Ioannis G. Ntagkas

There are significant problems involved in determining the ontology of quantum field theory. An ontology involving particles seems to be ruled out due to the problem of defining localized position operators, issues involving interactions in QFT, and, perhaps, the appearance of unitarily inequivalent representations. While this might imply that fields are the most natural ontology for QFT, the wavefunctional interpretation of QFT has significant drawbacks. A modified field ontology is examined where determinables are assigned to open bounded regions of spacetime instead of spacetime points.

Many attempts have been made to provide Quantum Field Theory with conceptually clear and mathematically rigorous foundations; remarkable examples are the Bohmian and the algebraic perspectives respectively. In this essay we introduce the dissipative approach to QFT, a new alternative formulation of the theory explaining the phenomena of particle creation and annihilation starting from nonequilibrium thermodynamics. It is shown that DQFT presents a rigorous mathematical structure, and a clear particle ontology, taking the best from the mentioned perspectives. Finally, after the discussion of its principal implications and consequences, we compare it with the main Bohmian QFTs implementing a particle ontology.

Candidates for fundamental physical laws rarely, if ever, employ higher than second time derivatives. Easwaran sketches an enticing story that purports to explain away this puzzling fact and thereby provides indirect evidence for a particular set of metaphysical theses used in the explanation. I object to both the scope and coherence of Easwaran's account, before going on to defend an alternative, more metaphysically deflationary explanation: in interacting Lagrangian field theories, it is either impossible or very hard to incorporate higher than second time derivatives without rendering the vacuum state unstable. The so-called Ostrogradski instability represents a powerful constraint on the construction of new field theories and supplies a novel, largely overlooked example of non-causal explanation in physics.

Effective Field Theory (EFT) is the successful paradigm underlying modern theoretical physics, including the "Core Theory" of the Standard Model of particle physics plus Einstein's general relativity. I will argue that EFT grants us a unique insight: each EFT model comes with a built-in specification of its domain of applicability. Hence, once a model is tested within some domain (of energies and interaction strengths), we can be confident that it will continue to be accurate within that domain. Currently, the Core Theory has been tested in regimes that include all of the energy scales relevant to the physics of everyday life (biology, chemistry, technology, etc.). Therefore, we have reason to be confident that the laws of physics underlying the phenomena of everyday life are completely known.

There was a revolutionary theoretical development in high-energy physics in the 1970s: physicists developed what became known as the standard model. If we are to take seriously claims made about the explanatory power and especially the high degree of unity of the standard model then, the dissertation argues, we are committed to a robustly realistic interpretation of the standard model. The central theoretical tool of the standard model is quantum field theory. The dissertation analyzes the conceptual structure of quantum field theory and takes up the task of articulating a realistic interpretation of quantum field theory in the standard model closely tied to high-energy physicists' own interpretation of the theory. Any attempt at a realistic interpretation of quantum field theory qua field theory involves widening the concept of a field to include objective propensities as real properties, a move this dissertation defends at length. Finally, the dissertation articulates a notion of propensities in quantum field theory, and concludes that while there is certainly much work to be done to fill out a coherent realistic interpretation of quantum field theory , rumors of the impossibility of this task have been greatly exaggerated

The goal of this paper is to show how scientific explanation functions in the context of idealized models. It argues that the aspect of explanation most urgently requiring investigation is the nature of the connection between global theories and explanatory local models. This aspect is neglected in traditional accounts of explanation. The paper examines causal, minimal model, and structural accounts of model-based explanation. It argues that they too fail to offer an account of the connection with global theory that can justify the explanatory power of an idealized local model, and consequently these accounts are unable effectively to distinguish explanatory from non-explanatory models. On the account proposed here, scientific explanation requires theoretical integration between the local model described in the explanation and a global theory with independent explanatory power.

This paper explores the role of physically impossible idealizations in model-based explanation. We do this by examining the explanation of gravitational waves from distant stellar objects using models that contain point-particle idealizations. Like infinite idealizations in thermodynamics, biology and economics, the point-particle idealization in general relativity is physically impossible. What makes this case interesting is that there are two very different kinds of models used for predicting the same gravitational wave phenomena, post-Newtonian models and effective field theory models. The paper contends that post-Newtonian models are explanatory while effective field theory models are not, because only in the former can we eliminate the physically impossible point-particle idealization. This suggests that, in some areas of science at least, models invoking ineliminable infinite idealizations cannot have explanatory power.

