Image: Ludwik Fleck as prisoner / scientist in Buchenwald
An earlier post opened a discussion of the "historical turn" in the philosophy of science in the early 1960s (link). This innovation involved two large and chiefly independent features: deep attention to the social and institutional context of scientific research, and the intriguing idea that research communities give rise to specific "mentalities" or conceptual schemes that are distinctive to that community. The previous post focused on the social and institutional contexts of science. Here I am interested in unpacking the second point about the specialized conceptual schemes and mental frameworks of scientific research communities.
This dimension of the sociological approach to the history of science has primarily to do with the mental frameworks of the practitioners. Here I am referring to the thinking, concepts, and practices of the practitioners within a give area of scientific research. This is the idea that participants in a research community develop shared mental or cognitive frameworks and conceptual schemes on the basis of which to organize their research and theories about the domains they study. It is sometimes argued that these schemes are to some extent incommensurable across research communities (as Kuhn sometimes maintained), leading to the difficulty or impossibility of genuine communication across research traditions. The guiding intuition is that the scientists' conceptual schemes are embedded in an extended social discourse within the research community, and the meanings (and even references) associated with key scientific terms differ systematically from one research community to the other. Important examples include Thomas Kuhn's conception of a paradigm (link), Imre Lakatos's conception of a research programme, or Ludwik Fleck's conception of a "thought collective" (link).
Let's first consider Kuhn's claims about incommensurability across scientific paradigms. (Oberheim and Hoyningen-Huene's article on incommensurability in the Stanford Encyclopedia of Philosophy is very helpful; link.) The idea of a paradigm is somewhat unclear in the original version of Structure of Scientific Revolutions. In its narrow meaning a paradigm is simply a clear example or illustration of something -- for example, a well-designed chemistry experiment. ("This is how you separate heavy water from common H20.") But more commonly Kuhn uses the concept of paradigm more broadly, intending to refer to the heterogeneous mix of material and cognitive practices shared by a scientific research tradition -- laboratory procedures, theoretical concepts, methodological principles, dissemination practices, ideas about the use of evidence and experimental data, and so on. In the 1969 postscript to SSR Kuhn refines his language of paradigm to refer to a "disciplinary matrix". A disciplinary matrix is "an entire theoretical, methodological, and evaluative framework within which scientists conduct their research" (174). The implication is that if one has acquired his or her intellectual reflexes within a discipline, each statement within the science will have a meaning that is affected by other elements of the framework.
(It is worth noting that this point about the dependency of the meaning of a theoretical sentence on a myriad of other commitments and concepts is similar to Quine's explanation in Word and Object of the underdetermination of theory and the indeterminacy of translation: the "meanings" of individual sentences can be adjusted according to the status of other assertions in the web of belief. In Quine's example: in the presence of a certain common small animal, I refer to "rabbit", you refer to "gavagai", and we cannot determine whether gavagai refers to the "individual whole animal" that I have in mind, or your own conceptual scheme of "undetached rabbit parts".)
Here is the first place that Kuhn refers to incommensurability in SSR. The concept arises in discussing successive schools of scientific thought such as Ptolemy and Copernicus:
What differentiated these various schools was not one or another failure of method—they were all “scientific”—but what we shall come to call their incommensurable ways of seeing the world and of practicing science in it. Observation and experience can and must drastically restrict the range of admissible scientific belief, else there would be no science. But they cannot alone determine a particular body of such belief. An apparently arbitrary element, compounded of personal and historical accident, is always a formative ingredient of the beliefs espoused by a given scientific community at a given time. (3)
A hundred pages later he returns to the topic of paradigm incommensurability:
As a result, the reception of a new paradigm often necessitates a redefinition of the corresponding science. Some old problems may be relegated to another science or declared entirely “unscientific.” Others that were previously nonexistent or trivial may, with a new paradigm, become the very archetypes of significant scientific achievement. And as the problems change, so, often, does the standard that distinguishes a real scientific solution from a mere metaphysical speculation, word game, or mathematical play. The normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone before. (103)
It should be noted that Kuhn's claims of incommensurability generally comes with qualifications. It is not a general claim of radical mutual unintelligibility across scientific research communities, but rather a claim about the impossibility of perfect and exact translation: "After he has done so [stepped from the old paradigm to the new] the world of his research will seem, here and there, incommensurable with the one he had inhabited before. This is another reason why schools guided by different paradigms are always slightly at cross-purposes" (111). The highlighted phrases demonstrate the intended softening of the claim.
The claim of incommensurability certainly seems to be a view about the mental constructs -- ideas, concepts, ways of evaluating claims -- that scientists use in their theories and their empirical and experimental practices. Kuhn, and later Feyerabend, seem to assert that participants in competing paradigms of the "same" subject matter see the world differently, and cannot fully agree or disagree with each other about apparently fundamental statements about the world. The classical physicist "parses" the physical world differently than does the relativistic physicist. And these mental schemes are conveyed to the young physicist through his or her training in the discipline; they are only partially formalized in the apparatus of scientific knowledge. In Michael Polanyi's formulation, they are a form of "tacit knowledge": “the aim of a skillful performance is achieved by the observance of a set of rules which are not known as such to the person following them”; Polanyi, Personal Knowledge: 49. Ways of viewing a laboratory across paradigms are sufficiently different that it requires a "gestalt shift" for a scientist to view the world through the alternative theoretical constructs. All of this sounds "mental".
(Here again Quine's views of semantics in Word and Object and "Ontological Relativity" are relevant. Quine seeks to undermine the "museum myth" of sentence meanings. "Uncritical semantics is the myth of a museum in which the exhibits are meanings and the words are labels. To switch languages is to change the labels" (186).)
