Since the mid-twentieth century, the concept of the Turing machine has dominated thought about effective procedures. This paper presents an alternative to Turing's analysis; it unifies, refines, and extends my earlier work on this topic. I show that Turing machines cannot live up to their billing as paragons of effective procedure; at best, they may be said to provide us with mere procedure schemas. I argue that the concept of an effective procedure crucially depends upon distinguishing procedures as definite courses (...) of action(- types) from the particular courses of action(-tokens) that actually instantiate them and the causal processes and/or interpretations that ultimately make them effective. On my analysis, effectiveness is not just a matter of logical form; `content' matters. The analysis I provide has the advantage of applying to ordinary, everyday procedures such as recipes and methods, as well as the more refined procedures of mathematics and computer science. It also has the virtue of making better sense of the physical possibilities for hypercomputation than the received view and its extensions, e.g. Turing's o-machines, accelerating machines. (shrink)

This book is intended to be used as a textbook by students of mathematics, and also within limitations as a reference work.

This study provides a unified theory of properties, relations, and propositions (PRPs). Two conceptions of PRPs have emerged in the history of philosophy. The author explores both of these traditional conceptions and shows how they can be captured by a single theory.

This book tackles the issues that arise in connection with intensional logic -- a formal system for representing and explaining the apparent failures of certain important principles of inference such as the substitution of identicals and existential generalization -- and intentional states --mental states such as beliefs, hopes, and desires that are directed towards the world. The theory offers a unified explanation of the various kinds of inferential failures associated with intensional logic but also unifies the study of intensional contexts (...) and intentional states by grounding the explanation of both phenomena in a single theory. When an axiomatized realm of abstract entities is added to the metaphysical structure of the world, we can use them to identify and individuate the contents of directed mental states. The special abstract entities can be viewed as the objectified contents of mental files, and they play a crucial role in the analysis of truth conditions of the sentences involved in inferential failures. (shrink)

Chapter One: Constructions. Entities, constructions, and functions When one travels from Los Angeles to New York, going, say, by way of St. Louis, Chicago, ...

The modern (Russellian) theory of definition conceives definitions as abbreviations, so that the question of adequateness (let alone of truth-value) of definitions becomes meaningless. In this paper we show that beside Russellian conception of definitions understood as abbreviations, there is an Aristotelian conception, which exploits the notion of essence and that this conception can be rehabilitated from the standpoint of the modern logic (in particular by means of Pavel Tichý’s Transparent Intensional Logic). Also Carnap’s ‘explication’ indicates that what we feel (...) to be a definition is frequently distinct from a Russellian definition. (shrink)

The purpose of this article is to provide a non‐contradictory interpretation of sentences such as “Smith's murderer might not have murdered Smith”. An anti‐actualist, two‐dimensional framework including partial functions provides the basis for my solution. I argue for two claims. The modal profile of the proposition expressed by “The F might not have been an F” is complex: at any world where there is a unique F the proposition is true; at any world without a unique F the proposition has (...) no truth‐value; hence, at no world is it false. It remains an open semantic and epistemological question which of the first two kinds of world the actual world is. The semantic method should be based on explicit intensionalization in lieu of actualism. Actualism accords a privileged role to the actual world. Explicit intensionalization places all possible worlds, including the actual one, on an equal footing. Syntactically, a lambda‐bound world variable replaces the actual‐world constant or operator, while the other world variable is existentially bound. (shrink)

This paper defendsintensional essentialism: a property (intensional entity) is not essential relative to an individual (extensional entity), but relative to other properties (or intensional entities). Consequently, an individual can have a property only accidentally, but in virtue of having that property the individual has of necessity other properties. Intensional essentialism is opposed to various aspects of the Kripkean notion of metaphysical modality, eg, varying domains, existence as a property of individuals, and its category of properties which are both empirical and (...) essential with respect to particular individuals and natural kinds. The key notion of intensional essentialism isrequisite. A requisite is explicated as a relation-in-extension between two intensions (functions from possible worlds and moments of time)X, Y such that wherever and wheneverX is instantiatedY is also instantiated. We predict three readings of the sentence. Every wooden table is necessarily wooden , one involving modalityde re and the other two modalityde dicto. The first reading claims that no individual which is a wooden table is necessarily wooden. The claim is backed up by bare particular anti-essentialism. The two other interpretations claim that it is necessary that whatever is a wooden table is wooden. However, as we try to show, one is logically far more perspicuous thanks to the concept of requisite and thus preferable to more standardde dicto formalizations. (shrink)

Questions of definedness are ubiquitous in mathematics. Informally, these involve reasoning about expressions which may or may not have a value. This paper surveys work on logics in which such reasoning can be carried out directly, especially in computational contexts. It begins with a general logic of partial terms, continues with partial combinatory and lambda calculi, and concludes with an expressively rich theory of partial functions and polymorphic types, where termination of functional programs can be established in a natural way.

Expressions in a language, whether words, phrases, or sentences, have meanings. So it seems reasonable to suppose that there are meanings that expressions have. Of course, it is fashionable in some philosophical circles to deny this.

This book makes a stimulating contribution to the philosophy of language and philosophy of mind. It begins with a spirited defence of the view that propositions are structured and that propositional structure is 'psychologically real'. The author then develops a subtle view of propositions and attitude ascription. The view is worked out in detail with attention to such topics as the semantics of conversations, iterated attitude ascriptions, and the role of propositions as bearers of truth. Along the way important issues (...) in the philosophy of mind are addressed. Though intended primarily for professional philosophers and graduate students the book will also interest cognitive scientists and linguists. (shrink)

The Kantian idea that some judgments are synthetic even in the area of a priori judgments cannot be accepted in its original version, but a modification of the notions analytic' and 'synthetic' discovers a rational core of that idea. The new definition of 'analytic' concerns concepts and makes it possible to distinguish between analytic concepts, which are effective ways of computing recursive functions, and synthetic concepts, which either define non-recursive functions, or define recursive functions in an ineffective way. To justify (...) this claim we have to construe concepts as abstract procedures not reducible to set-theoretical entities. (shrink)