Physicalism And Alternatives Research Paper

1. Physicalism

1.1 Formulating Physicalism

So-called type physicalism is the doctrine that every type or kind of thing is physical. Physicalists need not be committed to type physicalism. Many physicalists allow that some kinds of things are such that is logically possible for them to have instances in, for instance, a spiritual realm that is wholly devoid of matter. For example, it seems logically possible for certain kinds of social institutions and social contracts to have instances in such a spiritual realm. Physicalists insist only that in reality, that is, in the world as it actually is (i.e., in the actual world), any instance of any kind of thing, including any kind of social institution or social contract, is at some level of composition, wholly composed of physical entities (Hellman and Thompson 1975).

Given that being wholly composed of physical entities suffices for being physical, physicalism implies token physicalism for objects, the thesis that every object that is physical. Physicalism is not, however, equivalent to this thesis. One reason is that even if every object is physical, it might be an accident that this is so, for there might be laws of nature according to which, were certain physical conditions to obtain, wholly disembodied spirits would come into existence. That is, the laws of nature might be such that a certain brew of physical ingredients would bring into existence wholly disembodied spirits, even though, by chance, the physical ingredients in question have never come together into that brew (Witmer 1997). Since physicalists deny that there are such laws it is too weak to formulate physicalism as token physicalism for objects. Another reason it is too weak is that token physicalism for objects is compatible with there being properties whose actual patterns of distribution over objects fail to be determined by physical laws and the pattern of distribution of physical properties, and, according to physicalists, the pattern of distribution of every property is so determined.

It would be too strong, however, to formulate physicalism in a way that implies that all properties are physical properties, for physicalists typically allow that there are functional properties. A functional property is a second-order property: it is the property of having some property or other that occupies a certain lawful or counterfactual role (Putnam 1967, Block 1994). Functional properties are realized by the first-order properties that occupy the roles in question. (A functional property may be multiply realizable in that there may be more than one first-order property that can occupy the relevant role.) Many functional properties are such that it is logically possible for them to be realized by nonphysical properties, which is why they themselves do not count as physical properties. Physicalists claim, however, that physical laws and physical conditions determine what functional properties there actually are, and that, in actuality, functional properties are ultimately realizable only by physical properties. And they claim further that physical laws and physical states and events determine the occurrence of every state or event that is an instance of a functional property. Since nonphysical properties and kinds may be cited in laws of the special sciences, it would also be too strong to formulate physicalism in a way that implies that all laws are physical laws. Physicalists maintain only that all fundamental laws are physical laws, that nonphysical laws are determined by physical laws and physical conditions.

Still, physicalism is first and foremost a thesis about what there actually is. It is the thesis that all there actually is is whatever there has to be given the way the actual world is in every physical respect—in respect of what physical objects there are, what physical properties they have, what physical relations they bear to other physical objects, what physical laws govern their behavior, etc. Physicalism can allow that there are actual nonphysical kinds of objects, nonphysical properties, relations, laws, etc., provided that they must exist, given the way the actual world is physically. What physicalism disallows is that the actual world contains anything that is unnecessary for it to be exactly as it is physically.

Call any possible world (i.e., any way the world might be) that is exactly like the actual world in every physical respect, a physical duplicate of the actual world. It is, of course, trivial that the actual world is a physical duplicate of itself. Call any possible world that is a physical duplicate of the actual world and that contains nothing other than what is required to be a physical duplicate of the actual world, a minimal physical duplicate of it. It is by no means trivial that the actual world is a minimal physical duplicate of itself. For this claim has, for instance, the consequence that there are actually people, shopping malls, cities, and countries only if there have to be people, shopping malls, cities, and countries in order for the actual world to be a physical duplicate of itself. Physicalism is equivalent to the controversial thesis that the actual world is a minimal physical duplicate of itself.

