The only event that I am certain occurred in 1962 was the initial publication of Thomas Kuhn’s marvelous book, The Structure of Scientific Revolutions. It is noteworthy for (if I may engage in what I presume to be some Whig history of my own) breaking philosophy of science free from the last vestiges of logical positivism. Kuhn paints theory choice as a much more complicated (and hence rather more interesting) matter than mere head-to-head comparison of which theory objectively accounts for “the evidence” better. The notion that science might be an interesting, social activity that couldn’t be performed by soulless machines of course raised the hackles of illiterates everywhere, who took the book to be an argumentative defense of irrationalism. (And numerous intelligent philosophers were illiterate in this fashion. Lakatos, for instance, thought Kuhn had reduced theory choice to “mob psychology”. While Lakatos has powerful real critiques of Kuhn, that particular claim seems to me reflexive defensiveness of the sort that philosophers really ought to analyze before letting it into their public work.)
The charge of illiteracy is a bit unfair—but only a bit. There is one aspect of Kuhn’s book that does seem to be heavily irrationalist: his notion of incommensurability. (And it is no surprise that Feyerabend, a true ir- or at least non-rationalist, picked up on and developed this notion to his own ends.) Unfortunately, Kuhn’s notion of incommensurability is terribly unclear in The Structure of Scientific Revolutions, and it’s hard to know what to make of it. The basic idea, though, is this: because competing theories use the same terms with different meanings (e.g. “mass” under the Newtonian and Einsteinian paradigms), there is no way to map between the language of one theory to the language of another. There is a failure of translation between theories. Scientists within competing paradigms are speaking different languages, and despite appearances, they talk past one another. Kuhn also sometimes connects incommensurability to the role (he thinks) value judgments play in theory choice, but this seems to me a mistake, since he later explicitly dissociates value judgments (about which rational debate is possible) from matters of taste (de gustibus non est disputandum). Kuhn eventually makes his unfortunate conversion metaphor: when a scientist adopts a new paradigm, it requires a conversion experience. Feyerabend’s notion of incommensurability is distinct from Kuhn’s, but shares the central conclusion that conversation between competing theories is impossible.
There are two reasons why even this point does not save the Kuhn-as-irrationalist reading. First, Kuhn clearly does think that the progress of science is rational. He does not think it is cumulative, and does not think it converges on truth, but he certainly does think that it is, on a collective level, rational. What he challenges is that rationality dictates when individual scientists must change between paradigms. Second, incommensurability is only one element of the book, and while undoubtedly the most controversial, it is surely not the most important. The book paints a picture of science as rational that cuts against narrow views of rationality (for instance, views that countenance only individual, but not collective, rationality), but not against rationality as a whole.
Nevertheless, the incommensurability thesis is a central, problematic part of Kuhn’s book, and it is wrong. Donald Davidson’s brilliant “On the Very Idea of a Conceptual Scheme” illustrates why there cannot be incommensurable conceptual schemes in principle, and Philip Kitcher’s “Theories, Theorists, and Theoretical Change” illustrates in practice how translation between theories may in fact be enacted. Numerous other challenges exist, and of course neither of those papers is universally considered definitive (being, after all, philosophy papers), but these two illustrate why a rejection of logical positivism need not lead us to the incommensurability thesis, and they do so for both principled and practical reasons, and thus complement each other nicely.
That is a long introduction, perhaps too long, but I am now in a position to suggest that, while not terribly helpful in the philosophy of science, Kuhn was on to something with his notion of incommensurability. My thesis is: there exist cases where translation is not in principle impossible, but where the possibility of translation in the moment is screened by particular features of the case. Of course, every good thesis has a case study; I take for mine John Cheever’s story, “The Country Husband”. At the beginning of this story, there is a case of practical incommensurability.
By incommensurability here I don’t mean simply cases where communication is problematic because people ignore the perspective of the other. I mean something more robust: because of certain features of the situation, features that go on mere personal stubbornness and unwillingness, prevent the gulf between two perspectives from being bridged. Thus practical incommensurability is a special way of failing to communicate.
“The Country Husband” is a rich, long story (tied for the longest in The Stories of John Cheever) with numerous threads. I isolate only a small strand of the story, and I hope to be clear that what I am doing here is not providing an interpretation of the story. I am using this small strand to make a point orthogonal to Cheever’s story as a work of art. Francis Weed is in a “plane crash” (more accurate: the plane is in a storm and has to make an emergency landing). When he comes home, he attempts to share this story with his family: “ ‘Hi everybody,’ he said. ‘The plane from Minneapolis…’ “ (327). As we are told, nine times out of ten he “would be greeted with affection, but tonight the children are absorbed in their own antagonisms.” His news cannot reach his children, because they are wrapped up in other activities. So far, this is not incommensurability in the sense I am talking about. It is merely a failure of communication.
A bit later, Francis and his eldest daughter Helen are sitting at the table, and Francis tries to tell her about the plane crash (she was in her room when he first got home). However, “she doesn’t understand about the plane crash, because there wasn’t a drop of rain in Shady Hill” (328). Here is a case of genuine incommensurability. Helen is faced with a certain narrowness of empathy, an inability to extend her own perspective enough to understand her father. There is no clear way for Francis to translate the situation for her—indeed we have learned earlier (when he tried to explain his situation to an adult as he headed home), that “Francis had no powers that would let him re-create a brush with death” (326).
