This paper was developed over the course of several years. Drafts were posted on-line beginning Sep 6, 2007. Although I have used parts of it in other work, it has not been published in its entirety. I have prepared a stable unpublished version, which is suitable for citation.
Against the common and often implicit assumption that theories are a singular kind of thing, this paper argues for theory concept pluralism: There are multiple distinct theory concepts which we legitimately use in different domains and for different purposes. The primary argument is an analogy with species concept pluralism. Just as biologists use multiple species concepts, none of which could be used in place of all the others, philosophers are forced to think about theory in multiple ways. I conclude by distinguishing theory concept pluralism from other pluralist positions.
@UNPUBLISHED{Magnus2012,
AUTHOR = {P.D. Magnus},
TITLE = {What SPECIES can teach us about THEORY},
URL = {http://www.fecundity.com/job/papers.php?item=speciesanalogy}
)