Call any possible world that is exactly like the actual world in every respect whatsoever, physical or otherwise, a duplicate simpliciter of it. A possible world could be a physical duplicate of the actual world without being a duplicate simpliciter of it. For there is nothing about the way the actual world is in physical respects that excludes there being, say, a realm of disembodied spirits, provided that this spiritual realm exerts no causal influence on the physical. Physicalism, however, disallows that there are such ‘extra entities’ in the actual world. Physicalism is equivalent to the following thesis: any minimal physical duplicate of the actual world is a duplicate simpliciter of the actual world (Jackson 1998). That is to say, all that there actually is is whatever there has to be given the way the actual world is physically if and only if any minimal physical duplicate of the actual world is a duplicate simpliciter of it.

The idea that any minimal physical duplicate of the actual world is a duplicate simpliciter of it can be vividly illustrated by a creation myth. Suppose that Mother Nature wanted to create an exact duplicate of the actual world. According to physicalism, then, all that She would have to do is create an exact physical duplicate of the actual world—a world exactly like it in every physical respect. Her work would then be done. She would have thereby created a world exactly like the actual world in every respect whatsoever.

1.2 The Term ‘Physical’

What is meant by ‘physical’ in the phrase ‘the way the actual world is in every physical respect’? The relevant notion of physicality is tied to physics. There is, however, a dilemma that any attempt to state the tie must face (Hempel 1969, Crane and Mellor 1990). The dilemma can be formulated thus: if by ‘the way the actual world is in every physical respect’ is meant the way current physics says the world is (in respect of what objects there are, what properties they have, etc.), then physicalism is no doubt false, for current physics is no doubt false. On the other hand, if by ‘the way the actual world is in every physical respect’ is meant the way the true, complete physics would say the world is, then physicalism is either trivially true or too obscure to be a subject of rational assessment.

While current physics is a vast improvement over any previous physics, it is, nonetheless, no doubt false. The first horn of the dilemma should thus be avoided. What, then, of the second horn? If the second horn were embraced, then it would be trivially true that the way the world is in every physical respect is the way the true, completed physics would say that it is, for the claim would be true by definition. It would not follow, however, that physicalism is true by definition, or even that it is trivially true. For were ‘the way the actual world is in every physical respect’ to be understood in this way, then physicalism would be the thesis that all that there actually is is whatever there has to be for the actual world to be the way the true, complete physics says that it is. That thesis is by no means trivial. The true, complete physics would not, for instance, postulate a spiritual realm that is causally isolated from the realm governed by its laws. (Even if, contra physicalism, the true, complete theory of the actual world would postulate such realm, the part that counts as physics would not.) Yet it is by no means trivially true that there is no such realm.

Still physicalists do not maintain that ‘the way the actual world is in every physical respect’ means the way the true, complete physics would say the world is. For the true, complete physics might postulate phenomena that physicalists deny actually exist. Mechanics, the theory of motion, is a central branch of physics. A true, complete physics would thus include a true, complete mechanics. A true, complete mechanics would take into account all of the fundamental causes of motion. Suppose, then, that the actual world contains Cartesian minds, substances that are not extended in space, but that occupy intrinsic, conscious states that exert a fundamental causal influence on the motions of particles in the brains of human beings, and, thereby, a fundamental causal influence on the behavior of human beings. If so, then the true, complete physics would be a Cartesian-like physics in that it would postulate Cartesian minds. But were this the case, physicalist would regard physicalism as false. It may well seem preposterous that the true, complete physics is a Cartesian-like physics. Current physics is surely not that badly wrong. The point, however, is that it is not true by definition that the true, complete physics is not a Cartesian-like physics.

Physicalists indeed claim that the way the actual world is in every physical respect is the way the true, complete physics would say that it is. But this is not intended to be true by definition. Physicalists make the claim because they are betting that the true, complete physics will share certain features with current physics (Pettit 1993). Call any theory of physics that is an improvement over current physics and that retains the features in question (whatever they are), a successor physics to current physics. The physicalist is betting that the true, complete physics will be a successor physics to current physics. By ‘the way the actual world is in every physical respect’ physicalists mean the way that the true, complete successor physics to current physics says the world is. And thus physicalism is the thesis that all there actually is is whatever that has to be given the way the true, complete successor physics to current physics says that the actual world is. To steer a course between the horns of the dilemma, physicalists must identify the features that a theory of physics must share with current physics to count as a successor to it.

