EMERGENCE, DOWNWARDS CAUSATION AND THE COMPLETENESS OF PHYSICS

The 'completeness of physics' is the key premise in the causal argument for physicalism. Standard formulations of it fail to rule out emergent downwards causation. I argue that it must do this if it is to feature in a valid causal argument for physicalism. Drawing on the notion of conferring causal power, I formulate a suitable principle, 'strong completeness'. I investigate the metaphysical implications of distinguishing this principle from emergent downwards causation, and I argue that categoricalist accounts of properties are better equipped to sustain the distinction than dispositional essentialist accounts. Finally, I argue that the additional evidence needed for strong completeness renders the causal argument otiose for any properties amenable to scientific reduction.     

Formulating Emergence

Emergence is intuitively characterized as dependent novelty. Yet, besides this intuition, several formulations of it were elaborated in the last decades. In this article, after having distinguished between two different varieties of emergence (a weak and a strong one), I aim at providing two formulation schemes for emergence. This could help to explain what emergence is and to clarify and unify the suggested formulations. The general idea behind my schemes is that emergence is partial and qualified dependence of the emergent entities on their emergence bases. After having examined several formulations of emergences and presented my schemes, I shall analyse two interesting consequences of the acceptance of the latter: the in principle compatibility between weak and strong emergence and the idea that micro‐physicalism, i.e., the main competitor of emergentism, may actually come in different degrees of strength, more or less in contrast with emergentism. Eventually, I shall briefly compare my formulation schemes with some other relevantly similar proposals.     

THE RELEVANCE OF EMERGENCE THEORY IN THE SCIENCE–RELIGION DIALOGUE

In this article, I call into question the relevance of emergence theories as presently used by thinkers in the science–religion discussion. Specifically, I discuss theories of emergence that have been used by both religious naturalists and proponents of panentheism. I argue for the following conclusions: (1) If we take the background theory to be metaphysical realism, then there seems to be no positive connection between the reality of emergent properties and the validity of providing reality with a religious interpretation, though one could perhaps construe an argument for the positive ontological status of emergence as a negative case for a religious worldview. (2) To be considered more plausible, religious naturalism should interpret religious discourse from the perspective of pragmatic realism. (3) Panentheistic models of divine causality are unable to avoid ontological dualism. (4) It is not obvious that emergent phenomena and/or properties are nonreducible in the ontological sense of the terms; indeed, the tension between weak and strong emergence makes it difficult for the emergentist to make ontological judgments. My general conclusion is that the concept of emergence has little metaphysical significance in the dialogue between science and theology.     

The Constraint Interpretation of Physical Emergence

I develop a variant of the constraint interpretation of the emergence of purely physical (non-biological) entities, focusing on the principle of the non-derivability of actual physical states from possible physical states (physical laws) alone. While this is a necessary condition for any account of emergence, it is not sufficient, for it becomes trivial if not extended to types of constraint that specifically constitute physical entities, namely, those that individuate and differentiate them. Because physical organizations with these features are in fact interdependent sets of such constraints, and because such constraints on physical laws cannot themselves be derived from physical laws, physical organization is emergent. These two complementary types of constraint are components of a complete non-reductive physicalism, comprising a non-reductive materialism and a non-reductive formalism.     

In Search of Ontological Emergence: Diachronic,But Non-supervenient

Most philosophical accounts of emergence are based on supervenience, with supervenience being an ontologically synchronic relation of determination. This conception of emergence as a relation of supervenience, I will argue, is unable to make sense of the kinds of emergence that are widespread in self-organizing and nonlinear dynamical systems, including distributed cognitive systems. In these dynamical systems, an emergent property is ontological (i.e., the causal capacities of P, where P is an emergent feature, are not reducible to causal capacities of the parts, and may exert a top-down causal influence on the parts of the system) and diachronic (i.e., the relata of emergence are temporally extended, and P emerges as a result of some dynamical lower-level processes that unfold in real time).     

Bhaskar on Open and Closed Systems

Bhaskar’s articulation of his ‘transcendental realism’ includes an argument for a form of causal emergence which would mean the rejection of physicalism, by means of rejecting the causal closure of the physical. His argument is based on an analysis of the conditions for closure, where closed systems manifest regular or Humean relations between events. Bhaskar argues that the project of seeking closure entails commitment to a strong (and implausible) reductionism, which in turn entails the impossibility of science itself; and concludes that we should endorse causal emergence. I argue that Bhaskar’s case grossly overreaches itself; and that he fails to establish the emergentist conclusions which he asserts. Consequently his programme poses no significant threat to physicalism.     

