This article proposes the use of temporal logic for an analysis of instrumentality inspired by the work of G.H. von Wright. The first part of the article contains the philosophical foundations. We discuss von Wright’s general theory of agency and his account of instrumentality. Moreover, we propose several refinements to this framework via rigorous definitions of the core notions involved. In the second part, we develop a logical system called Temporal Logic of Action and Expectations (TLAE). The logic is inspired (...) by a fragment of propositional dynamic logic based on indeterministic time. The system is proven to be weakly complete relative to its given semantics. We then employ TLAE to formalise and analyse the instrumentality relations defined in the first part of the paper. Last, we point out philosophical implications and possible extensions of our work. (shrink)

I defend the view that a reason for someone to do something is just a reason why she ought to do it. This simple view has been thought incompatible with the existence of reasons to do things that we may refrain from doing or even ought not to do. For it is widely assumed that there are reasons why we ought to do something only if we ought to do it. I present several counterexamples to this principle and reject some (...) ways of understanding "ought" so that the principle is compatible with my examples. I conclude with a hypothesis for when and why the principle should be expected to fail. (shrink)

Some intuitive normative principles raise vexing 'detaching problems' by their failure to license modus ponens. I examine three such principles (a self-reliance principle and two different instrumental principles) and recent stategies employed to resolve their detaching problems. I show that solving these problems necessitates postulating an indefinitely large number of senses for 'ought'. The semantics for 'ought' that is standard in linguistics offers a unifying strategy for solving these problems, but I argue that an alternative approach combining an end-relational theory (...) of normativity with a comparative probabilistic semantics for 'ought' provides a more satisfactory solution. (shrink)

This paper argues that the innovation of an ordering source parameter in the standard Lewis-Kratzer semantics for modals was a mistake, at least for English auxiliaries like ‘ought’, and that a simpler dyadic semantics (as proposed in my earlier work) provides a superior account of normative uses of modals. I programmatically investigate problems arising from (i) instrumental conditionals, (ii) gradability and “weak necessity”, (iii) information-sensitivity, and (iv) conflicts, and show how the simpler semantics provides intuitive solutions given three basic moves: (...) (1) an end-relational analysis of normative modality, (2) a “most” analysis of “weak necessity”, and (3) well-motivated appeals to pragmatics. I conclude with metasemantic observations about the desiderata for a semantics for ‘ought’. (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)