A standard illustration' of this situation in this: let M~ be a theory of mechanics employing mass points as basic objects and let Mz be similar yet with only extended objects as its primitive elements. Let M> postulate that mass points come only in dense collections. Granted reasonable assumptions about the further details of Mq and M2, we can define the extended objects of Mz in M~ as dense sets of mass points whereas the latter can be defined in Mz (...) as nested sets of the former. Both theories offer equivalent descriptions of the world in the sense that any claim of Mq can be systematically translated into a theorem of Mz and conversely. (shrink)

If two theory formulations are merely different expressions of the same theory, then any problem of choosing between them cannot be due to the underdetermination of theories by data. So one might suspect that we need to be able to tell distinct theories from mere alternate formulations before we can say anything substantive about underdetermination, that we need to solve the problem of identical rivals before addressing the problem of underdetermination. Here I consider two possible solutions: Quine proposes that we (...) call two theories identical if they are equivalent under a reconstrual of predicates, but this would mishandle important cases. Another proposal is to defer to the particular judgements of actual scientists. Consideration of an historical episodethe alleged equivalence of wave and matrix mechanicsshows that this second proposal also fails. Nevertheless, I suggest, the original suspicion is wrong; there are ways to enquire into underdetermination without having solved the problem of identical rivals. (shrink)

A central tenet of cognitivism is that knowing how is to be explained in terms of tacitly knowing that a theory is true. By critically examining canonical anti-behaviorist arguments and contemporary appeals to tacit knowledge, I have devised a more explicit characterization in which tacitly known theories must act as justifiers for claims that the tacit knower is capable of explicitly endorsing. In this manner the new account is specifically tied to verbal behavior. In addition, if the analysis is correct (...) then it follows that the scope and nature of cognitivist appeals to tacit knowledge are largely mistaken. (shrink)