Supervenience Physicalism: Meeting the Demands of Determination and Explanation

Abstract

Non-reductive physicalism is currently the most widely held metaphysic of mind. My aim in this essay is to show that supervenience physicalism—perhaps the most common form of non-reductive physicalism—is not a defensible position. I argue that, in order for any supervenience thesis to ground a legitimate form of physicalism, it must yield the right sort of determination relation between physical and non-physical properties. Then I argue that non-reductionism leaves one without any explanation for the laws that are implied by supervenience theses that deliver this determination relation.     

On characterizing the physical

How should physical entities be characterized? Physicalists, who have most to do with the notion, usually characterize the physical by reference to two components,¹ 1. The physical entities are the entities treated by fundamental physics with the proviso that 2. Physical entities are not fundamentally mental (that is, do not individually possess or bestow mentality). Here I will explore the extent to which appeals to fundamental physics and to the NFM (no fundamental mentality) constraint are appropriate for characterizing the physical, especially for purposes of formulating physicalism. I will motivate and defend a version of an account incorporating both components.     

Constructor theory

Constructor theory seeks to express all fundamental scientific theories in terms of a dichotomy between possible and impossible physical transformations–those that can be caused to happen and those that cannot. This is a departure from the prevailing conception of fundamental physics which is to predict what will happen from initial conditions and laws of motion. Several converging motivations for expecting constructor theory to be a fundamental branch of physics are discussed. Some principles of the theory are suggested and its potential for solving various problems and achieving various unifications is explored. These include providing a theory of information underlying classical and quantum information; generalising the theory of computation to include all physical transformations; unifying formal statements of conservation laws with the stronger operational ones (such as the ruling-out of perpetual motion machines); expressing the principles of testability and of the computability of nature (currently deemed methodological and metaphysical respectively) as laws of physics; allowing exact statements of emergent laws (such as the second law of thermodynamics); and expressing certain apparently anthropocentric attributes such as knowledge in physical terms.     

The Inherent Empirical Underdetermination of Mental Causation

It has become a popular view among non-reductive physicalists that it is possible to devise empirical tests generating evidence for the causal efficacy of the mental, whereby the exclusion worries that have haunted the position of non-reductive physicalism for decades can be dissolved once and for all. This paper aims to show that these evidentialist hopes are vain. I argue that, if the mental is taken to supervene non-reductively on the physical, there cannot exist empirical evidence for its causal efficacy. While causal structures without non-reductive supervenience relations can be conclusively identified in ideal discovery circumstances, it is impossible, in principle, to generate evidence that would favour models with mental causation over models without. Ascribing causal efficacy to the mental, for the non-reductive physicalist, is a modelling choice that must be made on the basis of metaphysical background theories or pragmatic maxims guiding the selection among empirically indistinguishable models.     

Why Colour Primitivism?

Primitivism is the view that colors are sui generis properties of physical objects. The basic insight underlying primitivism is that colours are as we see them, i.e. they are categorical properties of physical objects—simple, monadic, constant, etc.—just like shapes. As such, they determine the content of colour experience. Accepting the premise that colours are sui generis properties of physical objects, this paper seeks to show that ascribing primitive properties to objects is, ipso facto, ascribing to objects irreducible dispositions to look coloured, and that anything that primitive redness can do, the non-reductive disposition to look red can do just as well. What makes primitivism suspect is not the commitment to sui generis properties, but instead the claim that colours are more than dispositions. Since, as I show, whatever primitivism appeals to for the purpose of arguing that colours are more than dispositions—objectivity, explanation, causation, phenomenology, constancy, etc.—can also be invoked by non-reductive dispositionalism, the feature that purportedly renders colours more than dispositions remains mysterious.     

