Cian Dorr

This paper lays out a novel proposal about the metaphysical foundations of (non-relativistic) quantum mechanics, which has some elements in common with Everett's “Many Worlds” interpretation and some elements in common with Bohm's ”Pilot Wave” interpretation. The view agrees with the Everettians that the quantum wavefunction can be interpreted be interpreted as a <em>complete</em> description of the world in fundamental terms. But it holds that this truth of this description suffices for the existence of an <em>uncountable</em> plurality of “worlds” of ordinary, non-fundamental objects, where each such “world” corresponds to a mapping of points of time to points of configuration space that obeys that Bohmian “Guidance Equation”.

Ladyman, Ross and their collaborators (Spurrett is a co-author of two chapters, Collier of one) begin their book with a ferocious attack on "analytic metaphysics", as it is currently practiced. Their opening blast claims that contemporary analytic metaphysics 'contributes nothing to human knowledge': its practitioners are 'wasting their talents', and the whole enterprise, although 'engaged in by some extremely intelligent and morally serious people, fails to qualify as part of the enlightened pursuit of objective truth, and should be discontinued' (vii). They set out on a 'mission of disciplinary rescue' in the spirit of Hume and the logical positivists, in which a fair proportion of philosophy as currently practiced -- as they realize, their critique applies far beyond the boundaries of metaphysics proper -- will be consigned to the flames

In 1950, Quine inaugurated a strange new way of talking about philosophy. The hallmark of this approach is a propensity to take ordinary colloquial sentences that all of us utter routinely when we are not thinking about philosophy, or (more often) other sentences that very directly and obviously logically entail such sentences, and treat those sentences (i) as having a clear content, calling for little or no elucidation, and (ii) as proper objects of philosophical controversy. Questions like ‘are there numbers?’ and ‘are there tables?’ were now placed on a par with questions like ‘are there immaterial souls?’ and ‘are there sense-data?’. Of course philosophers have always had a propensity to say things that sound odd to vulgar ears. What was new with Quine was a systematic policty of privileging these kinds of formulations over more distinctively philosophical idioms. Jargon which had been central to the practice of metaphysics—’logical construction’, ’nothing over and above’, ‘reduce’, ‘ground’, ‘in virtue of’, ‘fundamental’, ‘consist in’...—were shifted to a much more peripheral role. The tradition inaugurated by Quine raises some hard interpretative questions for anyone who, like me and Dave, thinks that there is a range of different propositions that people brought up as English-speakers might be tempted to try to get across by uttering one of these sentences. On the one hand, Dave and I agree that the propositions that any ordinary, unphilosophical use of a sentence like ‘there are some free tables at the back of the café’ would be intended to get across are (in many cases) extremely obvious. The idea that when ontologists assert ‘there are no tables’, or treat this claim as calling for serious debate, they are intending to call into question propositions as obvious as that seems implausibly uncharitable. On the other hand, it is also a hallmark of the Quinean tradition that it claims to be using words in their ordinary sense, at least to the extent that (unlike its founder) it is willing to traffic in talk of meanings at all..

Argument that Q∃ expresses more than one proposition: (1) Q∃ expresses the proposition that Q∃ expresses some proposition that isn’t true. ((E)) (2) If Q ∃ expresses only true propositions, then the proposition that Q ∃ expresses some proposition that isn’t true is true. ((1)) (3) If Q∃ expresses only true propositions, then some proposition expressed by Q∃ is not true. (2, T) (4) Some proposition expressed by Q ∃ is not true. ((3)) (5) The proposition that Q ∃ expresses some proposition that isn’t true is true. (4, T) (6) Q∃ expresses at least one true proposition. (1,5) (7) Q∃ expresses at least two propositions. (3, 6) (A parallel argument shows that Q∀ expresses both true and false propositions

This paper investigates the form a modal realist analysis of possibility and necessity should take. It concludes that according to the best version of modal realism, the notion of a world plays no role in the analysis of modal claims. All contingent claims contain some de re element; the effect of modal operators on these elements is described by a counterpart theory which takes the same form whether the de re reference is to a world or to something else. This fully general counterpart theory can validate orthodox modal logic, including the logic of 'actually'.

Let me regale you with yet another variant of the story of Sleeping Beauty. In this one, the experiment takes place in a room with a skylight, so that Beauty can see what the weather is like outside as soon as she wakes up. The weather can be in any one of n different states on any given day. Beauty regards each of these states as equiprobable; moreover, she takes there to be no correlation between the weather on Monday and the weather on Tuesday, or between the weather on either day and the coin-toss. The rest of the story works as usual: Beauty will be awoken on Monday, after which a coin will be tossed; if it lands Tails, she will be woken again on Tuesday having had her memories of the Monday awakening erased; otherwise, she will stay asleep until Wednesday.1 The weather is the only source of variation in her wakings, so if it should happen that the weather is the same on Monday and Tuesday, her total evidence will be exactly the same on both wakings

I motivate and briefly sketch a linguistic theory of vagueness, on which the notion of indeterminacy is understood in terms of the conventions of language: a sentence is indeterminate iff the conventions of language either forbid asserting it and forbid asserting its negation, under the circumstances, or permit asserting either. I then consider an objection that purports to show that if this theory (or, as far as I can see, any other theory of vagueness that deserved the label "linguistic" were true, there would be no such thing as indeterminacy. I respond to this objection by arguing on independent grounds against its main premise, the widely-accepted claim that if it is indeterminate whether P, no human being knows whether P. I defend an alternative view according to which, when it is indeterminate whether P, it is often also indeterminate whether we know that P.