Avery's "Neurotic Reluctance"

AVERY'S "NEUROTIC RELUCTANCE' ARTHUR M. DIAMOND, JR.* Stephen Toulmin pioneered a major advance in the philosophy of science when he demonstrated how examples from the history and present practice of science could be relevant to the philosopher's enterprise [I]. In his most recent major contribution, Human Understanding, Toulmin uses examples from the history of science to illustrate his central claim that science often advances through changes "in the very criteria of 'rationality' " [2]. The claim is a crucial one because, if true, it implies that, if science is rational at all, it is only "rational" in a much weaker sense than scientists have believed and philosophers have hoped. The plausibility ofToulmin's claim rests heavily on the three examples he cites from the history of science. Each of them deserves careful attention , but here I will focus on the second: Oswald Avery's "almost neurotic reluctance" to identify DNA with genes. Toulmin's one-page account [2] depends almost exclusively on a paper by Perspectives in American History editor Donald Fleming [3]. As a result, any criticism of Toulmin's page is even more a criticism of Fleming's paper. For Toulmin, however, the account assumes an importance that it never had for Fleming. In Fleming, the account is part ofa survey ofthe effects of the emigration of German scientists due to the rise of the Nazis. In Toulmin, however, the account is central evidence for a crucial generalization about science, namely, that scientific criteria of rationality are not stable and universal. By Toulmin's account, "biochemical questions about the material nature of the gene were unimportant, if not entirely irrelevant," to Avery and his colleagues because of "their commitment to the currently accepted attitudes of classical genetics." The result, according to Toulmin, was that Avery's classic 1944 paper was, in Fleming's words, "muffled and circumspect." Avery and his coauthors were (here Toulmin again»Department of Economics, Ohio State University, 1775 College Road, Columbus, Ohio 43210.© 1982 by The University of Chicago. All rights reserved. 0031-5982/83/2601-0286$01.00 132 I Arthur M. Diamond,Jr. ¦ Avery's "Neurotic Reluctance" quotes Fleming) " 'almost neurotically reluctant' to identify genes with DNA" [2]. What made advance in biology possible was the entry into the field of the new physicist-biologists such as Astbury, Delbrück, and Szilard. These men held different criteria of rationality in science, for they, unlike Avery and his colleagues, valued "a radical physical explanation " of biological phenomena [2]. Such is the account of Toulmin's second example. If the account is accurate, then the example seems to provide good evidence of the changeability of the criteria of scientific rationality. The question is whether the account is accurate. In the remainder of this note, two grounds for doubting the accuracy of the account will be explored: (1) that Avery's reluctance has been exaggerated and (2) that to the extent that the reluctance existed, it arose from criteria Avery shared with the physicist-biologists. Toulmin, quoting Fleming [3, p. 152], claims that Avery was "almost neurotically reluctant to identify genes with DNA." As evidence for the claim, Fleming quotes a sentence from Avery in which he admitted that substances other than DNA may possibly be involved in genetic transformation . But Fleming does not quote the following sentence in which Avery says, "If . . . the biologically active substance isolated in highly purified form as the sodium salt ofdeoxyribonucleic acid actually proves to be the transforming principle, as the available evidence strongly suggests, then nucleic acids of this type must be regarded not merely as structurally important but as functionally active in determining the biochemical activities and specific characteristics of pneumococcal cells" [4]. This statement hardly shows "neurotic reluctance," especially when considered in the light of the good reasons Avery had for qualifying his claim. Further, if there was, in fact, such reluctance, we would expect it to be reflected in Avery's private correspondence either as resistance to the identification of DNA with genes or at least as depression at the necessity of making such an identification. On the contrary, when he writes to his brother, Avery is delighted at the possibility that DNA is...