In this thesis, I develop a nonreductive and general conception of potentiality, and explore the prospects of a realist account of possibility based on this account of potentiality. Potentialities are properties of individual objects; they include dispositions such as fragility and abilities such as the ability to play the piano. Potentialities are individuated by their manifestation alone. In order to provide a unified account of potentialities, I argue in chapter 2 that dispositions, contrary to philosophical orthodoxy, are best understood in (...) terms only of their manifestations (as disposi- tions to ...), rather than in terms of a stimulus and a manifestation condition (as dispositions to ... if ...). Chapter 3 provides some preliminary motivation for a nonreductive and gen- eral account of potentiality, and chapter 4 develops such an account. The guiding question is how far the notion of potentiality can be extended from the initial ex- amples of familiar dispositions and abilities, and it is argued that it can be extended very far. Various features of potentialities are explored, among them extrinsicality, iterations of potentiality, and the behaviour of potentiality with regard to logical equivalence. In chapter 5, the account is set to work in providing the outlines and a defense of a potentiality-based account of possibility. The basic idea of such an account is that it is possible that p just in case some thing has a potentiality for p. The account is defended against the objection that there may not be enough potential- ities to ground all the possibilities that there are. Finally, in chapter 6, a logic of potentiality is formulated and the logic of possibility derived from it, showing that the potentiality-based account of possibility is formally adequate: it provides pos- sibility with the formal features that modal logicians have studied. I conclude that the proposed account of possibility is a promising research programme. (shrink)

From an indeterminist's perspective, I support and defined the following argument for deontic incompatibilism: If determinism is true, then no one ever can do otherwise than he does. If no one ever can do otherwise than he does, then nothing anyone does is ever right, wrong, or obligatory. Therefore, if determinism is true, then nothing anyone does is ever right, wrong, or obligatory. ;They sense of 'can' I use in this argument is what I call "the power-'can' of ordinary language." (...) The power-'can' has two time indexes; one applies to the power itself, the other to the relevant doing. I argue that the power-'can' is a sense of 'can' with which the "ought implies can" principle holds true. ;I review and respond to various accounts of 'can' proposed by compatibilists Bruce Aune, Keith Lehrer, David Lewis, G. E. Moore and others. Elsewhere I discuss writings by Peter van Inwagen and J. L. Austin. ;To support , I utilize, argue for, and show the advantages of the Temporal Physical Possibility Requirements: If an agent, S, can at time T do A at time T$\sp\prime$, then S's doing A at $T\sp\prime$ is jointly possible with the conjunction of the state of the world at T and the laws of nature. When arguing for these requirements, I focus on how most people use the power-'can' and how they would use it in various situations. I present and respond to objections to my arguments. Most of the objections are based on certain strong forms of contextualism. ;I argue for and defend my premises against various objections. One objection is based on a form of utilitarianism advocated by Fred Feldman. Other objections are based on an example by Harry Frankfurt concerning moral responsibility. ;Two arguments against are presented and I respond. They are developed from a suggestion by John Martin Fischer that people would continue making deontic claims if a consortium of scientists were to find strong evidence of determinism. (shrink)

We propose a new analysis of ability modals. After briefly criticizing extant approaches, we turn our attention to the venerable but vexed conditional analysis of ability ascriptions. We give an account that builds on the conditional analysis, but avoids its weaknesses by incorporating a layer of quantification over a contextually supplied set of actions.

Within philosophy, the word “possible” is generally used to speak about either of the following. (1) Possibility: the notion that is expressed by sentences such as “It is possible that there are green cats,” “She may become the best surgeon in the city,” and “Our team can win the race.” Among the features of possibility, three are of particular interest to philosophers: it is closely related with necessity, contingency, and actuality; it is not unified, but comes in multiple varieties; it (...) is intuitively linked to conceivability. (2) The possible: the target of sentences expressing a possibility, i.e., whatever is possible. Philosophical inquiry is notably interested in the existence and the nature of possible things. For those who think possible things exist, the challenge is to say how and where. For those who think possible things do not exist, the challenge is to say how sentences stating a possibility can be true. (shrink)