Because the narrowness of perspective is simply a function of the fact that he is talking to a child, this is a less interesting case of incommensurability. I bring it up because it is a clear case where translation is impossible, not for principled reasons, but because of Francis’ descriptive powers and Helen’s narrow empathy. I think that the bedlam that begins “The Country Husband” reveals a deeper sort of incommensurability, where an initial failure of communication can create a feedback loop that creates practical barriers to communication that can only be overcome by a sort of “conversion”.
Return to Francis’ arrival home. The plane crash is of course weighing on his mind, but he is not able to express this to anyone because they are wrapped in their own perspectives. This initial failure of communication frustrates him and further wraps him up in himself. His children are fighting as children fight, and this escalates until each of the children is hurt (physically or emotionally or both) and resentful, and the children are thereby consumed by their own troubles. Once they sit down at the table for dinner, skirmishes break out again, and Francis, for whom this is the last thing he needs, asks his wife (Julia) if the kids might not have dinner before he gets home. Julia becomes defensive, and the scene breaks down.
At the beginning of this chain, we have a mere failure to communicate. By the end, we have pandemonium and, I suggest practical incommensurability. The initial failure to communicate makes the plane crash weigh heavily on Francis, and his failure to get sympathy for it leads to an inability to consider his wife’s perspective, and so he makes an unreasonable request. His wife, irritated by the squabbling of her kids and by an earlier disagreement with her husband (he accused her of spoiling one of their children), and not knowing about the plane crash (Francis has only tried to tell the kids), is in no position to consider why he would make such a request. And hence there is a deluge of crying and a paucity of understanding. Nothing is resolved; it just ends.
I suggest that this is a case of incommensurability in the practical sense. There is a positive feedback loop where the initial failure of communication, caused because no one did step back from their own concerns, created a situation where no one could so step back, at least not without strenuous effort. An initial gulf with a clear bridge spanning it widens because no one takes that bridge. The bridge that initially existed is no longer long enough, and falls in. All that remains is the abyss.
This feedback loop only builds as the story progresses, and creates a third (and the most interesting) instance of incommensurability. Francis becomes attracted to his children’s babysitter, and it is clear that his infatuation comes in part because there is some hole he thinks she can fill (“what harm could there be in a tryst that would make them both feel more kindly toward the world?” 344), a yawning chasm that opened in the first scene. Is there any reason to think Francis would have been thus infatuated had he been able to get the plane crash off his mind and into the social space of family conversation, if he had been able to transmute the crash from a weight to a story he had to tell? Well, Anne Murchison (the babysitter) is beautiful, but is that enough? I see nothing to suggest it is. (I should note that there is another cause of the attraction, but since it does not affect my point I will leave it to readers to discover for themselves.)
The relationship with Anne amounts to nothing, physically, a mere two kisses is all. Part of the reason for this lies in circumstances outside of Francis’ control: Anne goes home from babysitting early one night, a vagrant child wanders in on their second kiss, Anne is engaged, and so on. But it is ultimately Francis’ choice, too. The “what harm could there be” line I quoted comes near the end of the story, when Francis is deliberating about how to proceed (rape, Church confession, and getting drunk are three of the options that occur to him). Here we see Francis stepping back—it might seem that he has (rationally) broken out of the cycle of incommensurability and is now weighing the options even-handedly. But this is not so. For immediately after he lists the options, he starts justifying his infatuation, and I now quote in full: “It was his life, his boat, and, like every other man, he was made to be the father of thousands, and what harm could there be in a tryst that would make them both feel more kindly toward the world?” This is not reasoning between options. It is rationalizing a predetermined decision.
And then comes the crucial moment. With no reasoning, no deliberation, Francis “converts”. The next sentence: “This was the wrong train of thought, and he came back to the first, the psychiatrist.” Not argument, just this is wrong. This is a conversion experience. Francis suddenly sees the problems with pursuing Anne, despite the solution it offers to other problems. Further, he sees the solutions that his marriage offers—the problem with pursuing Anne is precisely how it will disrupt these solutions. And so Francis sees the psychiatrist, takes up woodworking, things return to normal, and “Francis is happy” (345).
This third case looks the most like Kuhn’s description of conversion in theory choice (and I have described it in language that brings this out). Kuhn emphasized that scientific life is specifically life, a way of living, and the scientists choosing between paradigms are choosing between different ways of living. One way offers solutions to some problems but not others; the other way offers solutions where the former stumbled, but only at the expense of giving up some of its sure solutions. The question then is: which problems matter? And further, which problems matter is something that is determined by which theory you hold, so there is no way to arbitrate the matter. You can only, at some point, convert.
This may not hold for scientific practice, but it does seem to be a good description of certain situations, if only in a practical (rather than principled) sense. Francis could have evaluated the options before him rationally, at least in principle, but his infatuation created a practical barrier: when he tried to reason he got sucked into thoughts that would justify his infidelity by the very lights of that infatuation. The only way he could escape this was to have a sudden moment of seeing that (not why) this was wrong. Hence I think it fair to conclude that Francis was subject to practical incommensurability.