Commensurability (philosophy of science)

Commensurability is a concept in the philosophy of science whereby scientific theories are commensurable if scientists can discuss them using a shared nomenclature that allows direct comparison of theories to determine which theory is more valid or useful. On the other hand, theories are incommensurable if they are embedded in starkly contrasting conceptual frameworks whose languages do not overlap sufficiently to permit scientists to directly compare the theories or to cite empirical evidence favoring one theory over the other. Discussed by Ludwik Fleck in the 1930s, and popularized by Thomas Kuhn in the 1960s, the problem of incommensurability results in scientists talking past each other, as it were, while comparison of theories is muddled by confusions about terms, contexts and consequences.It is certain, of course, that the relativist scheme has very often given us numbers that are practically identical to the numbers obtained from CM, but this does not mean that the concepts are very similar... even if ...yielding strictly identical predictions can be used as an argument to show that the concepts must match, at least in this case, different magnitudes based on different concepts can give identical values for their respective scales while being different magnitudes... it is not possible to make a comparison of the contents, nor is it possible to make a judgement regarding its verisimilitude.No, because each individual event is rational in the sense that some of its features can be explained by reasons that are or were accepted at the time in which they occurred, or that were invented in the course of their development. Yes, because even these local reasons, which change over time, are not sufficient to explain all the important features of a particular event.Even the most puritanical rationalist will be forced to stop arguing and use propaganda, for example, not because some of their arguments have become invalid, but because the psychological conditions have disappeared that allowed effective argument and therefore influence over the othersThe phrase 'without common measure' is converted into 'without common language'. To state that two theories are incommensurable means that there is no neutral language, or other type of language, into which both theories, conceived as sets of statements, can be translated without remainder or loss... the majority of the terms shared by the two theories function in the same way in both...The terms that retain their meanings following a change in theory provide a suitable base for the discussion of the differences and for the comparisons that are relevant in the selection of theories. It may be noted that these terms are not independent of the theory, but they are simply used in the same way in the two theories in question. It follows that the comparison is a process that compares the two theories, it is not a process that can evaluate the theories separately. Commensurability is a concept in the philosophy of science whereby scientific theories are commensurable if scientists can discuss them using a shared nomenclature that allows direct comparison of theories to determine which theory is more valid or useful. On the other hand, theories are incommensurable if they are embedded in starkly contrasting conceptual frameworks whose languages do not overlap sufficiently to permit scientists to directly compare the theories or to cite empirical evidence favoring one theory over the other. Discussed by Ludwik Fleck in the 1930s, and popularized by Thomas Kuhn in the 1960s, the problem of incommensurability results in scientists talking past each other, as it were, while comparison of theories is muddled by confusions about terms, contexts and consequences. In 1962, Thomas Kuhn and Paul Feyerabend both independently introduced the idea of incommensurability to the philosophy of science. In both cases, the concept came from mathematics; in its original sense, it is defined as the absence of a common unit of measurement that would allow a direct and exact measurement of two variables, such as the prediction of the diagonal of a square from the relationship of its sides. The term commensurability was coined because of a series of problems that both authors found when trying to interpret successive scientific theories. Its implementation is better understood thanks to the critiques that both Kuhn and Feyerabend have made in response to certain theses proposed by followers of the received view of theories. These include the famous thesis on the accumulation of scientific knowledge, which states that the body of scientific knowledge has been increasing with the passage of time. Both Kuhn and Feyerabend reject this thesis, in favor of a model that sees both revolutions and periods of normalcy in the history of science. Another equally important thesis proposes the existence of a neutral language of comparison which can be used to formulate the empirical consequences of two competing theories. This would allow one to choose the theory with the greatest empirically verified contents or explanatory powers—or the greatest content that is not falsified if the formulation is Popperian. The idea at the root of this second thesis does not just relate to the existence of said language but also implies at least two further postulates. Firstly, this choice between theories presupposes that they can be intertranslated, for example between theory A and its successor B – and in the case of Popper that B can be deduced from A. Secondly, it is assumed that the choice is always carried out under the same standards of rationality.