P. D. Magnus

The accepted narrative treats John Stuart Mill's Kinds as the historical prototype for our natural kinds, but Mill actually employs two separate notions: Kinds and natural groups. Considering these, along with the accounts of Mill's 19th-century interlocutors, forces us to recognize two distinct questions. First, what marks a natural kind as worthy of inclusion in taxonomy? Second, what exists in the world that makes a category meet that criterion? Mill's two notions offer separate answers to the two questions: natural groups for taxonomy, and Kinds for ontology. This distinction is ignored in many contemporary debates about natural kinds and is obscured by the standard narrative which treats our natural kinds just as a development of Mill's Kinds.

The underdetermination of theory by evidence is supposed to be a reason to rethink science. It is not. Many authors claim that underdetermination has momentous consequences for the status of scientific claims, but such claims are hidden in an umbra of obscurity and a penumbra of equivocation. So many various phenomena pass for `underdetermination' that it's tempting to think that it is no unified phenomenon at all, so I begin by providing a framework within which all these worries can be seen as species of one genus: A claim of underdetermination involves (at least implicitly) a set of rival theories, a standard of responsible judgment, and a scope of circumstances in which responsible choice between the rivals is impossible. Within this framework, I show that one variety of underdetermination motivated modern scepticism and thus is a familiar problem at the heart of epistemology. I survey arguments that infer from underdetermination to some reëvaluation of science: top-down arguments infer a priori from the ubiquity of underdetermination to some conclusion about science; bottom-up arguments infer from specific instances of underdetermination, to the claim that underdetermination is widespread, and then to some conclusion about science. The top-down arguments either fail to deliver underdetermination of any great significance or (as with modern scepticism) deliver some well-worn epistemic concern. The bottom-up arguments must rely on cases. I consider several promising cases and find them to either be so specialized that they cannot underwrite conclusions about science in general or not be underdetermined at all. Neither top-down nor bottom-up arguments can motivate any deep reconsideration of science.

There are two ways that we might respond to the underdetermination of theory by data. One response, which we can call the agnostic response, is to suspend judgment: "Where scientific standards cannot guide us, we should believe nothing". Another response, which we can call the fideist response, is to believe whatever we would like to believe: "If science cannot speak to the question, then we may believe anything without science ever contradicting us". C.S. Peirce recognized these options and suggested evading the dilemma. It is a Logical Maxim, he suggests, that there could be no genuine underdetermination. This is no longer a viable option in the wake of developments in modern physics, so we must face the dilemma head on. The agnostic and fideist responses to underdetermination represent fundamentally different epistemic viewpoints. Nevertheless, the choice between them is not an unresolvable struggle between incommensurable worldviews. There are legitimate considerations tugging in each direction. Given the balance of these considerations, there should be a modest presumption of agnosticism. This may conflict with Peirce's Logical Maxim, but it preserves all that we can preserve of the Peircean motivation.

The underdetermination of theory by data obtains when, inescapably, evidence is insufficient to allow scientists to decide responsibly between rival theories. One response to would-be underdetermination is to deny that the rival theories are distinct theories at all, insisting instead that they are just different formulations of the same underlying theory; we call this the identical rivals response. An argument adapted from John Norton suggests that the response is presumptively always appropriate, while another from Larry Laudan and Jarrett Leplin suggests that the response is never appropriate. Arguments from Einstein for the special and general theories of relativity may fruitfully be seen as instances of the identical rivals response; since Einstein’s arguments are generally accepted, the response is at least sometimes appropriate. But when is it appropriate? We attempt to steer a middle course between Norton’s view and that of Laudan and Leplin: the identical rivals response is appropriate when there is good reason for adopting a parsimonious ontology. Although in simple cases the identical rivals response need not involve any ontological difference between the theories, in actual scientific cases it typically requires treating apparent posits of the various theories as mere verbal ornaments or computational conveniences. Since these would-be posits are not now detectable, there is no perfectly reliable way to decide whether we should eliminate them or not. As such, there is no rule for deciding whether the identical rivals response is appropriate or not. Nevertheless, there are considerations that suggest for and against the response; we conclude by suggesting two of them

Typical discussions of virtual reality (VR) fixate on technology for providing sensory stimulation of a certain kind. They thus fail to understand reality as the place wherein we live and work, misunderstanding it instead as merely a sort of presentation. The first half of the paper examines popular conceptions of VR. The most common conception is a shallow one according to which VR is a matter of simulating appearances. Yet there is, even in popular depictions, a second, more subtle conception according to which VR is a matter of facilitating new kinds of interaction. The latter half of the paper turns to questions about the contemporary technology of Internet chatrooms. The fact that chatrooms can be used in certain ways suggests something about the prospects for VR. The penultimate section asks whether chatrooms may legitimately be thought of as places. (In a sense, they may.) The final section asks whether cybersex may legitimately be thought of as sex. (Again, yes.) Chatroom technology thus provides an argument for the second conception of VR over its much ballyhooed rival.

Introduction 1 P. D. Magnus and Jacob Busch 1. Form-driven vs. Content-driven Arguments for Realism 8 Juha Saatsi 2. Optimism about the Pessimistic Induction 29 Sherrilyn Roush 3. Metaphysics between the Sciences and Philosophies of Science 59 Anjan Chakravartty 4. Nominalism and Inductive Generalizations 78 Jessica Pfeifer 5. Models and Scientific Representations 94 Otávio Bueno 6. The Identical Rivals Response to Underdetermination 112 Gregory Frost-Arnold and P. D. Magnus 7. Scientific Representation and the Semiotics of Pictures 131 Laura Perini 8. Philosophy of the Environmental Sciences 155 Jay Odenbaugh 9. Value Judgements and the Estimation of Uncertainty in Climate Modeling 172 Justin Biddle and Eric Winsberg 10. Feminist Standpoint Empiricism: Rethinking the Terrain in Feminist Philosophy of Science 198 Kristen Intemann 11. Naturalism and the Enlightenment Ideal: Rethinking a Central Debate in the Philosophy of Social Science 226 Daniel Steel 12. New Approaches to the Division of Cognitive Labor 250 Michael Weisberg.