Stephen Yablo

Essentialists hold that certain of a thing's properties are specially fundamental, antiessentialists that all of a thing's properties are on a par. As a result, essentialists can explain how, e.g., a statue and its clay are different, but not how they are the same, whereas antiessentialists can explain how they're the same but not how they're different. Ordinarily, though, we reckon them in one sense the same and in another different. ;To accomodate the ordinary view, essentialism and antiessentialism must be brought together. To this end, I identify a property as categorical if its possession in a world speaks to what goes on in that world alone; count essentialist particulars contingently identical in a world if they share their categorical properties there; and introduce antiessentialist, or concrete, particulars as entities for which contingent identity is all the identity there is. Concrete particulars emerge as limiting cases of the essentialist particulars with which they were formerly contrasted, and essentialism and antiessentialism are to that extent reconciled. ;With matters so complicated clarity is at a premium, so the scheme is formalized. Each Kripke model of quantified modal logic is supplemented with a set of properties, constrained so that essences drawn from the set specify what a thing must be like to be the thing it is. When one thing's essence includes another's, they are variants. Properties insensitive to the difference between variants are categorical, and contingent identity is sameness of categorical properties. If concrete things are things existing in one world only, then all their properties are on a par, and they're contingently identical iff properly identical. To show the tractability of reasoning about particulars thus understood, I give a sound and complete logic. ;Formalism isn't an end in itself, but the present formalism pays its way by bringing new clarity to traditional issues: I prove that indiscernibles are identical; give an analysis of kind properties; establish the relativity of cross-world identity between concrete things to kinds; forge new links between modality, time, and potentiality; and give an improved counterfactual account of causation

Kripke, argued like this: it seems possible that E; the appearance can't be explained away as really pertaining to a "presentation" of E; so, pending a different explanation, it is possible that E. Textbook Kripkeans see in the contrast between E and its presentation intimations of a quite general distinction between two sorts of meaning. E's secondary or a posteriori meaning is the set of all worlds w which E, as employed here, truly describes. Its primary or a priori meaning is the set of all w such that if w is actual, then E is true. "Conceivability error" occurs when a primary possibility is mistaken for a secondary one. Textbook Kripkeanism is rejected on the grounds that it makes meaning too modal and modality too much a matter of meaning.

Mental causes are threatened from two directions: from below, since they would appear to be screened off by lower-order, e.g., neural states; and from within, since they would also appear to be screened off by intrinsic, e.g., syntactical states. A principle needed to parry the first threat -causes should be proportional to their effects- appears to leave us open to the second; for why should unneeded extrinsic detail be any less offensive to proportionality than excess microstructure? I say that the second threat relies on a perversion of proportionality that would lay waste to all causal relations.

A lightning fast summary of Yablo, Aboutness, cutting many corners in the interests of brevity. The emphasis is on “ways.” Substituting “ways for S to be true” in for “worlds in which S is true” improves a number of philosophical explanations. The subject matter of S is identified with S’s ways of holding in a world, or failing, as the case may be. S contains T iff T is implied by S, and T’s ways of being true are implied by ways for S to be true ; this kind of way-implication is the same as subject matter inclusion. S’s surplus content over T is explained as that portion of the content of S that is not about whether T. Subject matter is cast throughout as a full partner in meaning.

Aboutness has been studied from any number of angles. Brentano made it the defining feature of the mental. Phenomenologists try to pin down the aboutness-features of particular mental states. Materialists sometimes claim to have grounded aboutness in natural regularities. Attempts have even been made, in library science and information theory, to operationalize the notion. But it has played no real role in philosophical semantics. This is surprising; sentences have aboutness-properties if anything does. Aboutness is the first book to examine through a philosophical lens the role of subject matter in meaning. A long-standing tradition sees meaning as truth-conditions, to be specified by listing the scenarios in which a sentence is true. Nothing is said about the principle of selection--about what in a scenario gets it onto the list. Subject matter is the missing link here. A sentence is true because of how matters stand where its subject matter is concerned. Stephen Yablo maintains that this is not just a feature of subject matter, but its essence. One indicates what a sentence is about by mapping out logical space according to its changing ways of being true or false. The notion of content that results--directed content--is brought to bear on a range of philosophical topics, including ontology, verisimilitude, knowledge, loose talk, assertive content, and philosophical methodology. Written by one of today's leading philosophers, Aboutness represents a major advance in semantics and the philosophy of language.