In
Structure of Scientific Revolutions, Thomas S. Kuhn introduced the single most striking concept of "paradigm" into the discourse of Philosophy of Science, which people of a set or community shared. Thirty years after, in a paper titled "The Road since Structure", Kuhn seems to make an attempt to go beyond this model by revisiting and exploring the structures behind paradigms themselves. Of course, his central concerns in general are again: rationality, relativism, realism and truth, but most crucially he formulates the idea of
incommensurability as fundamental to the viewing and understanding of scientific knowledge.
Kuhn traces the evolution of incommensurability from the period when there were attempts to understand apparently nonsensical passages in old scientific texts, ordinarily taken to be confused or mistaken beliefs, and therefore taken to be incommensurable. However, it was later realized that this apparent nonsense could be wholly removed by recovering the old meanings that were indeed remarkably different. Metaphorically, Kuhn explained this earlier, as a ‘process’ by which later meanings evolve from earlier ones with changes in language. But to be more specific, Kuhn adds that, in talking about scientific knowledge he is not really dealing with all general features of language as such but with meanings of a certain restricted class of terms. These are "taxonomic terms" or "kind terms" which include count nouns, mass nouns or classes- that take the indefinite article; in other words, the many classificatory systems that underlie scientific knowledge.
The two properties that taxonomic terms or kind terms have are that they (i) take the indefinite article. It would thus be essential to know what the term applies to or its denotation, and (ii) work with the no- overlap principle, a certain ‘boundary definition’; which is to the effect that no two terms with a kind label, unless related as species to genus, can overlap. For example, things as dogs/cats/silver, etc. are all different from each other in kind because there is no overlap in their boundary definition. Kuhn points out that a "… lexical taxonomy of some sort must be in place before description of the world can begin..."(p.233, para 2). It is the shared lexical taxonomy that allows statements to be meaningful in a given discourse. What follows is that there is: (a) a presupposed lexical taxonomy, (b) which is shared (c) for unproblematic and meaningful communication. Community discourse is thus always context specific.
Statements and theories are always situated within a specific taxonomy and they are both developed and validated/or rejected in that scheme. Two examples that Kuhn offers to illustrate his idea are: one, the untranslatability of the English phrase "the cat sat on the mat" into French owing to taxonomical difficulties, (that there really is no French counterpart to the term "mat" in English); and two, the Copernican statement "planets travel around the sun" cannot be expressed in a lexical structure which works with the taxonomy of the Ptolemaic statement "planets travel around the earth" (p.234). Kuhn asserts that lexical taxonomy roughly means a conceptual scheme that is not tied to a ‘set of belief’ but is of a ‘mental module’ , which is the very pre-requisite to having certain beliefs and even being able to conceive them.
Here, Kuhn appears to be accounting for what makes it possible to conceive things in a certain way, perhaps even the pre-linguistic structures and the visual and cognitive configurations that determine the way we see, know and understand. He further claims that violation of the no-overlap principle, etc. leads to incommensurability or untranslatability, "localized to one or another area in which two lexical taxonomies differ". This would mean that experience of world and its communication would necessarily take place within the structure of lexicon of a community. And it is virtually impossible to communicate all experience in its completeness across a lexical divide. When two different sets of taxonomies confront each other, the result is mutual incommensurability or untranslatability.
Kuhn then locates incommensurability within a developmental framework (within which it appears) and subsequently charts the course of an evolutionary epistemology. He admits that in thinking that history functioned as source of empirical evidence, the empirical aspect had been exaggerated. Beliefs are already there, there is a process in progress. The pursuit of science is situated within this process and there was no need of empirical observation of actual practices to conclude this. This clearly undermines the foundationalist description of things. Another serious consequence that follows from the rejection of foundationalism is the dismissal of the correspondence theory of truth. Developmental view traces and evaluates scientific knowledge claims not from an ‘Archimedean platform’ but from a moving historically situated platform. It would be incorrect to evaluate a theory in isolation since theories are dependent and connected. The implication is that any new theory or proposition requires necessarily an adjustment with other beliefs.
