My colleague Jon Mandle has been looking at John Rawls 1950 doctoral dissertation, A Study in The Grounds of Ethical Knowledge. Jon asked me about a section in which Rawls contrasts ethical theory and scientific theory. The philosophy of science that he presumes is really just background. Yet he discusses what is now often called the Duhem-Quine Problem, a couple of years before Quine's "Two Dogmas of Empiricism". So where did Rawls get it from?
I did not have a good answer to this, beyond the obvious suggestion. So I decided to share the interesting bit here.
Some historical context: After coming back from service in World War II in the mid 1940s, Rawls began graduate work at Princeton. He spent a year at Cornell, where he interacted with Norman Malcolm and Max Black. Although he did not defend his disseration until February 1950, it was completed by about Fall 1948. (He had funding which was contingent on him still being a student.) So the bit here reflects philosophy of science as he was taught it at Princeton and Cornell in the mid to late 1940s.
The obvious answer, suggested by the footnote, is that he got his philosophy of science primarily from Max Black at Cornell. If you have other ideas as to who he might have learned philosophy of science from, please mention them in the comments.
One crucial distinction between the use of a theory in natural science, as opposed to its use in ethics, is that in the former the subject matter is the empirical laws expressed by different causal relations, and whenever the theory does not explain these the theory must be modified; whereas in the latter, the subject matter is the rational judgements of reasonable men, and while we have defined them to be coercive over a theory in the preliminary stage of inquiry, they can be altered, if reasonable men wish to do so; and they may want to change them should they discover that a few recognized judgments are not in harmony with some general principles which explicate most of their other judgments, and which seem to be justifiable. While an explication could hardly cause us to change all our judgments, it may, after we have reflected upon it, cause us to change some of our opinions. Therefore, not only may an ethical theory provide an answer where there is a genuine conflict, and so where there is no opinion at all; but it may actually change some accepted appraisal which was originally considered a part of the subject matter.
Thus an adequate and comprehensive ethical theory may have a control over its data which we generally do not allow to a theory in a natural scienoe. We cannot think that physical processes, having found that Newton's theory explained much of their behavior, would voluntarily agree to act in a manner conformant to its predictions. But in ethical theory this is just what may, and does, happen. Consider, for exanple, the argument of a reformer. He points out that an accepted moral judgment, or an accepted pattern of moral behavior, actually conflicts with a principle which explicates most of our best and soundest opinions. He appeals to us to recognise that such and such a judgment or pattern of conduct violates the principles which underly our common morality. He urges us to bring those discordant judgments and modes of conduct into line. This we can do; and this is a point at which the final use of an ethical theory may be so different from the final use of a theory in the natural sciences.
It may be objected to this difference that it is not so great as I have stated it. Scientific theories control their data, and exercise a coercive power over observations. For example, if an observer were to report that he had seen a body grow hotter in surroundings of lower temperature; or that he had seen all the molecules of a gas collect in a small volume at one end of a container; or that he had watched a heavy body float up in the air; - we should, on the basis of well-confirmed theories, strongly doubt his observations. We should use the evidenced strength of certain physical theories to argue that it is more probable that the observer is mistaken than that the recorded events have happened as he describes. A theory may be so generally accepted that it will throw out numerous reports on similar grounds. This is why, for example, miracles of one kind or another are not scientifically acceptable. It is more likely that the report of a miracle is false than that the theory it contradicts is mistaken. Naturally there is a limit as to how far a theory can discard observations relevant to it. Otherwise, it would not be a theory at all, but an opinion stubbornly maintained in the face of contradicting reports. But, by and large, the general rule obtains that a widely successful theory will serve to discard the few and scattered observations against it; and this is because we take it as more probable that the reports are mistaken than that the theory is incorrect. A theory is refuted by showing that there is a general law which is directly contrary to it; and a few random reports are not sufficient to show this.[footnote; see below]
Thus, while it is true that physical theory may control its data, the relation is entirely different from that which may exist between an ethical theory and its data. In the physical case, it is a question of weighing probabilities, and, in view of a satisfactory theory, there must be strong doubt as to whether a reported event contradictory to the theory eer occurred. But not so with an ethical theory: No one doubts that the common sense jugments contradicting an explication happen every day. We egrant, of course, their existence, but demand, in the light of the explication, that they be changed. This can be done, men being what they are. Ethical theory can have a distinctive control over its data; and it is part of its value that it can have this control, since it then can serve as a means for the reform and improvement of common morality.
[footnote:] The subject matter of a natural science like physics is, primarily, laws, which are stated, when the science is developed, in mathematical terms. If not, they may be called routines. See the discussion in Campell, Physics; the elements, Ch. 4. Or, as Feigl says, the 'Erkenntnisziel' of physics in the 'gesetzliche Gerust dar Welt', of Theorie und Erfahrung in die Physik, 16-18. Thus to refute a theory we must establish a law contradicting it. Popper, in Logik der Forschung, made an attempt to avoid the overstrict criterion of meaning then held by the Vienna Circle by urging that a theory be considered meaningful if it could be conclusively falsified. This test, he thought could be carried. out strictly, since he believed that a finite number of observations could refute a theory. But Black, in a review, exposed the fallacy: "...no scientific law is rejected on the basis of a finite number of contrary observations unless it is believed that the number of such observations could be indefinitely extended by any competent observer under similar conditions; strictly unique experiments, however discordant with theory, are neglected because their uniqueness guarantees their irrelevance: their importance is merely that of the inexplicable." 45 Mind 105 (1936).