The place to look to discern the features in question is at the advances in physics and the special sciences of chemistry and biology that physicalists maintain lend support to physicalism. At the start of the twentieth century, not all chemical theorists accepted atomism, and even some atomists speculated that the explanation of chemical bonding might have to invoke fundamental chemical forces. By the middle of the first decade, however, Einstein’s work on Brownian motion convinced the entire community of chemical theorists of the truth of atomism. Then, after two decades of work on the structure of the atom, quantum mechanics was proposed. Quantum mechanics provides a reductive explanation of chemical bonding that invokes no forces or energies other than those at work below the level of composition of the atom. For a time after the advent of quantum mechanics, there remained speculation that there may be a fundamental, emergent force at work in living organism, a vital elan; but with the advances of molecular biology, such as the discovery of DNA, this idea was abandoned. On the evidence, living things are wholly composed of subatomic entities (such as electrons, quarks, etc.), entities whose behavior is determined by forces and energies exerted below the level of the atom. Biological processes are wholly implemented by chemical processes, which, in turn, are wholly implemented by quantum mechanical ones (McLaughlin 1999a).

Physicalists are not committed to the truth of the whole of current physics, or even to the truth of quantum mechanics. They are, however, betting that the true, complete physics will share the following features with current physics: (a) every entity postulated by the theory will either be subatomic or, at some level of composition, wholly made up of subatomic entities; and (b) the theory will postulate no fundamental forces or energies that are not exerted below the level of the atom. Many physicalists hold that to count as a successor to current physics a physics must retain features (a) and (b). These physicalists allow for the discovery of new objects, properties, forces, fields, and laws, provided that these discoveries are consistent with (a) and (b). They maintain only that the true, complete physics will retain features (a) and (b).

Some physicalists, however, hold a more relaxed view of what features a theory of physics would have to have to be a successor to current physics. Some allow that a fundamentally new kind of macroscopic matter could be discovered that is not composed of subatomic entities, so long as all living things and everything with mental capacities is wholly composed of subatomic entities. Moreover, some physicalists allow for the discovery of emergent forces at work in living things and beings with mental capacities, so long as the forces in question are generated by spatiotemporal configurations of subatomic entities. It is logically possible that when atoms becomes so configured as to compose a cell or so configured as to compose a human brain in a certain of neural state, a fundamental force comes into play that is not exerted by matter at lower levels of complexity. Such emergent forces would exert a fundamental ‘downward’ influence on the behavior of particles (Broad 1925, McLaughlin 1999a). They are ruled out by condition (b). But some physicalists allow that a successor physics to current physics could countenance such emergent forces since they would be generated by spatio-temporal configurations of atoms, and so not, for instance, by states of an entelechy or by ontologically fundamental acts of will.

Stronger and weaker notions of what counts as a successor physics to current physics can thus be distinguished, and with them stronger and weaker versions of physicalism. But even the weakest notion(s) of what counts as a successor physics to current physics would, for instance, exclude a Cartesian-like physics from so counting. The notions of a successor physics to current physics that are invoked to characterize versions of physicalism are vague since it is, for instance, somewhat vague what counts as physics. But they are not so obscure as to render any of the varieties of physicalism outside the realm of rational assessment. (The differences between the stronger and weaker versions of physicalism will not matter for what remains, and so will be ignored.)

Physicalism implies that there is a true, complete successor physics to current physics, but it is not equivalent to that claim. Nonphysicalists can accept that there is a true, complete successor physics to current physics, in even the strongest sense. Indeed, nonphysicalists can even allow that current physics may be true. For physicalism says more than that the actual world is the way that the true, complete successor physics to current physics says that it is. Physicalism is the thesis that all there actually is is whatever there has to be given the way that the true, complete successor physics to current physics says that the world is. It is this claim that nonphysicalists deny.

