Quantum field theory, one of the most rapidly developing areas of contemporary physics, is full of problems of great theoretical and philosophical interest. This collection of essays is the first systematic exploration of the nature and implications of quantum field theory. The contributors discuss quantum field theory from a wide variety of standpoints, exploring in detail its mathematical structure and metaphysical and methodological implications.

Proponents of the view that social structures are ontologically distinct from the people in whose actions they are immanent have assumed that structures can stand in causal relations to individual practices. Were causality to be no more than Humean concomitance correlations between structure and practices would be unproblematic. But two prominent advocates of the ontological account of structures, Bhaskar and Giddens, have also espoused a powers theory of causality. According to that theory causation is brought about by the activity of (...) particulars, in the social psychological case, individuals of some sort. Consistence would demand that structure be those individuals. But neither Giddens nor Bhaskar wish to reify structure to the extent that would fit it for a role as a powerful particular. If only human beings can be powerful particulars in these contexts, the only way that structures can be real must be as properties of conversational interactions. Human action is social just in so far as people direct themselves to engage well in joint activities with others. (shrink)

IN the right circumstances and the right frame of mind we are prepared to make aesthetic appraisals of almost anything, from hills, cottages and cars, to symphonies, people and poems. My problem is to try and set a boundary in at least one direction to the catholicity of this kind of judgement. I want to argue that when we use a word from our aesthetic vocabulary for appraising a theory in science or a proof in mathematics we are not properly (...) to be described as making an aesthetic appraisal, though there are close parallels with our normal use of these words. (shrink)

The justification of a wholly non-Humean conceptual scheme, based upon the idea of enduring individuals with powers, rests in part on the success of such a scheme in resolving the problems bequeathed to us by the Humean tradition and in part must be achieved by a careful construction of the metaphysics of the new scheme itself. By this we mean a thorough exposition of the meaning and interrelations of the concepts of the new scheme. It is to the latter task (...) that we turn in this paper, being satisfied that the power of the scheme to give a rational account of science has been shown, and that its effectiveness in resolving the Humean problems and dilemmas has been amply demonstrated. (shrink)

I propose to elaborate some hints dropped by Mr. Strawson 2 in order to relieve those pressures of language that have led philosophers to pose and attempt to answer the pseudo-question, “How is induction justified?” Once the source of these pressures is exposed we can turn our attention to the real problems of induction, namely how particular inductive procedures are justified, without feeling that a deeper problem remains always to be solved.

The conceptual problems raised by the discovery of quantum effects have not been fully resolved after half a century. Part of the reason for this is undoubtedly to be found in the mutual ignorance which prevails between physicists and philosophers. In his book Heisenberg brings together a philosophically inclined temperament with an unrivalled knowledge of physics. The result is a book of very great interest, however much one might disagree with his conclusions. The collection of essays of which the other (...) book is made up is intended to bring crucial conceptual problems in physics especially to the notice of philosophers. The design and intention of the collection is admirable for this is the proper way to overcome the departmentalization of interest that has left the deep conceptual problems still unresolved. Men like Heisenberg who combine philosophical temperament with scientic knowledge of great distinction are rare, and yet the difficulties can only be cleared up by the application of philosophical techniques of analysis to problems which are an intimate and difficult part of physics. (shrink)

There is now a well-established distinction recognized in the ways simplicity considerations enter into science. Laws of nature may be graded either with regard to their simplicity of form or with regard to the fewness of the concepts employed to express them. I shall distinguish these as formal simplicity and conceptual simplicity respectively. Dr. J. O. Wisdom suggests that it should be fewness of non-instantial concepts that serves as the guide for making judgements of relative simplicity; a “non-instantial” concept being (...) a concept which is constructed for the purpose of theory, its meaning not being derived simply from experience. Hence non-instantial concepts are, from a logical point of view, to be contrasted with the concepts used to express and record observations directly, that is with instantial concepts representing observables. This seems to be too narrow a restriction on the reduction of concepts. Clearly an advance towards simplicity has been made not only when e.g. a non-instantial concept like “force of gravity” is eliminated from our technical language, but also when the number of instantial concepts is reduced by redefinition, in terms of a smaller number of observables. For example a great simplification was surely made when space-traversed, time taken and mass were chosen as the dynamic “simples”, for the multiplicity of kinds of motion were found to be expressible as functions of these concepts. “Motion” is not non-instantial in the same way as “force of gravity” or “kinetic energy” is non-instantial. However, once this extension to instantial concepts is made there is no need to quarrel with the form/concept distinction as marking a pritma facie difference in criteria of some methodological importance; for a choice say to concentrate on using the fewest concepts does, and one would be inclined to think must , lead to a “decrease” in the formal simplicity of the laws of nature. (shrink)

The justification of a wholly non-Humean conceptual scheme, based upon the idea of enduring individuals with powers, rests in part on the success of such a scheme in resolving the problems bequeathed to us by the Humean tradition and in part must be achieved by a careful construction of the metaphysics of the new scheme itself. By this we mean a thorough exposition of the meaning and interrelations of the concepts of the new scheme. It is to the latter task (...) that we turn in this paper, being satisfied that the power of the scheme to give a rational account of science has been shown, and that its effectiveness in resolving the Humean problems and dilemmas has been amply demonstrated. (shrink)