Approximate Truth and Descriptive Nesting

There is good reason to suppose that our best physical theories, quantum mechanics and special relativity, are false if taken together and literally. If they are in fact false, then how should they count as providing knowledge of the physical world? One might imagine that, while strictly false, our best physical theories are nevertheless in some sense probably approximately true. This paper presents a notion of local probable approximate truth in terms of descriptive nesting relations between current and subsequent theories. This notion helps explain how false physical theories might nevertheless provide physical knowledge of a variety that is particularly salient to diachronic empirical inquiry. 1 Description, Error, and Approximate Truth It is customary to imagine that our best physical theories are true, probably true, or probably approximately true. This view of the proper cognitive status of our best physical theories is well-expressed by Isaac Newton in Rule IV of his Rules for the Study of Natural Philosophy: In experimental philosophy, propositions gathered from phenomena by induction should be considered exactly or very nearly true not withstanding any contrary hypothesis, until yet other phenomena make such propositions either more exact or liable to exceptions. (Newton 1999, 796) J. A. Barrett (&) Department of Logic and Philosophy of Science, School of Social Sciences, University of California at Irvine, Irvine, CA 92697-4555, USA e-mail: [email protected] 1 Hillary Putnam echoes this sentiment in his characterization of scientific realism: when a realistically minded scientist accepts a theory ‘‘he accepts it as true (or probably true, or approximately-true, or probably approximately-true)’’ (Putnam 1979, 210). 123 Erkenn (2008) 68:213–224 DOI 10.1007/s10670-007-9086-6