Laws of Nature Don't Have Ceteris Paribus Clauses,They Are Ceteris Paribus Clauses

Laws of nature are properly (if controversially) conceived as abstract entities playing a governing role in the physical universe. Dispositionalists typically hold that laws of nature are not real, or at least are not fundamental, and that regularities in the physical universe are grounded in the causal powers of objects. By contrast, I argue that dispositionalism implies nomic realism: since at least some dispositions have ceteris paribus clauses incorporating uninstantiated universals, and these ceteris paribus clauses help to determine their dispositions' ranges of manifestation, there are indeed abstracta which play a governing role in the physical universe. After addressing several objections (including the objection that such ‘laws’ lack sufficient independence/externality from the dispositions to count as genuinely governing), I go on to consider some broader implications of this conclusion for other debates in metaphysics and the philosophy of science. ¹      

Laws and constrained kinds: a lesson from motor neuroscience

In this paper, I want to explore the question of whether or not there are laws in psychology. Jaegwon Kim has argued (Supervenience and mind. MIT press, Cambridge; 1993; Mind in a physical world. MIT press, Cambridge 1998) that there are no laws in psychology that contain reference to multiply realized kinds, because statements about such kinds fail to be projectible. After reviewing Kim??s argument for this claim, I show how his conclusion hinges on a hidden assumption: that a kind can only feature in a projectible statement if it is defined by an internal physical property. This assumption, however, is false: constrained kinds can feature in projectible statements, and yet they are not defined by any set of internal physical properties. I suggest that many mental terms actually refer to constrained kinds, and give an example from motor neuroscience of a constrained kind that is multiply realizable and ??projectible??: the intention to move voluntarily in a specific direction.     

Contrastive mental causation

Any theory of mind needs to explain mental causation. Kim’s (upward) exclusion argument concludes that non-reductive physicalism cannot meet this challenge. One classic reply is that mental properties capture the causally relevant level of generality, because they are insensitive to physical realization. However, this reply suggests downward exclusion (if mental properties are causally efficacious, their physical realizers are causally impotent), contrary to physicalism’s assumption of closure. This paper shows how non-reductive physicalists can solve this problem by introducing a contrastive account of causation with non-exhaustive contrasts. That view has independent justification, because it is also needed to solve other puzzles. On this theory, both a mental property and its physical realizer can cause the same physical effect without lapsing into any problematic overdetermination when they cause that effect in contrast with distinct foils. This contrastive solution has advantages over previous accounts of mental causation and is defended against objections.

     

Harm in the Wild: Facing Non-Human Suffering in Nature

The paper is concerned with whether the reductio of the natural-harm-argument can be avoided by disvaluing non-human suffering and death. According to the natural-harm-argument, alleviating the suffering of non-human animals is not a moral obligation for human beings because such an obligation would also morally prescribe human intervention in nature for the protection of non-human animal interests which, it claims, is absurd. It is possible to avoid the reductio by formulating the moral obligation to alleviate non-human suffering and death with two constraints: The first concerns the practicability of intervention and establishes a moral obligation to intervene only in cases where this is humanly possible. The other constraint acknowledges that lack of competence in humans can risk producing more harm than good by intervening. A third way of avoiding the problematic version of the natural-harm-argument considers whether human and non-human suffering and death are sufficiently different to allow different types of responses. I argue that the attempt to avoid the reductio of the natural-harm-argument by disvaluing non-human death can only work with an anthropocentric bias, which accords to non-human suffering and death a fundamentally different value and that it fails to dismiss the moral obligation created by the harm that non-human animals face in the wild.     

Similarity, feature discovery, and the size principle

In this paper we consider the “size principle” for featural similarity, which states that rare features should be weighted more heavily than common features in people’s evaluations of the similarity between two entities. Specifically, it predicts that if a feature is possessed by n objects, the expected weight scales according to a 1/n law. One justification of the size principle emerges from a Bayesian analysis of simple induction problems ( [Tenenbaum and Griffiths, 2001a] and [Tenenbaum and Griffiths, 2001b]), and is closely related to work by Shepard (1987) proposing universal laws for inductive generalization. In this article, we (1) show that the size principle can be more generally derived as an expression of a form of representational optimality, and (2) present analyses suggesting that across 11 different data sets in the domains of animals and artifacts, human judgments are in agreement with this law. A number of implications are discussed.     

