The perturbative approach to quantum field theory has long been viewed with suspicion by philosophers of science. This article offers a diagnosis of its conceptual problems. Drawing on Norton’s discussion of the notion of approximation I argue that perturbative QFT ought to be understood as producing approximations without specifying an underlying QFT model. This analysis leads to a reassessment of common worries about perturbative QFT. What ends up being the key issue with the approach on this picture is not mathematical (...) rigour, or the threat of inconsistency, but the need for a physical explanation of its empirical success. 1Three Worries about Perturbative Quantum Field Theory2The Perturbative Formalism 2.1Expanding the S-matrix2.2Perturbative renormalization3Approximations and Models4Perturbative Quantum Field Theory Produces Approximations5The Real Problem. (shrink)

This book argues that a plausible account of emergence requires replacing the traditional assumption that what primarily exists are particular entities with generic processes. Traversing contemporary physics and issues of identity over time, it then proceeds to develop a metaphysical taxonomy of emergent entities and of the character of human life.

The development of a defensible and fecund notion of emergence has been dogged by a number of threshold issues neatly highlighted in a recent paper by Jaegwon Kim. We argue that physicalist assumptions confuse and vitiate the whole project. In particular, his contention that emergence entails supervenience is contradicted by his own argument that the ‘microstructure’ of an object belongs to the whole object, not to its constituents. And his argument against the possibility of downward causation is question-begging and makes (...) false assumptions about causal sufficiency. We argue, on the contrary, for a rejection of the deeply entrenched assumption, shared by physicalists and Cartesians alike, that what basically exists are things (entities, substances). Our best physics tells us that there are no basic particulars, only fields in process. We need an ontology which gives priority to organization, which is inherently relational. Reflection upon the fact that all biological creatures are far-from-equilibrium systems, whose very persistence depend upon their interactions with their environment, reveals incoherence in the notion of an ‘emergence base’. (shrink)

There are two distinct interpretations of the role that Feynman diagrams play in physics: (i) they are calculational devices, a type of notation designed to keep track of complicated mathematical expressions; and (ii) they are representational devices, a type of picture. I argue that Feynman diagrams not only have a calculational function but also represent: they are in some sense pictures. I defend my view through addressing two objections and in so doing I offer an account of representation that explains (...) why Feynman diagrams represent. The account that I advocate is a version of that defended by Kendall Walton, which provides us with a basic characterization of the way that representations in general work and is particularly useful for understanding distinctively pictorial representations - in Walton's terms, depictions. The question of the epistemic function of Feynman diagrams as pictorial representations is left for another time. (shrink)

I examine the construction process of the “Higgs mechanism” and its subsequent use by Steven Weinberg to formulate the electroweak theory of elementary particle physics. I characterize the development of the Higgs mechanism as a historical process that was guided through analogies drawn to the theories of solid-state physics and that was progressive through diverse contributions in the sixties from a number of physicists working independently. I also offer a detailed comparative study of the similarities and the differences that exist (...) between the approaches taken in these contributions. (shrink)

A final version of this paper is in press as: Bickhard, M. H.. The Dynamic Emergence of Representation. In H. Clapin, P. Staines, P. Slezak Representation in Mind: New Approaches to Mental Representation. Praeger.

The received view in philosophical studies of quantum field theory is that Feynman diagrams are simply calculational devices. Alongside this view we have the one that takes virtual quanta to be also simply formal tools. This received view was developed and consolidated in philosophy of physics by Mario Bunge, Paul Teller, Michael Redhead, Robert Weingard, Brigitte Falkenburg, and others. In this article I present an alternative to the received view.