Proponents of mechanistic explanations have recently proclaimed that all explanations in the neurosciences appeal to mechanisms. The purpose of the paper is to critically assess this statement and to develop an integrative account that connects a large range of both mechanistic and dynamical explanations. I develop and defend four theses about the relationship between dynamical and mechanistic explanations: that dynamical explanations are structurally grounded, that they are multiply realizable, possess realizing mechanisms and provide a powerful top-down heuristic. Four examples shall support my points: the harmonic oscillator, the Haken–Kelso–Bunz model of bimanual coordination, the Watt governor and the Gierer–Meinhardt model of biological pattern formation. I also develop the picture of “horizontal” and “vertical” directions of explanations to illustrate the different perspectives of the dynamical and mechanistic approach as well as their potential integration by means of intersection points.

The goal of the paper is to develop and propose a general model of the state space of AI. Given the breathtaking progress in AI research and technologies in recent years, such conceptual work is of substantial theoretical interest. The present AI hype is mainly driven by the triumph of deep learning neural networks. As the distinguishing feature of such networks is the ability to self-learn, self-learning is identified as one important dimension of the AI state space. Another dimension is recognized as generalization, the possibility to go over from specific to more general types of problems. A third dimension is semantic grounding. Our overall analysis connects to a number of known foundational issues in the philosophy of mind and cognition: the blockhead objection, the Turing test, the symbol grounding problem, the Chinese room argument, and use theories of meaning. It shall finally be argued that the dimension of grounding decomposes into three sub-dimensions. And the dimension of self-learning turns out as only one of a whole range of “self-x-capacities” (based on ideas of organic computing) that span the self-x-subspace of the full AI state space.

This book provides a thorough and up-to-date introduction to the philosophy of quantum physics. Although quantum theory is renowned for its spectacular empirical successes, controversial discussion about how it should be understood continue to rage today. In this volume, the authors provide an overview of its numerous philosophical challenges: Do quantum objects violate the principle of causality? Are particles of the same type indistinguishable and therefore not individual entities? Do quantum objects retain their identity over time? How does a compound quantum system relate to its parts? These questions are answered here within different interpretational approaches to quantum theory. Finally, moving to Quantum Field Theory, we find that the problem of non-locality is exacerbated. Philosophy of quantum physics is aimed at philosophers with an interest in physics, while also serving to familiarize physicists with many of the essential philosophical questions of their subject.

In this paper I elicit a prediction from structural realism and compare it, not to a historical case, but to a contemporary scientific theory. If structural realism is correct, then we should expect physics to develop theories that fail to provide an ontology of the sort sought by traditional realists. If structure alone is responsible for instrumental success, we should expect surplus ontology to be eliminated. Quantum field theory (QFT) provides the framework for some of the best confirmed theories in science, but debates over its ontology are vexed. Rather than taking a stand on these matters, the structural realist can embrace QFT as an example of just the kind of theory SR should lead us to expect. Yet, it is not clear that QFT meets the structuralist's positive expectation by providing a structure for the world. In particular, the problem of unitarily inequivalent representations threatens to undermine the possibility of QFT providing a unique structure for the world. In response to this problem, I suggest that the structuralist should endorse pluralism about structure.

Epiphenomenalism is the view that phenomenal properties – which characterize what it is like, or how it feels, for a subject to be in conscious states – have no physical effects. One of the earliest arguments against epiphenomenalism is the evolutionary argument (James 1890/1981; Eccles and Popper 1977; Popper 1978), which starts from the following problem: why is pain correlated with stimuli detrimental to survival and reproduction – such as suffocation, hunger and burning? And why is pleasure correlated with stimuli beneficial to survival and reproduction – such as eating and breathing? According to the argument, the fact that we have these particular correlations and not other ones must have an evolutionary explanation. But given epiphenomenalism, differences in phenomenal properties could not cause differences in fitness, so natural selection would not be expected to favor these correlations over any other ones. Epiphenomenalism thus renders these correlations an inexplicable coincidence, and should therefore be rejected. The evolutionary argument has been widely criticized and few have deemed it cogent (Broad 1925; Jackson 1982; Robinson 2007; Corabi 2014). In this paper, I will consider previous and potential criticisms and conclude some of them are indeed fatal to the argument if it is understood, as it traditionally has been, as an argument for any standard version of non-epiphenomenalism such as physicalism and interactionism. I will then offer a new and improved version of the argument, as an argument for a particular non-epiphenomenalist view, which I will call the phenomenal powers view. This is the view that phenomenal properties produce and thereby (metaphysically) necessitate their effects in virtue of how they feel, or in virtue of their intrinsic, phenomenal character alone – along the lines of C. B. Martin and John Heil’s powerful qualities view (Martin and Heil 1999; Heil 2003). I will argue that the phenomenal powers view explains the correlations given natural selection far better than any other view. It follows that if (and only if) understood as an argument for the phenomenal powers view, the evolutionary argument is far stronger than it is usually thought to be.

