Published online by Cambridge University Press: 14 March 2022
In several recent publications, Professor Adolf Grünbaum has inveighed against the conventionalism of writers like Einstein, Poincaré, Quine and especially Duhem. Specifically, Grünbaum has assailed the view that a single hypothesis can never be conclusively falsified. Grünbaum claims that the conventionalists’ insistence on the immunity of hypotheses from falsification is neither logically valid nor scientifically sound. Directing the weight of his argument against Duhem, Grünbaum launches a two-pronged attack. He insists, first, that conclusive falsifying experiments are possible, suggesting that Duhem's denial of such experiments is a logical non-sequitur. He then proceeds to show that, more than being merely possible, crucial falsifying experiments have occurred in physics. I do not intend to make a logical point against Grünbaum's critique so much as an historical and exegetical one. Put briefly, I believe that he has misconstrued Duhem's views on falsifiability and that the logical blunder which he discusses should not be ascribed to Duhem, but rather to those who have made Duhem's conventionalism into the doctrine which Grünbaum attacks. Whether there are any writers who accept the view he imputes to Duhem, or whether he is exploiting “straw-men” to give weight to an otherwise trivial argument is an open question. For now, I simply want to suggest that his salvos are wrongly directed against Duhem.
1 Cf. Grünbaum's “The Duhemian Argument,” Philosophy of Science, 27 (1960), 75-87; “Laws and Conventions in Physical Theory,” in Current Issues in the Philosophy of Science (ed. Feigl & Maxwell), 140-155, 161-168; Philosophical Problems of Space and Time, 106-152; and “The Falsifiability of Theories: Total or Partial ? A Contemporary Analysis of the Duhem-Quine Thesis,” in Boston Studies in the Philosophy of Science (ed. Wartofsky).
2 Cf. Duhem's Aim and Structure of Physical Theory (trans. Wiener), Part II, chapter vi and passim. The translation is based on the 1914 edition of La Théorie Physique: Son Object—Sa Structure.
3 Grünbaum agrees that crucial experiments cannot verify hypotheses. Like Duhem, he is opposed to the Baconian theory of crucial experiments. But, like Popper and against Duhem, he wants to assert that crucial falsifying experiments occur.
4 Grünbaum readily grants that by suitable logical gyrations, or by a re-definition of terms, one could always find ad hoc some A′ such that for a given O, H + A′ → O. (The simplest way, of course, would be to take O itself as A′.) But he rightly points out that Duhem's point becomes trivial on such an interpretation. Thus, Grünbaum argues that the Duhemian position requires that there exists a non-trivial A′ for every H and every O.
5 Philosophical Problems of Space and Time, 114.
6 For example, Duhem writes that “The physicist can never subject an isolated hypothesis to experimental test, but only a whole group of hypotheses; when the experiment is in disagreement with his predictions, what he learns is that at least one of the hypotheses constituting the group is unacceptable and ought to be modified; but the experiment does not indicate which one ought to be changed.” Aim and Structure, p. 187.
Elsewhere, he notes that “To seek to separate each of the hypotheses of theoretical physics from the other assumptions on which it rests in order to subject it in isolation to observational tests is to pursue a chimera …” Ibid., p. 200.
7 Thus, Grünbaum writes: “Duhem's thesis is that the falsifiability of the hypothesis H as an explanans of the actual empirical facts O′ is always unavoidably inconclusive.” “Laws and Conventions in Physical Theory,” in Current Issues in the Philosophy of Science, p. 145.
8 As further evidence for the ‘weaker’ reading of Duhem, we might consider his discussion in Aim and Structure, Part II, Chapter iv, §10. There he explains that when a theory, T, is falsified, a scientist has two options: he can either modify one of the hypotheses in T to make it compatible with the phenomena, or he may discard the whole structure T and opt for an altogether different theory T′. If Duhem accepted the stronger version of the D-thesis, he presumably would have argued that the former alternative is always open. But he does not take this approach. He does say that we have no “right to condemn in advance the boldness” (p. 217) of the physicist who seeks to preserve his theory in the face of embarrassing evidence. But, on the other hand, Duhem admits that there is no guarantee that he will be successful in finding an A′. The scientist who takes this ploy is justified only if he succeeds in “satisfying the requirements of experiment” (p. 217), i.e., only if he finds some A′ that saves the theory T. Duhem is not asserting that A′s will always be found, or even that they exist, if they are not found. He readily admits that if, after a thorough analysis, no A′s are forthcoming, then we should give up the entire theoretical system, T. But in giving it up, we must be careful not to say that the individual hypotheses within the theory have been falsified. The theory is no longer fruitful, but that does not mean that all its component hypotheses are false.