Nancey Murphy's Nonreductive Physicalism

This essay examines Nancey Murphy's commitment to downward causation and develops a critique of that notion based upon the distinction between the causal relevance of a higher-level event and its causal efficacy. I suggest the following: (1) nonreductive physicalism lacks adequate resources upon which to base an assertion of real causal power at the emergent, supervenient level; (2) supervenience's nonreductive nature ought not obscure the fact that it affirms an ontological determination of higher-level properties by those at the lower level; and (3) the notion of divine self-renunciation, while consonant with Murphy's claim of supervenient, divine action, is nonetheless problematic. Throughout, I claim that the question of the causal efficacy of a level is logically independent from the assertion of its conceptual or nomological nonreducibility.     

Emergence for Nihilists

I defend mereological nihilism, the view that there are no composite objects, against a challenge from ontological emergence, the view that some things have properties that are ‘something over and above’ the properties of their parts. As the nihilist does not believe in composite wholes, there is nothing in the nihilist's ontology to instantiate emergent properties – or so the challenge goes. However, I argue that some simples (taken together) can collectively instantiate an emergent property, so the nihilist's ontology can in fact accommodate emergent properties. Furthermore, I show that employing plural instantiation does not bloat the nihilist's ontology or ideology.     

How Superduper Does a Physicalist Supervenience Need to Be?

The standard formulations of the supervenience relation present the supervenience of one set of properties on another in terms of property correlations, without placing any constraints on the dependency relation concerned. This does not ensure that properties supervening upon phys-icalistically acceptable base properties are not themselves emergent in a way at odds with materialism. So physicalism needs 'superdupervenience'. I argue that, where supervenient and base properties are instantiated in the same individuals, Horgan's requirement of robust explanation is neither sufficient nor necessary for superdupervenience. His paradigm case is compatible with the supervenient property's being emergent. This and other unacceptable possibilities may be ruled out by means of a metaphysical constraint on the supervenience relation, which must be internal. Each individual causal power in the set associated with a given supervenient property must be numerically identical with a causal power in the set associated with its base property. Satisfying this condition is all that is needed to render supervenience superduper. In fact a wide variety of non-reductive physicalist accounts are implicitly or explicitly designed to meet this condition, and so are more similar than they seem.     

Diachronic Emergence and Its Characteristics from the Viewpoint of Complexity Science

Complexity science, which arose in the second half of the 20th century, initiated research into the emergence of complex systems and led to the rise of the concept of diachronic emergence. Compared to British emergentism, research on diachronic emergence underwent some crucial changes—namely, (1) putting the enterprise of unveiling the mechanics of emergence at its core; (2) taking inter-disciplinary research as its viewpoint; (3) and taking computer simulation as its method. Because of this new approach, “diachronic emergence” is closely related to terms from complexity science such as “systems,” “self-organization,” “complexity,” and “chaos.” In this paper, we examine two cases of purported diachronic emergence and argue that both count as genuine cases of ontological emergence. The first is Paul Humphreys’ fusion emergence and the second is Mark Bedau’s simulation emergence. In both cases, the emergent entity/property possesses genuine causal powers, and hence counts as a form of ontological, not merely epistemological emergence. Fusion emergence is a kind of strong diachronic emergence that emphasizes diachronicity and non-supervenience. The kind of emergence based on computer simulations can be seen as a kind of weak diachronic emergence. Bedau studies the process and mechanics of emergence with the help of computer simulations, and he argues that weak diachronic emergence has characteristics such as underivability without simulation, explanatory incompressibility, and underivability without crawling the micro-causal web. Moreover, he tries to present an explanatory model of weak emergence that posits the existence of higher-level entities with weak downward causation and claims the emergent level to be explanatorily autonomous. The core of both strong diachronic emergence and weak diachronic emergence is a focus on unpredictable emergent entities, which are new properties or new structures generated from evolution, and a characteristic emphasis on the diachronicity of the generation of emergent entities. Therefore, diachronic emergence has characteristics such as novelty in evolution, unpredictability, and autonomy of macro-explanation.     

A NEW PROBLEM FOR ONTOLOGICAL EMERGENCE

It is becoming increasingly common to find phenomena described as emergent. There are two sorts of philosophical analysis of emergence. Ontological analyses ground emergence in real, distinct, emergent properties. Epistemological analyses deny emergent properties and stress instead facts about our epistemic status. I review a standard worry for ontological analyses of emergence, that they entail a surfeit of metaphysics, and find that it can easily be sidestepped. I go on to present a new worry, that ontological emergentism entails a highly implausible ontology, which is harder for the ontological emergentist to avoid.     

Formulating physicalism: Two suggestions

Two ways are considered of formulating a version of retentive physicalism, the view that in some important sense everything is physical, even though there do exist properties, e.g. higher-level scientific ones, which cannot be type-identified with physical properties. The first way makes use of disjunction, but is rejected on the grounds that the results yield claims that are either false or insufficiently materialist. The second way, realisation physicalism, appeals to the correlative notions of a functional property and its realisation, and states, roughly, that any actual property whatsoever is either itself a physical property or else is, ultimately, realised by instances of physical properties. Realisation physicalism is distinctive since it makes no claims of identity whatsoever, and involves no appeal to the dubious concept of supervenience. After an attempt to formulate realisation physicalism more precisely, I explore a way in which, in principle, we could obtain evidence of its truth.     

