I was dreaming about Delores when the phone interrupted us. It was the Chief, or ‘Stress,’ as we liked to call him, telling me to get part of my anatomy down to Shakey’s Funeral Parlor. My head ached. I thought I must be the only sucker who gets a hangover from being drunk on life. I got up, put two eggs, a spoonful of wheatgerm, the remains of the scotch, and the phonebill into the blender and fed the whole lot to the cat. It helped, but not as much as Delores would have. I should have married her even if she was a Hubot. At least she could play chess. I was still Rumanating over Delores as I hit the curb outside Shakey’s.

I had the notion that Shakey’s was once a pizza joint but I could have been wrong. I found Stress, disheveled as usual, in the lobby.

‘You’re late,’ he said. I wasn’t, but he’s thatkinda guy. He says ‘Jump!’ and you say ‘With or without my legs?’ We got our free Cokes from Shakey himself, who led us down the hall.

According to Church’s thesis, we can identify the intuitive concept of effective computability with such well-defined mathematical concepts as Turing computability and partial recursiveness. The almost universal acceptance of Church’s thesis among logicians and computer scientists is puzzling from some epistemological perspectives, since no formal proof is possible of a thesis that involves an informal concept such as effectiveness. Elliott Mendelson has recently argued, however, that equivalencies between intuitive notions and precise notions need not always be considered unprovable theses, and that Church’s thesis should be accepted as true.

I want to discuss a thesis that is nearly as important in current research in computer science as Church’s thesis. I call the newer thesis the tractability thesis, since it identifies the intuitive class of computationally tractable problems with a precise class of problems whose solutions can be computed in polynomial time. After briefly reviewing the theory of intractability, I compare the grounds for accepting the tractability thesis with the grounds for accepting Church's thesis. Intimately connected with the tractability thesis is the mathematical conjecture, whose meaning I shall shortly explain, that P≠NP. Unlike Church's thesis, this conjecture is precise enough to be capable of mathematical proof, but most computer scientists believe it even though no proof has been found. As we shall see below, understanding the grounds for acceptance of the conjecture that P≠NP has implications for general questions in the philosophy of mathematics and science, especially concerning the epistemological importance of explanatory and conceptual coherence.

In the Metaphysics, Aristotle pointed out that some activities are engaged in for their own sake, while others are directed at some end. The test for distinguishing between them is to ask, ‘At any time during a period in which someone is Xing, is it also true that they have Xed?’ If both are true, the activity is being done for its own sake. If not, it is being done for the sake of some end other than itself. For example, if I am thinking, it is true that I have thought. But if I’m making a blouse, it is not true that I have made a blouse, at least not this particular blouse. That’s not true until I have completed the project.

There have been a number of attempts to deepen our understanding of this distinction. Anthony Kenny devoted a chapter of Action, Emotion, and Will to this issue, exploring the effect tense has on implication relations, and using that as a basis for dividing verbs of action into state-verbs, activity-verbs and performance-verbs. In more recent years the trend has been to generalize these categories so as to include occurrences other than actions, i.e., occurrences which do not involve intentions. While interest in this area tends to focus primarily on linguistic issues, such as the categorization of verbs, or on the logical analysis of sentences, there has been some interest in related metaphysical issues. In 1978 Alexander Mourelatos published ‘Events, Processes, and States,’ a paper which has turned out to be quite influential, in which he proposes an ontological trichotomy of occurrences. In his view, processes and events form distinct categories within the general category of occurrences. In this paper I will examine the reasoning underlying Mourelatos’s claim, arguing that the differences between processes and events cannot provide the basis for an ontological subcategorization of occurrences.

I am grateful to the editors of the Canadian Journal of Philosophy for inviting me to write a comment on Kathleen Gill’s ‘On the Metaphysical Distinction Between Processes and Events’ (above, 365-84). I readily concede that she is right in the central criticism she makes of my 1978 paper: that a properly metaphysical or ontological distinction between processes and events, if it is to be made at all, cannot be sustained on the basis of the informal linguistic criteria I offered in ‘Events, Processes, and States.’ My main concern in that paper was to show that discussions (back then) of the Kenny-Vendler typology of activities, performances (i.e., accomplishments and achievements, taken together), and states had focused too narrowly on verb types, on adverbial phrases, on the domain of human action, and on English-language intuitions. Mine was one of several voices urging in the late 1970s that issues of tense logic and of the logic of verb types had to be placed in the broader context of verb aspect — a salient and pervasive structure in natural languages generally, and one that had been studied by philologists and linguists since the nineteenth century. Captivated, as I and others had become at the time, by evidence that the distinction between count nouns and mass nouns appears to be mirrored in verb predications, I went on to make some rather venturesome ‘ontological’ claims. It is satisfying, of course, that Gill accepts not only that there is ‘substantial evidence in favor of recognizing a grammatical distinction between the language of processes and [the language of] events’ (369) but also that ‘similarities with count and mass expressions will allow us to apply techniques for han dling nominal expressions to verbal expressions’ (368). It is more than satisfying that the phenomenon of verb aspect is now noticed and investigated by philosophers as well as by linguists.

According to the well-known Kripke-Putnam view developed in Naming and Necessity and ‘The Meaning of Meaning’, proper names and ‘natural kind terms’ - words for natural substances, species, and phenomena (‘water’, ‘rose’, ‘light’) - are non-descriptional and rigid. A singular term is rigid if it has the same referent in every possible world (and with respect to other extension-determining parameters, such as the passage of time), and is non-descriptional if, roughly speaking, its referent (at a possible world or other parameter) is not secured by purely descriptive conditions analytically tied to the term. Thus, ‘the inventor of bifocals’ is nonrigid and descriptional, while ‘the unique even and prime integer’ is rigid and descriptional, and ‘Noam Chomsky’ is rigid and non-descriptional.

In recent years, virtue epistemology has won the attention of a wide range of philosophers. A developed form of the position has been expounded forcefully by Ernest Sosa and represents the most plausible version of reliabilism to date. Through the person of Alvin Plantinga, virtue epistemology has taken philosophy of religion by storm, evoking objections and defenses in a wide variety of journals and volumes. Historically, virtue epistemology has its roots in the work of Thomas Reid, and the explosion of Reid scholarship in the last few years is perhaps both a cause and an effect of recent interest in the position.

In this paper I want to examine the virtues and vices of virtue epistemology. My conclusion will be that the position is correct, when qualified appropriately. The central claim of virtue epistemology is that, Gettier problems aside, knowledge is true belief which results from a cognitive virtue. In section one I will clarify this claim with some brief remarks about the nature of virtues in general, and cognitive virtues in particular. In section two I will consider two objections to the theory of knowledge which results. In section three of the paper I will argue that virtue epistemology can be qualified so as to avoid the objections raised in section two. Finally, I will argue that the amendments which solve the objections of section two also allow us to solve a version of the dreaded generality problem.