This paper criticizes the traditional philosophical account of the quantization of gauge theories and offers an alternative. On the received view, gauge theories resist quantization because they feature distinct mathematical representatives of the same physical state of affairs. This resistance is overcome by a sequence of ad hoc modifications, justified in part by reference to semiclassical electrodynamics. Among other things, these modifications introduce "ghosts": particles with unphysical properties which do not appear in asymptotic states and which are said to be (...) purely a notational convenience. I argue that this sequence of modifications is unjustified and inadequate, making it a poor basis for the interpretation of ghosts. I then argue that gauge theories can be quantized by the same method as any other theory. On this account, ghosts are not purely notation: they are coordinates on the classical configuration space of the theory—specifically, on its gauge structure. This interpretation does not fall prey to the standard philosophical arguments against the significance of ghosts, due to Weingard. Weingard’s argumentative strategy, properly applied, in fact tells in favor of ghosts’ physical significance. (shrink)

Niels Bohr famously argued that a consistent understanding of quantum mechanics requires a new epistemic framework, which he named complementarity . This position asserts that even in the context of quantum theory, classical concepts must be used to understand and communicate measurement results. The apparent conflict between certain classical descriptions is avoided by recognizing that their application now crucially depends on the measurement context. ;Recently it has been argued that a new form of complementarity can provide a solution to the (...) so-called information loss paradox. Stephen Hawking argues that the evolution of black holes cannot be described by standard unitary quantum evolution, because such evolution always preserves information, while the evaporation of a black hole will imply that any information that fell into it is irrevocably lost---hence a "paradox." Some researchers in quantum gravity have argued that this paradox can be resolved if one interprets certain seemingly incompatible descriptions of events around black holes as instead being complementary. ;In this dissertation I assess the extent to which this black hole complementarity can be undergirded by Bohr's account of the limitations of classical concepts. I begin by offering an interpretation of Bohr's complementarity and the role that it plays in his philosophy of quantum theory. After clarifying the nature of classical concepts, I offer an account of the limitations these concepts face, and argue that Bohr's appeal to disturbance is best understood as referring to these conceptual limits. ;Following preparatory chapters on issues in quantum field theory and black hole mechanics, I offer an analysis of the information loss paradox and various responses to it. I consider the three most prominent accounts of black hole complementarity and argue that they fail to offer sufficient justification for the proposed incompatibility between descriptions. ;The lesson that emerges from this dissertation is that we have as much to learn from the limitations facing our scientific descriptions as we do from the successes they enjoy. Because all of our scientific theories offer at best limited, effective accounts of the world, an important part of our interpretive efforts will be assessing the borders of these domains of description. (shrink)

Abstract Taking the integrated viewpoints of causal theory of reference, cognitive science and the notion of correspondence principles from physics, this paper addresses the problems of creativity, the nature of visual imagery and the manner in which science progresses.

Rom Harré criticizes critical realism for ascribing causal powers to social structures, arguing that it is human individuals, and not social structures, that possess causal powers, and that a false conception of structural causation undermines the emancipatory potential of critical realism. I argue that an interpretation of the category of process as the spatio-temporalization of the category of structure, which underpins much evolutionary theory, provides the conceptual tools to explain how the critical realist transformational model of social activity can escape (...) from Harré’s criticism, leading to a general conception of social development within which various types of evolutionary processes can be identified as particular cases. I then argue that Tony Lawson’s PVRS model provides an evolutionary perspective that enables the conceptualization of coercive power as selective pressure. (shrink)

I describe characteristic phenomena of quantum physics that suggest that reality appears to us in two domains: the open and well-known domain of empirical, material things—the realm of actuality—and a hidden and invisible domain of nonempirical, non-material forms—the realm of potentiality. The nonempirical forms are part of physical reality because they contain the empirical possibilities of the universe and can manifest themselves in the empirical world. Two classes of nonempirical states are discussed: the superposition states of microphysical entities, which are (...) nonempirical because observation destroys them, and the virtual states of material systems, which are nonempirical because they are empty. The non-empirical part to physical reality represents a predetermined and hidden order that exists before it is empirical, and the visible world is an emanation out of it. I discuss consequences for our understanding of human nature, the origin of life, and human values. Reality is an indivisible wholeness that is aware of its processes, like a Cosmic Spirit, and it reveals its awareness in the mindlike properties of elementary processes as well as in the human consciousness. Thus, one is led to G. W. F. Hegel's thesis that the Cosmic Spirit is thinking in us. (shrink)

