 456-457)
? I do not see how any one with a sense for the facts can possibly call our systems immediate results of 'experience' in the ordinary sense. Every scientific conception is in the first instance a 'spontaneous variation' in one's brain. For one that proves useful and applicable there are a thousand that perish through their worthlessness. Their genesis is strictly akin to that of the flashes of poetry and sallies of with to which the instable brain paths equally give rise. But whereas the poetry and wit (like the science of the ancients) are their 'own excuse for being' and have to run the gauntlet of no further test, the 'scientific' conceptions must prove their worth by being 'verified'. This test, however, is the cause of their preservation, not that of their production. (James, 1890, p. 665)
It follows that an animal cannot be stimulated to make specific antibodies, unless it has already made antibodies of this specificity before the antigen arrives. It can thus be concluded that antibody formation is a selective process and that instructive theories of antibody formation are wrong. (Jerne, 1967, p. 201)
Looking back into the history of biology, it appears that wherever a phenomenon resembles learning, an instructive theory was first proposed to account for the underlying mechanisms. In every case, this was later replaced by a selective theory. Thus the species were thought to have developed by learning or by adaptation of individuals to the environment, until Darwin showed this to have been a selective process. Resistance of bacteria to antibacterial agents was thought to be acquired by adaptation, until Luria and Delbrück showed the mechanism to be a selective one. Adaptive enzymes were shown by Monod and his school to be inducible enzymes arising through the selection of preexisting genes. Finally, antibody formation that was thought to be based on instruction by the antigen is now found to result from the selection of already existing patterns. It thus remains to be asked if learning by the central nervous system might not also be a selective process; i.e., perhaps learning is not learning either. (Jerne, 1967, p. 204)
Pursuing these analogies even further, we might now ask whether one can distinguish between instructive and selective theories of learning in the central nervous system. Looking back into the history of biology, it appears that wherever a phenomenon resembles learning, an instructive theory was first proposed to account for the underlying mechanisms. In every case, this was later replaced by a selective theory. Thus the species were thought to have developed by learning or by adaptation of individuals to the environment, until Darwin showed this to have been a selective process. Resistance of bacteria to antibacterial agents was thought to be acquired by adaptation, until Luria and DelbrÅck showed the mechanism to be a selective one.31 Adaptive enzymes were shown by Monod and his school to be inducible enzymes arising through the selection of pre-existing genes.32 Finally, antibody formation that was thought to be based on instruction by the antigen is now found to result from the selection of already existing patterns.
It thus remains to be asked if learning by the central nervous system might not also be a selective process; i.e., perhaps learning is not learning either.
Several philosophers, of course, have already addressed themselves to this point. John Locke held that the brain was to be likened to white paper, void of all characters, on which experience paints with almost endless variety.33 This represents an instructive theory of learning, equivalent to considering the cells of the immune system void of all characters, upon which antigens paint with almost endless variety.
Contrary to this, the Greek Sophists, including Socrates, held a selective theory of learning. Learning, they said, is clearly impossible. For either a certain idea is already present in the brain, and then we have no need of learning it, or the idea is not already present in the brain, and then we cannot learn it either, for even if it should happen to enter from outside, we could not recognize it. This argument is clearly analogous to the argument for a selective mechanism for antibody formation, in that the immune system could not recognize the antigen if the antibody were not already present. Socrates concluded that all learning consists of being reminded of what is pre-existing in the brain.34 (Jerne, 1967, pp. 204-5)
I hold that in all cases of inductive inference we must invent hypotheses until we fall upon some hypothesis which yields deductive results in accordance with experience.
It would be an error to suppose that the great discoverer seizes at once upon the truth or has any unerring method of divining it. In all probability the errors of the great mind exceed in number those of the less vigorous one. Fertility of imagination and abundance of guesses at truth are among the first requisites of discovery; but the erroneous guesses must be many times as numerous as those which prove well founded. The weakest analogies, the most whimsical notions, the most apparently absurd theories, may pass through the teeming brain, and no record remain of more than the hundredth part. There is nothing really absurd except that which proves contrary to logic and experience. The truest theories involve suppositions which are inconceivable, and no limit can really be placed to the freedom of hypothesis.(quoted in Campbell, 1974b, p. 428)
[HOME] [NEXT]Inspired by the accomplishments of Darwinian evolution in nature, scientists are now beginning to take evolution into their own hands. Evolution is being carried out in the laboratory, not at the level of the organisms or even at the level of cells but at the level of individual macromolecules. The products of these experiments in evolution are molecules exhibiting properties that conform to the demands of the experimenter. (Joyce, 1992, p.190)