Commensurability (philosophy of science)
With the incommensurability partial or complete Untranslatability the terms of a scientific theory in the terms of another theory is referred to in the philosophy of science. The term plays a role in the discussion of whether and in what way between ( competing ) theories of a logical relationship can be produced and in what way they can be compared.
The term was introduced in the early 1960 science theory of Thomas Kuhn and Paul Feyerabend. Model was the term used in the mathematics of incommensurability. The specific concepts of incommensurability of Kuhn and Feyerabend, and in particular the conclusions that both draw from the they represent thesis that incommensurability in the history of science plays a role, differ considerably in some respects.
Thomas S. Kuhn
Kuhn has Inkommmensurabiliät first presented in his book The Structure of Scientific Revolutions, where the incommensurability is connected to a paradigm change during scientific revolutions. His notion of incommensurability subject of a development that ultimately led to the basis of his concept of incommensurability Willard Van Orman Quine's thesis of the underdetermination of translations. For Kuhn, there is no global incommensurability of all terms of incommensurable theories, but only locally restricted incommensurability of some terms.
Although Kuhn is no direct " term -to- term " comparison between different incommensurable theories can be made, he also holds incommensurable theories in principle be comparable. Instead of a term -to- term comparison could a comparison about to take place by and independent of the paradigm shared values , such as accuracy, simplicity, internal and external consistency, etc. reception of his work, which comprehend him as a representative of relativism, he disagreed on several occasions:
"Most readers [ ... ] have Supposed did when i spoke of theories as incommensurable, I meant thatthey Could not be Compared. But ' incommensurability ' is a term borrowed from mathematics, and it there has no implication examined. The hypotenuse of an isosceles right triangle is incommensurable with its side, but the two can be Compared To any required degree of precision. "
" Most readers [ ... ] have assumed that when I spoke of theories as incommensurable, I would think that they are not comparable. But ' incommensurability ' is a term borrowed from mathematics expression, and there he has no such implication. The hypotenuse of an isosceles and right triangle is incommensurable with its side, but both can be compared with any degree of accuracy. "
Paul Feyerabend
Compared to Kuhn Feyerabend's conception of incommensurability is more radical. Incommensurable theories are after him, not only locally but globally incommensurable, ie not a primitive notion of a theory can be translated into each other, there is no bridge laws and the principles of konzeptualen apparatuses of both theories are incompatible. A simple logical- rational comparison between incommensurable theories is not possible for Feyerabend. Still not automatically follow for him so incomparability of both theories. Rather, the comparison inkommmensurabler theories may be difficult and not for simple standards - such as suggested by the critical rationalism - possible, comparisons should be but in other respects - among other things, about the criterion of prediction success - possible. In Feyerabend the incommensurability between theories is rather rare. While Kuhn incommensurability is a concomitant of any paradigm shift in scientific revolutions, Inkommensurabiliät is for Feyerabend, for example, not the case with every revolution. The Ptolemaic and the Copernican world view, for example, he sees not as incommensurable. Only so-called universal theories may be incommensurable, provided that they are interpreted in a certain way.
Feyerabend draws from his Inkommensurabilitätshypothese the conclusion that there are no simple universal methods and rules which can ensure rational approach. The rules by which scientists work, but are complex and contextual. It represents therefore an anarchist epistemology and social democratic relativism. For Feyerabend is performing such a way to arrange the Company, an increase of rationality:
"There is no need to fear did search a way of arranging society will lead to undesireable results. Science Itself uses the method of ballot, discussion, vote, though without a clear grasp of its mechanism, and in a heavily biased way. But the rationality of our beliefs Will certainly be Increased Considerably. "
" There is no reason to fear that as a way to arrange the society will lead to undesirable results. Science itself uses the methods of surveys, discussions and votes without having a clear understanding of their mechanisms, and in a highly biased manner. But the rationality of our beliefs is sure to be greatly increased. "
Hans Albert
After Hans Albert result of epistemological positions as they developed Kuhn and Feyerabend, an immunization against criticism of individual theories, which he considers methodologically unacceptable.
Inkohärenzargument
The Inkohärenzargument is an objection to the practical relevance of incommensurability. It is not against incommensurability as a theoretical possibility in itself, but against and placed by Kuhn and Feyerabend historical examples that those want to show that incommensurability is not only a more or less exotic theoretical possibility with no relevance to the real existing science, but is practically relevant. It says, in essence, that it is inconsistent to say, earlier worldviews are incommensurable to the present and thus can not be expressed in the language of today, but at the same time to assert that one can analyze them and determine their incommensurability. Pre- Bracht was the argument in different versions, for example, by Hilary Putnam and Donald Davidson. So Putnam criticizes the argument put forward by Feyerabend Galileo example:
" To tell us that Galileo ' incommensurable ' expressions had, and then proceed to describe these in detail, is completely incoherent. "
This inconsistency can be avoided by Howard Sankey by both theories are considered embedded in a meta-language and can be described with this, without using the terms of a theory are directly translatable into other respectively the. Then the theories, although incommensurable, but also rationally comparable.
Incommensurability and rational comparability
In many receptions incommensurability is erroneously equated with incomparability of two theories. Neither Kuhn nor Feyerabend have made such a strict equation.
Even the weaker assumption that the incommensurability, if not necessary then it could possibly be associated in some cases with incomparability is criticized from different sides. Applying is that both Kuhn and Feyerabend their respective justifications for incommensurability put some conditions to reason, which need not necessarily be accepted and for which there are alternatives. Among other things, the concerns about the theory of meaning or the point of view assumed by logical empiricism, which conceives empirical theories as pure sets of statements. Alternative ways to terms assign a meaning to a scientific theory, which also claimed in theory change and scientific revolutions permit a rational comparison, are, for example, the causal theory of meaning, which was represented by Hilary Putnam, or even on the semantic theory conception based views, where theory tapes theory and networks play a role in the way terms are given their meaning.