The existence of quantum correlates of consciousness (QCC) is doubtful from a scientific perspective. But even if their existence were verified, philosophical problems would remain. On the other hand, there could be more to QCC than meets the sceptic's eye: • QCC might be useful or even necessary for a better understanding of conscious experience or quantum physics or both. The main reasons for this are: the measurement problem (the nature of observation, the mysterious collapse of the wave function, etc.), (...) ostensibly shared features of quantum phenomena and conscious phenomena (e.g., complementarity, nonspatiality, acausality, spontaneity, and holism) and connections (ontology, causation, and knowledge), the qualia problem (subjectivity, explanatory gap etc.). But there are many problems, especially questions regarding realism and the nature and role of conscious observers; • QCC are conceptually challenging, because there are definitory problems and some crucial ontological and epistemological shortcomings. It is instructive to compare them with recent proposals for understanding neural correlates of consciousness (NCC). QCC are not sufficient for a quantum theory of mind, nor might they be necessary except perhaps in a very broad sense; • QCC are also empirically challenging. Nevertheless, QCC could be relevant and important for the mindbody problem: QCC might reveal features that are necessary at least for behavioral manifestations of human consciousness. But QCC are compatible with very different proposals for a solution of the mind-body problem. This seems to be both advantageous and detrimental. QCC restrict accounts of nomological identity. The discovery of QCC cannot establish a naturalistic theory of mind alone. But there are also problems with QCC in the framework of other ontologies. (shrink)

This chapter contains sections titled: Highlights of Past Literature Current Work Future Work.

Abstract How is meaning assigned to those terms in a theory which are remote from direct observational instantiation? Models and analogies play a role, but close examination of theories in high energy physics shows that the design of experimental apparatus also influences the interpretation of such terms. Certain apparatus favours certain kinds of effects, and this affects the way mathematical theories are interpreted. In particular track producing apparatus becomes involved with theories in which photonic terms are picked out in the (...) theory. A further conceptual constraint is thus introduced. It is argued that this situation favours the interpretation of dispositional properties as affordances rather than as simple dispositions. (shrink)

Philosophical interpretations of theories generally presuppose that a theory can be presented as a consistent mathematical formulation that is interpreted through models. Algebraic quantum field theory (AQFT) can fit this interpretative model. However, standard Lagrangian quantum field theory (LQFT), as well as quantum electrodynamics and nuclear physics, resists recasting along such formal lines. The difference has a distinct bearing on ontological issues. AQFT does not treat particle interactions or the standard model. This paper develops a framework and methodology for interpreting (...) such informal theories as LQFT and the standard model. We begin by summarizing two minimal epistemological interpretation of non-relativistic quantum mechanics (NRQM): Bohrian semantics, which focuses on communicables; and quantum information theory, which focuses on the algebra of local observables. Schwinger's development of quantum field theory supplies a unique path from NRQM to QFT, where each step is conceptually anchored in local measurements. LQFT and the standard model rely on postulates that go beyond the limits set by AQFT and Schwinger's anabatic methodology. The particle ontology of the standard model is clarified by regarding the standard model as an informal modular theory with a limited range of validity. (shrink)

Kim's argument appears to render causally efficacious emergence impossible: Hume's argument appears to render normative emergence impossible, and, in its general form, it precludes any emergence at all. I argue that both of these barriers can be overcome, and, in fact, that they each constitute reductions of their respective underlying presuppositions. In particular, causally efficacious ontological emergence can be modeled, but only within a process metaphysics, thus avoiding Kim's argument, and making use of non-abbreviatory forms of definition, thus avoiding Hume's (...) argument. I illustrate these points with models of the emergent nature of normative function and of representation. (shrink)

If the general arguments concerning theinvolvement of variation and selection inexplanations of ``fit'' are valid, then variationand selection explanations should beappropriate, or at least potentiallyappropriate, outside the paradigm historisticdomains of biology and knowledge. In thisdiscussion, I wish to indicate some potentialroles for variation and selection infoundational physics – specifically inquantum field theory. I will not be attemptingany full coherent ontology for quantum fieldtheory – none currently exists, and none islikely for at least the short term future. Instead, I wish to (...) engage in some partiallyspeculative interpretations of some interestingresults in this area with the aim ofdemonstrating that variation and selectionnotions might play a role even here. Ifvariation and selection can survive in even asinhospitable and non-paradigmatic a terrain asfoundational physics, then it can surviveanywhere. (shrink)