Causal Exclusion and Causal Autonomism

The causal exclusion problem is often considered as one of the major difficulties for which non-reductive physicalists have no easy solution to offer. Some non-reductive physicalists address this problem by arguing that mental properties are to some extent causally autonomous. If this is the case, then mental properties will not be causally excluded by their physical realizers because causation, in general, is a relation between properties of the same level. In this paper, I argue that the response from causal autonomy cannot be successful for two reasons. First, it does not offer a satisfactory explanation for how mental particulars can have causal efficacy in a non-reductive physicalist framework. Second, the causal considerations underpinning this response do not really support the conclusion that mental properties are causally autonomous.     

Reduction and emergence in the physical sciences: Reply to Rueger

I analyse Rueger’s application of Kim’s model of functional reduction to the relation between the thermal conductivities of metal bars at macroscopic and atomic scales. 1) I show that it is a misunderstanding to accuse the functional reduction model of not accounting for the fact that there are causal powers at the micro-level which have no equivalent at the macro-level. The model not only allows but requires that the causal powers by virtue of which a functional predicate is defined, are only a subset of the causal powers of the properties filling the functional specification. 2) The fact that the micro-equation does not converge to the macro-equation in general but only under the constraint of a “solvability condition” does not show that reduction is impossible, as Rueger claims, but only that reduction requires inter-level constraints. 3) Rueger tries to analyse inter-level reduction with the conceptual means of intra-level reduction. This threatens the coherence of his analysis, given that it makes no sense to ascribe macroproperties such as thermal conductivity to entities at the atomic level. Ignoring the distinction between theses two senses of “reduction” is especially confusing because they have opposite directions: in intra-level reduction, the more detailed account reduces to the less detailed one, whereas in inter-level reduction, the less detailed theory is reduced to the more detailed one. 4) Finally I criticize Rueger’s way of using Wimsatt’s criteria for emergence in terms of non-aggregativity, to construct a concept of synchronic emergence. It is wrong to require, over and above non-aggregativity, irreducibility as a criterion for emergence.     

The role of skin color and facial physiognomy in racial categorization: Moderation by implicit racial attitudes

Previous research has not sufficiently addressed factors that define and moderate racial categorization judgments. This study independently manipulated skin color and facial physiognomy to determine their relative weighting in racial categorization. Participants (N = 250) judged faces varying on 10 levels of facial physiognomy (from Afrocentric to Eurocentric) and 10 levels of skin color (from dark to light) under either no time constraints, a modest time constraint, and under a stringent time constraint. Skin color was a powerful predictor of racial typicality ratings at all levels of facial physiognomy, but participants relied upon facial physiognomy more when rating faces of light than dark skin color. Skin color was a more important cue than facial physiognomy under no time constraints, but as time constraints became more severe, skin color's importance decreased, yet it remained a more important cue at extreme physiognomy levels. The relationship between skin color and racial typicality ratings was stronger for those with more negative implicit racial attitudes. These findings suggest the primary role of skin color in racial categorization and underscore the importance of implicit attitudes in explicit categorization judgments.     