Physicalism and the sortalist conception of objects

Many hold an Aristotelian metaphysic of objects: fundamentally, objects fall under sortals and have persistence conditions befitting their sort. Though sometimes offered as a theory of material objects, I argue this view is in fact incompatible with physicalism. Call a ‘sortal’ a kind of object, a ‘sortal identity’ a particular’s nature specified in sortal terms, and ‘sortal properties’ properties that are determined by an object’s sortal identity, such as its persistence conditions. From here the argument runs as follows. Something is physical only if it is physically fundamental or is determined by what is physically fundamental (P1), but sortal identities and properties are neither physically fundamental (P2) nor determined by the physically fundamental (P3). I defend each premise in turn. P1 falls out of the standard conception of physicalism. Rejecting P2 is tantamount to positing Aristotelian substantial forms and formal causes—which are themselves incompatible with physicalism. I defend P3 by showing that extant solutions to “the grounding problem”—the problem of showing how (nonfundamental) sortal properties are determined by (nonsortal) physical properties—are either physicalistically unacceptable, or else physicalistically acceptable but opposed to the sortalist metaphysic.     

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.     

The Relativity Of Color

C. L. Hardin led a recent development in the philosophical literature on color in which research from visual science is used to argue that colors are not properties of physical objects, but rather are mental processes. I defend J. J. C. Smart's physicalism, which claims that colors are physical properties of objects, against this attack. Assuming that every object has a single veridical (that is, nonillusory) color, it seems that physicalism must give a specification of veridical color in terms natural to physics, independently of our interests. Hardin argues that since physicalism doesn't give us any such specification of veridical color, this view is false. However, this argument assumes a mistaken account of veridical color. I show physicalism can appeal to an alternative account, according to which veridical color is characterized in terms of favored conditions of perceptual access, independently of any specification of the physical nature of color.     

Do a Posteriori Physicalists Get Our Phenomenal Concepts Wrong?

A posteriori physicalism is the combination of two appealing views: physicalism (i.e. the view that all facts are either physical or entailed by the physical), and conceptual dualism (i.e. the view that phenomenal truths are not entailed a priori by physical truths). Recently, some philosophers such as Goff (2011), Levine (2007) and Nida‐Rümelin (2007), among others, have suggested that a posteriori physicalism cannot explain how phenomenal concepts can reveal the nature of phenomenal properties. In this paper, I wish to defend a posteriori physicalism from this new and interesting challenge, by arguing that a posteriori physicalists have the resources to explain how phenomenal concepts can reveal at least something of what it would take for the corresponding phenomenal property to be instantiated.     

Problems with the ‘physical’ in physicalism

Hempel's Dilemma is a challenge that has to be met by any formulation of physicalism that specifies the physical by reference to a particular physical theory. It poses the problem that if one's specification of the physical is ‘current’ physical theory, then the physicalism which depends on it is false because current physics is false; and if the specification of the physical is a future or an ideal physics, the physicalism based on it would be trivial as it would be tautologously true, or because very little (if anything at all) can be inferred from or about a physics that does not yet exist. I review the reasons for thinking that the dilemma is a perpetual problem for currentist specifications of the physical, then introduce the argument that the standard positions on the specification question are wanting because they lack a generality which physicalism is generally accepted to have. I end with a suggestion for a way forward for physicalism.     

Realization and the metaphysics of mind1

According to a familiar view in philosophy of mind, mental states or properties are realized by physical states or properties but are not identical to them. This view is often called realization physicalism. But what is realization? I argue that recent approaches to realization, represented by Carl Gillett's ‘dimensioned’ view, fail to acknowledge some textbook cases of realization. I also argue Gillett's account in particular admits realization relations that should not count if realization physicalism is to be distinguished from its competitors in the usual ways. I offer my own account of realization, and argue that it is superior not only in passing the above tests but also in its utility for answering questions about multiple realizability.     

Grounding,physicalism and necessity

Recent work on metaphysical grounding has suggested that physicalism can be characterised in terms of the mental facts being grounded in physical facts. It is often assumed that the full grounds of a fact metaphysically necessitate that fact. Therefore, it seems that if the physical grounds the mental, then the physical facts metaphysically necessitate the mental facts. Stefan Leuenberger argues that such a version of physicalism would be vulnerable to counterexamples. I shall outline a characterisation of grounding which appeals to a relation between grounding and the essences of properties instantiated in the grounded facts or in their grounds. If a grounded fact is such that its constituent property is essentially related to the properties instantiated in its grounds, or vice versa, then the grounded fact will be metaphysically necessitated by its full grounds. This characterisation of grounding not only avoids Leuenberger’s counterexamples, but has broader implications for characterising physicalism in terms of grounding.