The article discusses the relationship between John Searle’s doctrine of naturalism and various forms of materialism and dualism. It is argued that despite Searle’s protestations, his doctrine is not substantially differ- ent from the epiphenomenalistic property dualism, except for the admis- sion, in his later works, of the existence of an irreducible non-Humean self. In particular, his recognition that consciousness is unique in having an irreducible first-person ontology makes his disavowal of property du- alism purely verbalistic. As for epiphenomenalism, Searle’s explanation of how consciousness can be efficacious without violating the causal clo- sure of the physical, by analogy with the causal efficacy of the higher level properties of physical objects that are supervenient on the microphysical, confuses causality and constitution (causal and constitutive superve- nience). It is also argued that Searle’s recognition of the existence of an irreducible non-Humean self that is responsible for decision-making sits badly both with his (property dualistic) view that conscious mental states are irreducibly first-personal states of the brain (rather than of the self) and with his (epiphenomenalistic) view that consciousness has no causal power in addition to that of the underlying neurobiology.

After rejecting substance dualism, some naturalists embrace patternism. It states that persons are bodies and that bodies are material machines running abstract person programs. Following Aristotle, these person programs are souls. Patternists adopt four-dimensionalist theories of persistence: Bodies are 3D stages of 4D lives. Patternism permits at least six types of life after death. It permits quantum immortality, teleportation, salvation through advanced technology, promotion out of a simulated reality, computational monadology, and the revision theory of resurrection.

Unity of science was once a very popular idea among both philosophers and scientists. But it has fallen out of fashion, largely because of its association with reductionism and the challenge from multiple realisation. Pluralism and the disunity of science are the new norm, and higher-level natural kinds and special science laws are considered to have an important role in scientific practice. What kind of reductionism does multiple realisability challenge? What does it take to reduce one phenomenon to another? How do we determine which kinds are natural? What is the ontological basis of unity? In this Element, Tuomas Tahko examines these questions from a contemporary perspective, after a historical overview. The upshot is that there is still value in the idea of a unity of science. We can combine a modest sense of unity with pluralism and give an ontological analysis of unity in terms of natural kind monism. This title is available as Open Access on Cambridge Core.

The mind-body problem is analyzed in a physicalist perspective. By combining the concepts of emergence and algorithmic information theory in a thought experiment employing a basic nonlinear process, it is argued that epistemically strongly emergent properties may develop in a physical system. A comparison with the significantly more complex neural network of the brain shows that also consciousness is epistemically emergent in a strong sense. Thus reductionist understanding of consciousness appears not possible; the mind-body problem does not have a reductionist solution. The ontologically emergent character of consciousness is then identified from a combinatorial analysis relating to system limits set by quantum mechanics, implying that consciousness is fundamentally irreducible to low-level phenomena. In the perspective of a modified definition of free will, the character of the physical interactions of the brain's neural system is subsequently studied. As an ontologically open system, it is asserted that its future states are undeterminable in principle. We argue that this leads to freedom of the will.

Under current UK legislation, only a man can commit rape. This paper argues that this is an unjustified double standard that reinforces problematic gendered stereotypes about male and female sexuality. I first reject three potential justifications for making penile penetration a condition of rape: it is physically impossible for a woman to rape a man; it is a more serious offence to forcibly penetrate someone than to force them to penetrate you; rape is a gendered crime. I argue that, as these justifications fail, a woman having sex with a man without his consent ought to be considered rape. I then explain some further reasons that this matters. I argue that, not only is it unjust, it is also both a cause and a consequence of harmful stereotypes and prejudices about male and female sexuality: men are ‘always up for sex’; women’s sexual purity is more important than men’s; sex is something men do to women. Therefore, I suggest that, if rape law were made gender neutral, these stereotypes would be undermined and this might make some difference to the problematic ways that sexual relations are sometimes viewed between men and women more generally.

