Issues in the Logic of Reductive Explanations, Ernest Nagel
- the most important distinction:
“Bridge laws state what relations presumably obtain between the extensions of their terms, so that in favorable cases laws of the “narrower” theory (with suitable qualifications about their approximate character) can be deduced from the “wider” theory, and thereby make intelligible why the two theories may have a common field of application.” pg.920.
I do believe reductionism is a natural process when we are dealing with a specific problem. We cannot start to solve the problem of high carbon emission due to combustion products by considering the fundamental particles and the formation of universe, which are the candidates of the widest theories, for example. But, we can specifically yield a theory of molecular interactions including organic compounds and their burning rates with oxygen.
- a clarification question/criticism:
“the meaning of every term occurring in a theory or in its observation statements is wholly and uniquely determined by that theory, so that its meaning is radically changed when the theory is modified. (…) it does not follow that there can be no term in a theory which retains its meaning when it is transplanted into some other theory.” pg.919.
I think Feyerabend has a point to emphasize on changes in meaning. I would like to recall Hilary Putnam’s referential model of meaning, which states 4 parts. And, it is highly possible to lose or change one part during theorizing a phenomenon.
1953 and all That. A Tale of Two Sciences, Philip Kitcher
- the most important distinction:
“It will not simply consist in a chemical derivation adapted with the help of a few. boundary conditions furnished by biology. Instead, we shall encounter a sequence of subarguments: molecular descriptions lead to specifications of cellular properties, from these specifications we draw conclusions about cellular interactions, and from these conclusions we arrive at further molecular descriptions. There is clearly a pattern of reasoning here which involves molecular biology and which extends the explanations furnished by classical genetics by showing how phenotypes depend upon genotypes” pg.367.
This kind of pattern of reasoning can pave the way for bridge theories, too.
- a clarification question/criticism:
“Later theories can be said to provide conceptual refinements of earlier theories when the later theory yields a specification of entities that belong to the extensions of predicates in the language of the earlier theory, with the result that the ways in which the referents of these predicates are fixed are altered in accordance with the new specifications.” pg.363.
Conceptual refinements… Is there a clear distinction between reductions and refinements? I don’t know.