Now let's turn to a scientist-philosopher whose work influenced Kuhn's, Ludwik Fleck. (A prior discussion of Fleck's work can be found here.) Fleck was a Polish scientist who offered a similar view of scientific conceptual spaces in 1935 in Genesis and Development of a Scientific Fact (1979/1935). Fleck was a medical researcher, and he developed his view of scientific concepts and research communities in Genesis around the example of the development of the concept of syphilis over several centuries.
Fleck was an important innovator in both aspects of the "historical turn" in science studies. Fleck's approach to the history and philosophy of science championed both aspects of the founding ideas of historicized science studies -- the importance of the specific social settings of the scientists, and the cognitive features of scientific work within a community of researchers. He emphasized the importance of the specific social arrangements within which scientific knowledge is produced:
When we look at the formal aspect of scientific activities, we cannot fail to recognize their social structure. We see organized effort of the collective involving a division of labor, cooperation, preparatory work, technical assistance, mutual exchange of ideas, and controversy. Many publications bear the names of collaborating authors. Scientific papers almost invariably indicate both the establishment and its director by name. There are groups and a hierarchy within the scientific community: followers and antagonists. societies and congresses, periodicals, and arrangements for exchange. A well-organized collective harbors a quantity of knowledge far exceeding the capacity of any one individual. (42)
Fleck also emphasized the conceptual dependency or incommensurability that became important in Kuhn's thought. In particular, Fleck offered a highly original idea about the social or "collective" nature of scientific concepts with his idea of a "thought collective" (denkkollektiv). (Thaddeus Trenn, the translator of Genesis and Development, notes that this term is a neologism introduced by Fleck, and it has no natural counterpart in English.) Here is how Fleck defines denkkollektiv:
If we define "thought collective" [denkkollektiv] as a community of persons mutually exchanging ideas or maintaining intellectual interaction, we will find by implication that it also provides the special "carrier" for the historical development of any field of thought, as well as for the given stock o f knowledge and level of culture. This we have designated thought style. The thought collective thus supplies the missing component. (39)
Fleck illustrates the dependence of scientific theory on the specific denkkollektiv with the example of the development of the modern concept of the agent of syphilis:
Siegel also recognized, in his own way, protozoa-like structures as the causative agent of syphilis. If his findings had had the appropriate influence and received a proper measure of publicity throughout the thought collective, the concept of syphilis would be different today. Some syphilis cases according to present-day nomenclature would then perhaps be regarded as related to variola and other diseases caused by inclusion bodies. Some other cases would be considered indicative of a constitutional disease in the strict sense of the term. Following the train of thought characterized by the "carnal scourge" idea, still another, completely different set of concepts concerning infectious disease and disease entities would have arisen. Ultimately we would still have reached a harmonious system of knowledge even along this line, but it would differ radically from the current one. (39)
The point here is important and plausible. Assumptions about biological structures, causation, and disease accreted within one research tradition -- one denkkollektiv -- constituted an extended and growing system of statements, investigative procedures, and research groups as scientific understanding of syphilis developed, and the theories and findings of the science must be interpreted in terms of that system of beliefs and assumptions. But the development of such a system is a highly contingent process, and a different ensemble of assumptions was possible. On that alternative ensemble, the eventual scientific product would have been quite different. This suggests the idea of "brachiation" in evolutionary theory, where the founder finch has one set of properties, and the daughter variants continue to diverge until there is little similarity with the founder or among the daughter sub-species.
The incommensurability to which Fleck refers seems to be of a fairly ordinary kind: if the scientist in the B-denkkollektiv of syphilis science frames his or her thinking in terms of dramatically different ways from scientists in the A-denkkollektiv -- different ways of defining the problem, different views of biological causation, and different assumptions about "causative agents", then their apparently simple statements about the disease will be difficult to inter-translate. This implies that apparently similar statements in A-language and B-language will have significantly different meanings, implications, and avenues of investigation for the two communities. The scientists in the two denkkollektive in the same domain will often talk past each other -- just as Kuhn asserts 25 years later in SSR.
To some extent a close reading of both Kuhn and Fleck serves to de-dramatize the implications of "incommensurability" that each asserts. Neither of these theorists puts forward a radical view of mutual unintelligibility across research communities, or a radical relativism of the findings of science in a particular field of research. Both reject the simple reductionist semantics of positivism (verificationism, instrumentalism) according to which the meaning of a scientific concept can be fully articulated as a set of procedures for verification. But they do not seem to think that conversation with comprehension is impossible between classical physicists and relativity or quantum physicists, or between wave theorists and particle theorists in subatomic physics, or between gradualists and punctuated-equilibrium theorists in evolutionary theory. Substantive disagreements about the domain of investigation and conflicting predictions about outcomes are possible, and that is enough to allow for meaningful scientific discourse to proceed across paradigms or "thought collectives". In this respect both Kuhn and Fleck are less radical than Berger and Luckmann (link), who make a case for an extreme version of conceptual relativism across cultures in The Social Construction of Reality: A Treatise in the Sociology of Knowledge.
(Polish researcher Paweł Jarnicki has written extensively on Fleck and on the relationship between Fleck's ideas and those of Kuhn. His article "On the shoulders of Ludwik Fleck? On the bilingual philosophical legacy of Ludwik Fleck and its Polish, German and English translations" provides a fascinating philological study of the difficulties of translation raised by Fleck's multilingual writings (link).)
(Here is a discussion of "conceptual frameworks" that is relevant to this discussion of incommensurability of scientific concepts and statements (link).)