The usual question, “Are models fictions?” is replaced by the question, “Should scientific models be regarded as works of fiction?” This makes it clear that the issue is not one of definition but of interpretation. First one must distinguish between the ontology of scientific models and their function in the practice of science. Theoretical models and works of fiction are ontologically on a par, their both being creations of human imagination. It is their differing functions in practice that makes it inappropriate to regard scientific models as works of fiction. Three reasons for thinking scientific models should be regarded as works of fiction are rejected. First, scientists themselves sometimes invoke the idea of fictions in their discussions of specific models. Second, many scientific models are physically impossible to realize in the real world. Third, regarding scientific models as works of fiction supports a general fictionalist understanding of scientific theories. It is concluded that promoting the general idea that scientific models are works of fiction unnecessarily supports attacks on the legitimacy of science itself.

I defend a causal reductionist account of the nature of rates of change like velocity and acceleration. This account identifies velocity with the past derivative of position and acceleration with the future derivative of velocity. Unlike most reductionist accounts, it can preserve the role of velocity as a cause of future positions and acceleration as the effect of current forces. I show that this is possible only if all the fundamental laws are expressed by differential equations of the same order. Consideration of the continuity of time explains why the differential equations are all second order. This explanation is not available on non-causal or non-reductionist accounts of rates of change. Finally, I argue that alleged counterexamples to the reductionist account involving physically impossible worlds are irrelevant to an analysis of the properties that play a causal role in the actual world. 1 Background2 Grounding3 Causation4 The Proposal5 Why No Third Derivatives?6 Why Any Derivatives?7 Counterexamples?

Philosophy and Phenomenological Research, EarlyView. Despite the acknowledgement of the moral significance of consent there is still much work to be done in determining which specific sexual encounters count as unproblematically consensual. This paper focuses on the impact of deception. It takes up the specific case of deception about one's self. It may seem obvious that one ought not to lie to a sexual partner about who one is, but determining which features of oneself are most relevant, as well as the lies which it follows would be impermissible to tell, is complicated. It is argued here that deception about one's morally valenced character traits, those we think of as virtues and vices, are particularly problematic. This is true regardless of whether knowing the truth about those traits would have made a difference to one's partner's consent. Attention is then drawn to a range of types of lies that one ought not to tell.

A theory of perception must be capable of explaining the full range of conscious perception, including amodal perception. In amodal perception we perceive the world to contain physical features that are not directly detectable by the sensory receptors. According to the active-externalist theory of perception, amodal perception depends on active engagement with perceptual objects. This paper focuses on amodal visual perception and presents a counter-example to the idea that active-externalism can account for amodal perception. The counterexample involves the experience of so-called ‘impossible objects’, objects experienced in perceptual character as having geometrical properties that no physically real object can have

The book is an extended study of the problem of consciousness. After setting up the problem, I argue that reductive explanation of consciousness is impossible, and that if one takes consciousness seriously, one has to go beyond a strict materialist framework. In the second half of the book, I move toward a positive theory of consciousness with fundamental laws linking the physical and the experiential in a systematic way. Finally, I use the ideas and arguments developed earlier to defend a form of strong artificial intelligence and to analyze some problems in the foundations of quantum mechanics.

Behaviorism died very slowly in American psychology. Willing to admit only stimuli and responses, narrowly defined, as the contents of its science, it was too limited to be useful in understanding higher organisms. But it seemed for decades to be the only way to eliminate subjectivism and to make psychology scientific. Cracks in behaviorist orthodoxy began to appear 40 years ago, though physiological psychologists never felt themselves bound by its restrictions. By the 1960s psychologists were openly espousing a new 'cognitive' psychology, admitting to internal states and a mental life beyond overt behavior. It was a step forward, but the block diagrams of the cognitive psychologists still had a stimulus on one end and a response on the other, just like those of the old-fashioned behaviorists. Consciousness, the great problem that got psychology started, was still viewed with alarm as the purview of charlatans and worse.

This paper engages the question ‘Does the consistency of a set of axioms entail the existence of a model in which they are satisfied?’ within the frame of the Frege-Hilbert controversy. The question is related historically to the formulation, proof and reception of Gödel’s Completeness Theorem. Tools from mathematical logic are then used to argue that there are precise senses in which Frege was correct to maintain that demonstrating consistency is as difficult as it can be, but also in which Hilbert was correct to maintain that demonstrating existence given consistency is as easy as it can be.

Artificial intelligence (AI) research enjoyed an initial period of enthusiasm in the 1970s and 80s. But this enthusiasm was tempered by a long interlude of frustration when genuinely useful AI applications failed to be forthcoming. Today, we are experiencing once again a period of enthusiasm, fired above all by the successes of the technology of deep neural networks or deep machine learning. In this paper we draw attention to what we take to be serious problems underlying current views of artificial intelligence encouraged by these successes, especially in the domain of language processing. We then show an alternative approach to language-centric AI, in which we identify a role for philosophy.