Comparative judgments are, then, to do with the question of "which one of two bodies of knowledge is better" for a given work. This would amount really to a pragmatic decision. Such judgments have, as given, shared beliefs as part of the historical situation. Their evaluation would not depend on their being in fact true/false. However, this also implies that the question of truth/falsity of the changes made/ or the rejection of the judgment on those accounts simply does not arise. Justification of a belief does not aim at a goal external to the historical situation, thus, questioning the very basis of correspondence theory. The aim rather is to improve the tools available for the work engaged in.
The distinction between normal development and revolutionary development is what Kuhn draws upon, next. Outlining the parallels of biological evolution with scientific development, in so far as knowledge mutates and analogous speciation (creation of new disciplines, etc.) takes place, Kuhn stresses that in
Structure, normal development was the development that added to existing knowledge while revolutionary development was a radical one that required giving up part of what had been believed before. In his fresh formulation, Kuhn seems to argue that revolutionary development is one that requires taxonomic changes, while normal development would be one that didn’t need any. He also asserts that more cognitive specialties or separate fields of knowledge arise, essentially at zones of lexical overlaps, each field being distinct in having developed a separate lexicon.
Instead of a correspondence theory, Kuhn primarily argues for a redundancy theory of truth. In other words, now the essential function of truth involves choosing between acceptance and rejection of the statement/ theory in question in the face of ‘evidence shared by all’. There is increasing belief for Kuhn that his central points would be better formulated without speaking of statements as themselves being true/false. Instead, he offers an alternative two-fold evaluation to determine the status of any statement:
(i) This would involve asking: ‘Is the statement a possible candidate for truth/falsity?
(ii) If yes, ‘Is the statement rationally assertable?’
The answer to (ii) would be obviously answered by the normal ‘rules of evidence’ given a specific lexicon. Rules of evidence are laid down by the community sharing a lexical taxonomy.
To give an instance, Kuhn points out that the basic principle of non-contradiction is valued in discourses in one language game while there are exceptions to it in certain other language games. The violation of the principle of non-contradiction is well expressed, for instance, in "poetry and metaphysical discourse" and its exploitation is common and justified in use of "metaphors". Rules of truth/falsity game are universal and essentially human, although, the result of applying those rules would differ.
What is stressed is that breakdowns in communication, termed "crises" (
Structure), are in fact crucial symptoms of growth of knowledge and the emergence of new disciplines. Where there is stark untranslatability or incommensurability, there is a new lexical taxonomy in place. This new taxonomy results in a new discipline altogether. Kuhn maintains that the process of specialization imposes limitations on communication and community, making one field of knowledge inaccessible to another community which is unacquainted with that taxonomy. However, this limitation is inevitable owing to the necessary lexical divergence in the evolution of distinct fields. He is further led to argue that though lexical diversity amounts to: (a) a principled limit on communication and (b) a limited range of possible partners for a discourse, this is an essential precondition for any progress in knowledge.
Kuhn is careful to ward off any attempt to conclude the world as being either mind dependent or an invention/construction. There are two reasons that he offers in his defence: one, the world is not invented or constructed because we find the world already there before us, it is ‘given’ to us and two, it is experientially both given directly and indirectly to us. It often goes against our wishes. There are many times, “decisive evidence against invented hypotheses". This is however not to deny that there is always scope for interaction, leading to alteration of both the member and the world it constitutes. The question whether it is the creatures who adapt to the world or the world adapts to creatures" (p.242, para 2) is one that is raised in this context. Kuhn observes, that the ‘world is our representation of our niche’, of a given interacting community. Clearly though, this is meant to counter any subjectivist interpretation.
Even in talking of non overlapping lexical structures Kuhn is concerned with wanting to preserve something permanent, fixed, stable underlying difference and change. However, reiterating, as he puts it at the end, ‘Ways of being-in-the-world which lexicon provides are not candidates for truth or falsity'.
