Orly Shenker

Special sciences (such as biology, psychology, economics) describe various regularities holding at some high macroscopic level. One of the central questions concerning these macroscopic regularities is how they are related to the laws of physics governing the underlying microscopic physical reality. In this paper we show how a macroscopic regularity may emerge from an underlying micro- scopic structure, and how the appearance of multiple realizability of the special sciences by physics comes about in a reductionist-physicalist framework. On this basis we explain how complexity at the high level can arise due to a sort of harmony between the microscopic dynamics and observer-dependent macroscopic properties. We show that observer-dependent properties, which underlie the emergence of macroscopic properties and of macroscopic complexity, are objective physical facts. We argue that such physical properties remove the mystery from the multiple realizability of special sciences’ kinds, since the latter are grounded in shared physical properties. Finally we explain how and in what sense in our reductive physicalist approach the special sciences are still autonomous after all.

According to influential views the probabilities in classical statistical mechanics and other special sciences are objective chances, although the underlying mechanical theory is deterministic, since the deterministic low level is inadmissible or unavailable from the high level. Here two intuitions pull in opposite directions: One intuition is that if the world is deterministic, probability can only express subjective ignorance. The other intuition is that probability of high-level phenomena, especially thermodynamic ones, is dictated by the state of affairs in the world. We argue in support of this second intuition and we show that in fact there are two different ways in which high-level probability describes matters of fact, even if the underlying microscopic reality is deterministic. Our analysis is novel, but supports approaches by, e.g., Loewer, Albert, Frigg and Hoefer, List and Pivato. In particular, the reductive view we propose here can be seen as a naturalization of the above approaches. We consider consequences of our result for nonreductive physicalist approaches, such as functionalism, that admit multiple realization of the kinds that appear in the special sciences by physical kinds. We show that nonreductive physicalism implies the existence of nonphysical matters of fact.

Statistical mechanics is the name of the ongoing attempt to explain and predict certain phenomena, above all those described by thermodynamics on the basis of the fundamental theories of physics, in particular mechanics, together with certain auxiliary assumptions. In another paper in this journal, Foundations of statistical mechanics: Mechanics by itself, I have shown that some of the thermodynamic regularities, including the probabilistic ones, can be described in terms of mechanics by itself. But in order to prove those regularities, in particular the time asymmetric ones, it is necessary to add to mechanics assumptions of three kinds, all of which are under debate in contemporary literature. One kind of assumptions concerns measure and probability, and here, a major debate is around the notion of “typicality.” A second assumption concerns initial conditions, and here, the debate is about the nature and status of the so-called past hypothesis. The third kind of assumptions concerns the dynamics, and here, the possibility and significance of “Maxwell's Demon” is the main topic of discussions. This article describes these assumptions and examines the justification for introducing them, emphasizing the contemporary debates around them.

Multiple realizability seems to be empirically justified and provides the conceptual basis for the autonomy of the special sciences. But it is mysterious. In this talk I propose a new reductionist approach to the special sciences that removes the mystery: I explain why the special sciences kinds appear to be multiply realized although they are identical with physical kinds and in what sense the special sciences kinds and laws are autonomous although they are physical laws. This approach is based on the approach by Hemmo & Shenker to the reduction of thermodynamics to statistical mechanics.

We discuss a recent proposal by Albert to recover thermodynamics on a purely dynamical basis, using the quantum theory of the collapse of the wave function of Ghirardi, Rimini and Weber. We propose an alternative way to explain thermodynamics within no-collapse interpretations of quantum mechanics. Our approach relies on the standard quantum mechanical models of environmental decoherence of open systems, \eg Joos and Zeh and Zurek and Paz. This paper presents the two approaches and discusses their advantages. The problems they face will be discussed in a sequel.

We present a novel reductive theory of type-identity physicalism, which is inspired by the foundations of statistical mechanics as a general theory of natural kinds. We show that all the claims mounted against type-identity physicalism in the literature don’t apply to Flat Physicalism, and moreover that this reductive theory solves many of the problems faced by the various non-reductive approaches including functionalism. In particular, we show that Flat Physicalism can account for the appearance of multiple realizability in the special sciences, and that it gives a novel account of the genuine autonomy of the kinds and laws in the special sciences. We further show that the thesis of genuine multiple realization, which is compatible with all forms of non-reductive approaches including functionalism, implies what we call token-dualism; namely the idea that in every token there are non-physical facts, which may either be non-physical properties or some non-physical substance. In other words, we prove that non-reductive kinds necessarily assume non-reductive tokens, i.e., token dualism. Finally, we show that all forms of non-reductive approaches including functionalism imply a literally multi-leveled structure of reality.

In our book The Road to Maxwell’s Demon (RMD) (Cambridge University Press 2012) we proposed a new outline for a reductive account of statistical mechanics in which thermodynamics is reduced to classical mechanics. In a recent review Valia Allori says that we misunderstood Boltzmann’s account of statistical mechanics with respect to two issues: (1) the nature of typicality considerations in Boltzmann’s explanation of the Second Law - and here she provides no argument whatsoever; and (2) Boltzmann’s notion of probability. As to the second issue, unfortunately, there are flaws in her presentation of Boltzmann’s work as well as of ours. In this paper we briefly explain the difference between Boltzmann’s notion of probability and our notion, how the latter in fact complements Boltzmann’s ideas, and Allori’s flaws on these issues.