2. Whether Physicalism Or One Of Its Alternatives

2.1 The Causal Priority Of The Physical

Physicalism is defended both by appeal to empirical evidence and by appeal to supraempirical considerations of overall coherence and theoretical simplicity.

Physicalists claim that physical determination is true: the objective probability of any physical event or state is wholly determined by prior physical events and states. Thus, the objective probability of the physical movements of any living organism or sentient creature, and any movement of any of its physical parts, will be wholly determined by prior physical events (perhaps those occurring on some cross-section of the backward light-cone of the physical movements in question). Thus, given physical determination, if there are actual nonphysical states or events, then either (a) they do not causally interact with physical occurrences at all, or (b) they causally interact with physical occurrences, but not by means of any underlying causal chain of physical occurrences, or else (c) they causally interact with physical occurrences derivatively, that is, by means of some underlying chain of physical occurrences (McLaughlin 1994).

Physicalists appeal to supraempirical considerations of overall coherence and theoretical simplicity to rule out alternatives (a) and (b). In response to (a), they maintain that there is no need to postulate states or events that have no physical effects in order to explain anything that requires explanation. In response to (b), they maintain that since physical determination is true, this possibility would involve a bizarre kind of autonomous causal over-determination of the physical by the nonphysical that can be ruled out on grounds of theoretical simplicity, and not at the expense of overall coherence (Witmer 1997). Finally, in response to (c), some physicalists argue that only physical events causally interact with physical events. However, some physicalists allow that there are nonphysical events that causally interact with physical events in a derivative way, by means of underlying causal chains of physical occurrences. For they maintain that the nature of the underlying relationship is such that in any minimal physical duplicate of the actual world, the physical occurrences in that world will underlie exactly the same sorts of nonphysical occurrences that their physical counterparts underlie in the actual world, and, so, that (c) is compatible with physicalism.

Few philosophers now challenge physical causal determination, most accept the thesis on the evidence. To answer supraempirical considerations for physicalism, nonphysicalists typically argue that there are reasons to accept that there are certain actual phenomena not countenanced by physicalism, and that those reasons outweigh the consideration that the phenomena would be either epiphenomena or autonomous overdeterminers of certain physical occurrences.

2.2 Elimination Or Entailment?

According to physicalists, all that there actually is is whatever there has to be given the way the actual world is physically. When it is claimed that a certain phenomenon actually exists that is not required for the actual world to be exactly as it is physically, physicalists have two options. They can argue that there is no phenomenon of the sort in question, and thus be eliminativists or irrealists about it. (All physicalists are eliminativists about disembodied spirits, for instance.) Or they can argue that, despite first appearances, the phenomenon in question must exist given the way the actual world is physically.

The debate between physicalists and nonphysicalists is mainly centered on the mental and on phenomena logically dependent on the mental. Some physicalists are eliminativists about the mental, or at least about the mental as conceived by folk or commonsense psychology (Churchland 1978, Stich 1999). But most physicalists are realists about the mental, and many are realists about the moral also, and attempt to explain moral properties reductively, in part, by appeal to mental properties.

Physicalists argue that a phenomenon must exist given the way the actual world is physically by arguing that it is plausible that its existence is entailed by the totality of physical facts (Jackson 1998). The totality of physical facts includes all particular physical facts and all general ones, including all nomological ones, and includes as well a ‘that’s all’ physical fact, a fact to the effect that the physical facts in question are all the physical facts.

Given physicalism, the totality of physical facts, in conjunction with the contingent thesis of physicalism, entails all of the facts. Thus, if, for example, it is a fact that a certain property has a certain worldwide pattern of distribution, then the totality of physical facts in conjunction with the thesis of physicalism will imply that the property has that worldwide pattern of distribution. The totality of physical facts will, of course, imply facts about the actual worldwide pattern of distribution of physical properties. The totality of physical facts, in conjunction with the assumption of physicalism, will imply facts about the actual worldwide pattern of distribution of functional properties and any properties metaphysically necessitated by physical properties, and will imply as well that no other sorts of properties are actually possessed by anything.