Reconsidering the Role of Bridge Laws In Inter-Theoretical Reductions

The present paper surveys the three most prominent accounts in contemporary debates over how sound reduction should be executed. The classical Nagelian model of reduction derives the laws of the target-theory from the laws of the base theory plus some auxiliary premises (so-called bridge laws) connecting the entities of the target and the base theory. The functional model of reduction emphasizes the causal definitions of the target entities referring to their causal relations to base entities. The new-wave model of reduction deduces not the original target theory but an analogous image of it, which remains inside the vocabulary of the base theory. One of the fundamental motivations of both the functional and the new-wave model is to show that bridge laws can be evaded. The present paper argues that bridge laws—in the original Nagelian sense—are inevitable, i.e. that none of these models can evade them. On the one hand, the functional model of reduction needs bridge laws, since its fundamental concept, functionalization, is an inter-theoretical process dealing with entities of two different theories. Theoretical entities of different theories (in a general heterogeneous case) do not have common causal relations, so the functionalization of an entity—without bridge laws—can only be executed in the framework of its own theory. On the other hand, the so-called images of the new-wave account cannot be constructed without the use of bridge laws. These connecting principles are needed to guide the process of deduction within the base theory; without them one would not be able to recognize if the deduced structure was an image of the target theory.     

Nietzsche and the origin of the idea of modernism

This paper combines a phenomenological account of the types of causal transaction found in social reality with a critique of two theories, one structuralist and one Marxist, that contravene it. Part I argues that there are three types of causal transaction in social life in addition to physical causal transactions: people bringing about states of affairs by acting, states of affairs bringing about actions by inducing responses, and entities and states of affairs bringing about what makes sense to people to do by making certain factors determine this. It is also contended that social formations and structures cause actions and other social formations/structures only by way of participating in these types of transaction. The conditions under which this occurs are discussed. Part II criticizes Peter Blau's account of structural effects and Jean‐Paul Sartre's version of a materialist theory of history, two theories that either advocate or require causal transactions between social structures/ formations which do not reduce to transactions of the types described in Part I. The paper concludes by suggesting that social entities that make actions possible do not thereby cause them.     

Emergence and reduction in dynamical cognitive science

This paper examines the widespread intuition that the dynamical approach to cognitive science is importantly related to emergentism about the mind. The explanatory practices adopted by dynamical cognitive science rule out some conceptions of emergence; covering law explanations require a deducibility relationship between explanans and explanandum, whereas canonical theories of emergence require the absence of such deducibility. A response to this problem - one which would save the intuition that dynamics and emergence are related - is to reconstrue the concept of emergence as a relationship between laws. I call this “nomological emergence” and comment on the extent to which dynamicists would find it acceptable. Alternatively, dynamical cognitive science might be viewed as fitting better with the kind of “functional reductionism” which has recently been developed by authors such as Jaegwon Kim. Which of these two alternatives is preferable remains an open question pending the further development of dynamical cognitive science, particularly in its “non-classical” forms.     

Naturalness constraints on best systems accounts of laws

According to best systems accounts, laws of nature are generalizations in the best systematization of particular matters of fact. Metrics such as simplicity and strength determine which systematization is best, but these are notoriously language relative. For this reason, David Lewis proposed a constraint on languages of inquiry: all predicates must be natural. This constraint is sometimes interpreted as requiring us to know which natural properties are instantiated in our world prior to scientific theorizing. I argue that this interpretation is incorrect. I provide a better interpretation and show how it undercuts an influential epistemological objection to Lewis's best systems account of laws due to Bas van Fraassen.     

A Defense of Emergence

I defend a physicalistic version of ontological emergence; qualia emerge from the brain, but are physical properties nevertheless. First, I address the following questions: what are the central tenets of physicalistic ontological emergentism; what are the relationships between these tenets; what is the relationship between physicalistic ontological emergentism and non-reductive physicalism; and can there even be a physicalistic version of ontological emergentism? This discussion is merely an attempt to clarify exactly what a physicalistic version of ontological emergentism must claim, and to show that the view is at least coherent. I then defend the view from objections, for example, Kim’s (Philos Stud 95:3–36, 1999) attempt to apply a version of his exclusion argument to ontological emergentism. I conclude by offering a positive argument for the view: given certain empirical evidence concerning the organization of the brain, physicalism might have to endorse ontological emergentism to avoid epiphenomenalism.