Jonathan Schaffer

What is the relation between material objects and spacetime regions? Supposing that spacetime regions are one sort of substance, there remains the question of whether or not material objects are a second sort of substance. This is the question of dualistic versus monistic substantivalism. I will defend the monistic view. In particular, I will maintain that material objects should be identified with spacetime regions. There is the spacetime manifold, and the fundamental properties are pinned directly to it

Questions about the metaphysics of causation may be usefully divided as follows. First, there are questions about the nature of the causal relata, including (1.1) whether they are in spacetime immanence), (1.2) how fine grained they are individuation), and (1.3) how many there are adicity). Second, there are questions about the metaphysics of the causal relation, including (2.1) what is the difference between causally related and causally unrelated sequences connection), (2.2) what is the difference between sequences related as cause to effect, and those related as effect to cause or as joint effects of a common cause direction), and (2.3) what is the difference between sequences involving the cause, and those involving mere conditions selection).

Suppose that Ann says, “Keith knows that the bank will be open tomorrow.” Her audience may well agree. Her knowledge ascription may seem true. But now suppose that Ben—in a different context—also says “Keith knows that the bank will be open tomorrow.” His audience may well disagree. His knowledge ascription may seem false. Indeed, a number of philosophers have claimed that people’s intuitions about knowledge ascriptions are context sensitive, in the sense that the very same knowledge ascription can seem true in one conversational context but false in another. This purported fact about people’s intuitions serves as one of the main pieces of evidence for epistemic contextualism.

Knowledge ascriptions are contrast-sensitive. One natural explanation for this is that the knowledge relation is contrastive ( s knows that p rather than q ). But can the binary view of knowledge ( s knows that p ) explain contrast-sensitivity? I review some of the linguistic data supporting contrast-sensitivity, and critique the three main binary explanations for contrast-sensitivity. I conclude that the contrast-sensitivity of knowledge ascriptions shows that knowledge is a contrastive relation

Kaplan (drawing on Montague and Prior, inter alia) made explicit the idea of world and time neutral propositions, which bear truth values only relative to world and time parameters. There was then a debate over the role of time. Temporalists sided with Kaplan in maintaining time neutral propositions with time relative truth values, while eternalists claimed that all propositions specify the needed time information and so bear the same truth value at all times. But there never was much of a parallel debate over the role of worlds. Let contingentism be the view (parallel to temporalism) that sides with Kaplan in maintaining world neutral propositions with world relative truth values, and let necessitarianism be the view (parallel to eternalism) that propositions specify the needed world information and so bear the same truth value at all worlds. This is the story of how the debate between the contingentists and the necessitarians might begin.

Does what you know depend on what is at stake for you? That is, is the knowledge relation sensitive to the subject’s practical interests? Subject sensitive invariantists (Fantl and McGrath, 2002; Hawthorne, 2004, ch. 4; Stanley, forthcoming) say that the answer is yes. They claim to capture the contextualist data without the shifty semantics. I will argue that the answer is no. The knowledge relation is sensitive to what is in question for the attributor, rather than what is at stake for the subject. There is no substitute for the contextualist semantics.

Metaphysical semantics is supposed to connect the nonfundamental to the fundamental in a distinctively “linguistic” way, explaining how nonfundamental truths can be grounded in fundamental facts , and so inducing a radically eliminative vision of the nonfundamental as mere talk. I wonder how the story goes when a single nonfundamental truth can be grounded in many different fundamental facts. For instance, the truth that Moore has hands can presumably be grounded in many different distributions of fields, arrangements of particles, vibrations of strings, or whatnot. I am asking how metaphysical semantics can accommodate this sort of multiple realizability

What knowledge is imperilled by sceptical doubt? That is, what range of beliefs may be called into doubt by sceptical nightmares like the Cartesian demon hypothesis? It is generally thought that demons have limited powers, perhaps only threatening a posteriori knowledge of the external world, but at any rate not threatening principles like the cogito. I will argue that there is a demon – the debasing demon – with unlimited powers, which threatens universal doubt. Rather than deceiving us with falsities, the debasing demon would allow us true beliefs, but only as guesses.

The physical and/or intrinsic connection approach to causation has become prominent in the recent literature, with Salmon, Dowe, Menzies, and Armstrong among its leading proponents. I show that there is a type of causation, causation by disconnection, with no physical or intrinsic connection between cause and effect. Only Hume-style conditions approaches and hybrid conditions-connections approaches appear to be able to handle causation by disconnection. Some Hume-style, extrinsic, absence-relating, necessary and/or sufficient condition component of the causal relation proves to be needed.