This paper argues that conceptualizing unity as “interconnection” (rather than reduction) provides a more fruitful and versatile framework for the philosophical study of scientific unification. Building on the work of Darden and Maull, Kitcher, and Kincaid, I treat unity as a relationship between fields: two fields become more integrated as the number and/or significance of interfield connections grow. Even when reduction fails, two theories or fields can be unified (integrated) in significant ways. I highlight two largely independent dimensions of unification. Fields are theoretically unified to the extent that we understand how the ontologies, concepts, and generalizations of these fields are connected. (Reductionism is one form of theoretical unity, but not the only form). Fields are practically unified through heuristic connections (e.g., using the heuristics of one field to generate hypotheses in another field) and by the development of methods for integrating the qualitatively distinct bodies of data generated by the two fields. I discuss the relationship between paleontological and neontological systematics to illustrate the utility of conceptualizing unity as interconnection.

This paper explains the metaphysical implications of the view that species are individuals (SAI). I first clarify SAI in light of the separate distinctions between individuals and classes, particulars and universals, and abstract and concrete things. I then show why the standard arguments given in defense of SAI are not compelling. Nonetheless, the ontological status of species is linked to the traditional “species problem,” in that certain species concepts do entail that species are individuals. I develop the idea that species names are rigid designators and show how this provides additional motivation for SAI.

This paper argues, first, that recent studies of experimentation, most notably by Deborah Mayo, provide the conceptual resources to describe scientific discovery's early stages as error-probing processes. Second, it shows that this description yields greater understanding of those early stages, including the challenges that they pose, the research strategies associated with them, and their influence on the rest of the discovery process. Throughout, the paper examines the phenomenon of “chemical hormesis” (i.e., anomalous low-dose effects from toxic chemicals) as a case study that is important not only for the biological sciences but also for contemporary public policy. The resulting analysis is significant for at least two reasons. First, by elucidating the importance of discovery's earliest stages, it expands previous accounts by philosophers such as William Wimsatt and Lindley Darden. Second, it identifies the discovery process as yet another philosophical topic on which the detailed studies of the “new experimentalists” can shed new light.

Kim claims that Bechtel and Mundale's case against multiple realization depends on the wrong kind of evidence. The latter argue that neuroscientific practice shows neural states across individuals and species are type identical. Kim replies that the evidence they cite to support this is irrelevant. I defend Bechtel and Mundale by showing why the evidence they cite is relevant and shows multiple realization does not occur.

Myrvold (2003) has proposed an attractive Bayesian account of why theories that unify phenomena tend to derive greater epistemic support from those phenomena than do theories that fail to unify them. It is argued, however, that “unification” in Myrvold's sense is both too easy and too difficult for theories to achieve. Myrvold's account fails to capture what it is that makes unification sometimes count in a theory's favor.