One way to establish that mental facts are entailed by the totality of physical facts and the truth of physicalism alone is by showing that the relevant mental concepts are definable in terms of physical and topic-neutral concepts (Smart 1959). (Topic-neutral concepts are neither physical nor mental concepts; they include the concept of a part, the concept of causation, and logical concepts such as the concept of conjunction, the concept of negation, and the concept of universal quantification.) Both analytical behaviorism and analytical functionalism entail that there are such definitions. According to analytical behaviorism, mental concepts can be defined in terms of concepts of dispositions to peripheral behavior (Byrne 1994). According to analytical functionalism, mental concepts can be defined more broadly in terms of macrophysical and topic-neutral concepts (Armstrong 1968, Block 1994, Lycan 1994).

Analytical behaviorism is widely regarded as a failed project. It is now generally acknowledged that no mental concept can be defined in terms of concepts of dispositions to peripheral behavior. Analytical functionalism continues to have proponents (Lewis 1994), but it is controversial whether it is true of any mental concept. Analytical functionalism is most plausible for intentional concepts such as the concepts of belief, desire, intention, and the like, since these concepts are, arguably, dispositonal concepts. But it is especially controversial whether analytical functionalism is true of sensory (or phenomenal) concepts such as the concept of the felt quality of pain (Block 1995, Chalmers 1996). Many philosophers, both physicalists and nonphysicalists, claim that sensory concepts fail to have a priori functional analyses of any sort. They maintain that there is an explanatory gap between sensory concepts and physical and topic neutral concepts in that sensory concepts are neither definable in terms of such concepts nor are their references fixed by associated physical and topic neutral concepts (Levine 1983).

Scientific functionalism and type materialism are physicalist alternatives to these a priori approaches to explaining how mental facts are entailed by the totality of physical facts and the assumption of physicalism. To focus for illustration on the case of pain, scientific functionalism maintains that pain is identical with a type of functional state (and, so, a type of secondorder state), albeit the identity is knowable only a posteriori (Loar 1997). Type materialism maintains that pain is identical with a type of abstract neurobiological state, and that the identity is knowable only a posteriori (Hill 1991). As Saul Kripke (1980) has demonstrated, identity statements in which the identity sign is flanked by rigid designators (terms that have the same reference in any world in which they refer) are either necessarily true or necessarily false, even if only a posteriori. ‘Pain’ is a rigid designator; it is the name of a certain kind of sensation. Statements asserting that pain is identical with a certain type of functional state or ones asserting that pain is identical with a certain type of neurobiolgical state will be necessarily true, if true at all. Given the necessity of identity, if pain is identical with either a type of functional state or a type of macrophysical state, then facts about the pattern of realization of the functional state or macrophysical state in question will imply facts about the pattern of realization of pain. Thus if, for instance, pain neurobiological state N, then facts about the worldwide distribution of N-states will entail facts about the worldwide distribution of pain (and conversely). According to type materialists, the entailments will be only a posteriori. Scientific functionalists make an analogous claim of a posteriori entailment.

Some philosophers argue that physicalism must be committed to the a priori entailment of all the facts (save indexical ones such as, e.g., I = Brian McLaughlin) from the totality of physical facts and the assumption of physicalism, on pain of being committed to an unacceptable view of necessity and/or an unacceptable view of conceptual reference (Chalmers 1996, Jackson 1998). Also, some of these philosophers argue that since facts about sensory consciousness will not be a priori entailed by the totality of physical facts and the assumption of physicalism, physicalism is false. Scientific functionalists and type materialists agree that facts about sensory consciousness are not so a priori entailed, but they reject the claim that the entailments must be a priori. They argue that while sensory concepts are not a priori linked to physical or functional concepts, and so do not admit of a priori functional analyses of any sort, sensory concepts nonetheless apply solely in virtue of the physical or functional properties to which they refer. Suffice it to note that this dispute turns on unresolved issues about the nature of necessity and the nature of conceptual reference.

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