Interventionism is an approach to the foundations of statistical mechanics which says that to explain and predict some of the thermodynamic phenomena we need to take into account the inescapable effect of environmental perturbations on the system of interest, in addition to the system's internal dynamics. The literature on interventionism suffers from a curious dual attitude: the approach is often mentioned as a possible framework for understanding statistical mechanics, only to be quickly and decidedly dismissed. The present paper is an attempt to understand this attraction-repulsion story. It offers a version of interventionism that appears to be defensible, and shows that this version can meet the main objections raised against it. It then investigates some of the philosophical ideas underlying interventionism, and proposes that these may be the source of the resentment interventionism encounters. This paves the way to see some features and consequences of interventionism, often taken to be shortcomings, as philosophically advantageous.

In a previous article, we have demonstrated by a general phase space argument that a Maxwellian Demon is compatible with statistical mechanics. In this article, we show how this idea can be put to work in the prevalent model of the Demon, namely, a particle-in-a-box, used, for example, by Szilard and Bennett. In the literature, this model is used in order to show that a Demon is incompatible with statistical mechanics, either classical or quantum. However, we show that a detailed phase space analysis of this model illustrates that a Maxwellian Demon is compatible with statistical mechanics.

The appearance of multiple realization of the special sciences kinds by physical kinds can be fully explained within a type-identity reductive physicalist framework, based on recent findings in the foundations of statistical mechanics. This has been shown in Hemmo and Shenker. However, while this account is available for special sciences like biology and thermodynamics, it is unavailable for psychology. Therefore the only coherent physicalist account of psychology is a type-type identity account. The so-called “non reductive” physicalism turns out to be an incoherent idea, and functionalism and supervenience cannot salvage it. At the same time, within a type-identity account properly understood one can give a full account of the anomaly of psychology and understand in what sense the special sciences - including psychology - are autonomous.

Is freedom compatible with determinism? Davidson famously rephrased this question by replacing “freedom” with “anomaly of the mental”, that is, failure to fall under a law. In order to prove that the anomaly of the mental is compatible with other conjectures he makes, in particular that: there is psycho-physical causation; “where there is causality, there must be a law” ; and the mental supervenes on the physical, Davidson proposed a model, that came to be known as anomalous monism. Accepting all of Davidson’s conjectures, we compare the structure of Davidson’s argument with that of Einstein’s argument for the special theory of relativity. This leads us to an exposition of Davidson’s ontology in terms that are inspired by recent results in the philosophy of physics, that is, in terms of fundamental ontology and high-level coarse-grained descriptions. We explain in what sense Davidson’s model is a principle theory and discuss some requirements that the constructive theory underlying Davidson's principle approach must satisfy. We propose two constructive theories of description that may underlie Davidson's approach and this deeper structure leads us to formulating a dilemma according to which Davidson's approach entails either a non-physicalist type-identity reductive and monistic structure of events; or else it entails a structure of events that requires what we call token-substance dualism. We consider some issues which seem to suggest that the first horn of this dilemma collapses into a reductive type-identity physicalist theory, contrary to Davidson's intent. Finally, we show how Davidson's achievement of accounting for some freedom of the mental from the physical and the anomaly of the mental within anomalous monism can be achieved in a fully reductive type-identity physicalist theory.

Reductive physicalism is a minority view in contemporary philosophy as well as in science, and therefore arguments for endorsing it often amount to arguments against the alternative views, in particular so-called non-reductive physicalism. In this paper we put forward a new argument for reductive physicalism, according to which it is the best account of the empirical data that we have. In particular, we show that: (a) a reductive physicalist theory of the mind forms an essential part of the very argument for the existence of an external world: if one rejects psychophysical identity physicalism, one’s case for believing in the existence of an external world is substantially weakened; and (b) the success of a physical account of the mind is the most important criterion for the success of (future) physics; and (c) reductive physicalism is the only approach in which relying on science in order to account for the external world makes sense; and finally, (d) within reductive physicalism, one can provide a new criterion for theory preference in science, and a new argument for scientific realism. In our physicalist view the experience forms the initial data, which is then reduced to fundamental physics.

According to contemporary computational neuroscience the mental is associated with computations implemented in the brain. We analyze in physical terms based on recent results in the foundations of statistical mechanics two well-known (independent) problems that arise for this approach: the problem of multiple-computations and the problem of multiple-realization. We show that within the computational theory of the mind the two problems are insoluble by the physics of the brain. We further show that attempts to solve the problems by the interactions of the systems implementing the computations with an environment (in or outside the brain) must introduce non- physical factors, and therefore fail on physical grounds. We also show that the problems are endemic and pertain to other forms of functional theories of the mind, most notably, causal functionalism. Finally, we propose a physicalist reductive identity theory, which is a generalization of statistical mechanics for all the special sciences, and show that only a theory of this kind can provide physical solutions to the above two problems in computational neuroscience. We conclude that functionalism in the theory of mind must be replaced with a reductive identity theory. This result has far-reaching implications with respect to the research programs in brain science.

This volume provides a broad perspective on the state of the art in the philosophy and conceptual foundations of quantum mechanics. Its essays take their starting point in the work and influence of Itamar Pitowsky, who has greatly influenced our understanding of what is characteristically non-classical about quantum probabilities and quantum logic, and this serves as a vantage point from which they reflect on key ongoing debates in the field. Readers will find a definitive and multi-faceted description of the major open questions in the foundations of quantum mechanics today, including: Is quantum mechanics a new theory of (contextual) probability? Should the quantum state be interpreted objectively or subjectively? How should probability be understood in the Everett interpretation of quantum mechanics? What are the limits of the physical implementation of computation? The impact of this volume goes beyond the exposition of Pitowsky’s influence: it provides a unique collection of essays by leading thinkers containing profound reflections on the field.