This paper presents a new theory of the truth conditions for indicative conditionals. The theory allows us to give a fairly unified account of the semantics for indicative and subjunctive conditionals, though there remains a distinction between the two classes. Put simply, the idea behind the theory is that the distinction between the indicative and the subjunctive parallels the distinction between the necessary and the a priori. Since that distinction is best understood formally using the resources of two-dimensional modal logic, (...) those resources will be brought to bear on the logic of conditionals. (shrink)

Many philosophical theories make comparisons between objects, events, states of affairs, worlds, or systems, and many such theories deliver plausible verdicts only if some of the elements they compare are ranked as ‘best.’ When the relevant ordering does not have such ‘best’ or ‘tied for best’ elements the theory wrongly falls silent or gives badly counterintuitive results. This paper develops ordering supervaluationism---a very general technique that allows any such theory to handle these problematic cases. Just as ordinary supervaluation helps us (...) save and generalize ‘uniqueness assuming’ theories, ordering supervaluationism helps us save and generalize ‘limit assuming’ theories. With so many otherwise attractive limit assuming theories, this is a sensible, methodologically conservative approach. (shrink)

Counterfactuals is David Lewis' forceful presentation of and sustained argument for a particular view about propositions which express contrary to fact conditionals, including his famous defense of realism about possible worlds and his theory of laws of nature.

Lemmon argues that dilemmas occur between classes of 'oughts;' duties, obligations, and moral principles. He claims that there are not conflicts within each class, presumably because he is a utilitarian, and thinks that moral principles will always be univocal.

In this paper I offer an account of the meaning of must and can within the framework of possible worlds semantics. The paper consists of two parts: the first argues for a relative concept of modality underlying modal words like must and can in natural language. I give preliminary definitions of the meaning of these words which are formulated in terms of logical consequence and compatibility, respectively. The second part discusses one kind of insufficiency in the meaning definitions given in (...) the first part, which arise from the ex falso quodlibet paradox of logical consequence. In stepwise fashion, I make an attempt to avoid most of the consequences of this paradox for the meaning definitions of must and can. (shrink)

We consider a paradox involving indicative conditionals (‘ifs’) and deontic modals (‘oughts’). After considering and rejecting several standard options for resolv- ing the paradox—including rejecting various premises, positing an ambiguity or hidden contextual sensitivity, and positing a non-obvious logical form—we offer a semantics for deontic modals and indicative conditionals that resolves the paradox by making modus ponens invalid. We argue that this is a result to be welcomed on independent grounds, and we show that rejecting the general validity of modus (...) ponens is compatible with vindicating most ordinary uses of modus ponens in reasoning. (shrink)

I argue that most counterfactuals are false.

The object of our investigation is expressing necessary conditions in natural language, particularly in a certain kind of conditional sentences, the so-called Anankastic Conditionals 2, a topic brought into the linguistic discussion by the seminal papers and. A typical AC is the following sentence, Sæbø’s standard example: If you want to go to Harlem, you have to take the A train. Sæbø analyses the sentence by means of the modal theory in, according to which a modal has two contextual parameters, (...) a modal base f and an ordering source g. The modal base contains relevant facts and the ordering source contains an ideal like wishes, moral laws and the like. Normally, the antecedent of a necessity-conditional is added to the modal base. Sæbø’s new proposal for the analysis of the AC is that the antecedent without the information ‘you want’, called inner antecedent, is added to the ordering source. (shrink)

1 This paper has been presented at the workshop “Time and Modality: A Round Table on Tense, Mood, and Modality”, Paris, December 2005, at a CUNY linguistics colloquium in May 2006, and at the 6th Workshop on Formal Linguistics in Florian´opolis, Brazil, August 2006. We thank the audiences at those presentations, in particular Orin Percus, Tim Stowell, Marcel den Dikken, Anna Szabolcsi, Chris Warnasch, Roberta Pires de Oliveira, Renato Miguel Basso, and Ana M¨uller. We thank Noam Chomsky, Cleo Condoravdi, and (...) Irene Heim for very helpful conversations about this material. We thank Bridget Copley for sharing with us her recent manuscript “What Should Should.. (shrink)

At first glance, this is an entirely unremarkable kind of sentence. It is easy to find naturally occuring exponents. Its meaning is also clear: taking the A train is a necessary condition for going to Harlem. Hence the term “anankastic conditional”, Ananke being the Greek protogonos of inevitability, compulsion and necessity.