Thomas S. Kuhn 1982.
The term incommensurable is no common measure in this context it becomes no common language, meaning that if two theories are incommensurable, there is no language, neutral or otherwise, into which both theories, conceived as a sets of statements, can be translated without residue or loss, they must be stated in mutually untranslatable languages, if there is no way in which the two can be stated in a single language, then they cannot be compared, and no arguments from evidence can be relevant to the choice between them.
In so far as incommensurability was a claim about language, about meaning change, this form is called local incommensurability. Most of the terms common to two theories function the same way in both; their meanings, whatever those may be, are preserved; their translation is simply homophonic. Only for a small subgroup of (usually interdefined) terms and for sentences containing them do problems of translatability arise. It is simply implausible that some terms should change meaning when transferred to a new theory with out infecting the terms transfered with them. This means that when such an interdefined term (word-sign) is part of two different theories to be compared or translated, these theories are incommensurable.
Some critics sketch the technique of interpretation: describing its outcome as a translation schema; and all conclude that its success is incompatible with even local incommensurability, the matter with this argument is the equation of the interpretation with translation. Kuhn states that interpretation is not the same as translation, the confusion is easy because actual translation often or perhaps always involves at least a small interpretative component
Translation: made by someone who knows two languages, substitution of words(no necessarily one by one).
Interpretation: made by someone who may initially command a single language, what the interpreter makes in a first instance is learn a new language and whether a that language can be translated into the one with which the interpreter began is an open question. Then the interpreter can attempt to describe in English (or the language to be translated into) the referents of the term to translate, if the description is successful, then no issue of incommensurability arises, on the other hand the interpreter may have learned to recognize distinguishing features unknown to English speakers and for which supplies no descriptive terminology, this is the kind of circumstance for which the term incommensurability is reserved.
Two people may speak the same language and nevertheless use different criteria in picking out the referents of its terms, that’s why translation must preserve not only reference but also sense or intension that is the essential role of sets of terms that must be learned together by those raised inside a culture, scientific or other and that, and which foreigners encountering that culture must consider together during interpretation. If different speakers using different criteria succeed in picking out the same referents, for the same terms, contrast sets must have play a role in determining the criteria each associates with individual terms.
The invariants of translation are to be sought , unlike two members of the same language community, speakers of mutually translatable languages need not to share terms, but the referring expressions of one language must be matchable to co referential expressions in the other, and the lexical structures employed by speakers of the language must be the same, not only between each language but also from one language to the other.