Online research in philosophy

Substitution and simple sentences -- Simple sentences and semantics -- Simple sentences and implicatures -- The enlightenment problem and a common assumption -- Abandoning (EOI) -- Beyond matching propositions -- App. A : extending the account -- App. B : belief reporting.

David’s epistemic understanding of two-dimensional semantics has these two features. First, although he considers at least two construals of epistemically possible worlds, on one of them they are centered metaphysically possible worlds. Second, David intends epistemic two-dimensional semantics to yield a theory of propositional-attitude content, as well as having application to the semantics of natural language expressions. These two features come together in David’s “The Components of Content,” where he deploys the apparatus of epistemic two-dimensional semantics to provide an account of propositional-attitude content, and where, for reasons of simplicity and familiarity, epistemically possible worlds are taken to be centered metaphysically possible worlds. My talk is about this account of content.

Following Lewis, it is widely held that branching worlds differ in important ways from diverging worlds. There is, however, a simple and natural semantics under which ordinary sentences uttered in branching worlds have much the same truth values as they conventionally have in diverging worlds. Under this semantics, whether branching or diverging, speakers cannot say in advance which branch or world is theirs. They are uncertain as to the outcome. This same semantics ensures the truth of utterances typically made about quantum mechanical contingencies, including statements of uncertainty, if the Everett interpretation of quantum mechanics is true. The 'incoherence problem' of the Everett interpretation, that it can give no meaning to the notion of uncertainty, is thereby solved.

Since universal language systems are confronted with serious paradoxical consequences, a semantic approach is developed in whichpartial worlds form the ontological basis. This approach shares withsituation semantics the basic idea that statements always refer to certain partial worlds, and it agrees with the extensional and model-theoretic character ofpossible worlds semantics. Within the framework of the partial worlds conception a satisfactory solution to theLiar paradox can be formulated. In particular, one advantage of this approach over those theories that are based on the totality of possible worlds semantics can be found in the fact that the so-called Strengthened Liar problem is avoided.

This thesis deals with the phenomenon of attitude reporting. More specifically, it provides a unified semantics of de re and de se belief reports. After arguing that de se belief is best thought of as a special case of de re belief, I examine whether we can extend this unification to the realm of belief reports. I show how, despite very promising first steps, previous attempts in this direction ultimately fail with respect to some relatively recent linguistic data involving quantified and infinitival reports, logophoric constructions, and monstrously shifted indexicals. Formalizing my idea of a contextual resolution of acquaintance relations in a dynamic framework, I arrive at an alternative analysis that handles all these data.

Possible worlds semantics has been very useful in modeling not only the intensionality of necessity and possibility, future and past. It has also found its place in modeling the intentionality of propositional attitudes like belief and knowledge. There is something fruitful in analyzing a belief as a set of possible worlds. The belief is the set of possible worlds in which the belief is true. The belief is true if and only if the actual world is in the corresponding set of propositions. The possible worlds in the set corresponding to the belief represent how the agent per- ceives the world to be. If the belief is false, then the world isn’t how the agent sees the world to be, and so the actual world isn’t in the set of worlds corresponding to the belief (see Lewis [4] and Stalnaker [9]). The same can be said of whole belief states just as much as it can be said of individual beliefs. My belief state is the set of worlds consistent with what I believe. This view has been very fruitful, not least because the set-theoretic structure of sets of possible worlds corresponds nicely with the logical structure of entailment relations among propositions and the behavior of propositional connectives like conjunction, disjunction, and negation. However, the story does not deal well with inconsistent belief. Inconsistent beliefs are true in no possible worlds, so they are each modeled by the same set of worlds—the empty set. My beliefs are often inconsistent, and so are those of many..

In this paper it is argued that the conjunction of linguistic ersatzism, the ontologically deflationary view that possible worlds are maximal and consistent sets of sentences, and possible world semantics, the view that the meaning of a sentence is the set of possible worlds at which it is true, implies that no actual speaker can effectively use virtually any language to successfully communicate information. This result is based on complexity issues that relate to our finite computational ability to deal with large bodies of information and a strong, but well motivated, assumption about the cognitive accessibility of meanings of sentences ersatzers seem to be implicitly committed to. It follows that linguistic ersatzism, possible world semantics, or both must be rejected.

Some twenty years ago, semanticists of natural language came to be overwhelmed by the problem of semantic analysis of belief sentences (and sentences reporting other kinds of propositional attitudes): the trouble was that sentences of the shapes X believes that A and X believes that B appeared to be able to have different truth values even in cases when A and B shared the same intension, i.e. were, from the viewpoint of intensional semantics, synonymous 1 . Thus, taking intensional semantics for granted, belief sentences appeared to violate the principle of intersubstitutivity of synonyms. The verdict of the gurus of intensional semantics was that hence intensional semantics is inadequate, or at least insufficient for the purposes of analysis of propositional attitudes; and that we need a kind of a ‘hyperintensional semantics’.

This paper concerns the semantics of belief-sentences. I pass over ontologically lavish theories which appeal to impossible worlds, or other points of reference which contain more than possible worlds. I then refute ontologically stingy, quotational theories. My own theory employs the techniques of possible worlds semantics to elaborate a Fregean analysis of belief-sentences. In a belief-sentence, the embedded clause does not have its usual reference, but refers rather to its own semantic structure. I show how this theory can accommodate quantification into belief-contexts. I close with skirmishes against the threat posed by the Liar Paradox.