‘If mental causes were not physical, they would be epiphenomenal.’ Discuss.
The quote in the essay title is the ending conclusion of a longer argument on the relationship between the mind (or mental phenomena) and the body (or physical phenomena). To establish the context within which this argument functions, I must say a few words introducing the approaches to the “Mind-Body Problem” that appear in the Philosophy of Mind. These approaches fall into three groups:
(i) there are “Dualist” approaches that argue that the Mind (or mental phenomena, properties, events, causes) are in some separate world from the Body (or physical phenomena, properties, events, causes). The most famous advocate of Dualism was Rene Descartes(1). No one these days argues for his “substance dualism”. But the modern version is “property dualism” — the theory that mental properties are completely separate, non-reducible to, and not understandable in terms of, whatever physical properties underlie them. One modern advocate of this theory is Colin McGinn(2).
(ii) there are “Idealist Monist” approaches that argue that all that exists is Mind, and that what we conceive of as the Body (or physical phenomena, properties, events) is but a figment, or echo, or construct of some Mind. The most famous advocate of this approach was George Berkeley(3). A modern version of this theory is the Pantheism argued for by the theologian Huw Owen(4).
(iii) and then there are the “Materialist/Physicalist Monist” approaches that argue that all that exists is the Body (or physical phenomena, properties, events, causes) and that what we conceive of as the Mind (or mental phenomena, properties, events, causes) is but a different view or description or conception of what is at base physical phenomena. Exact details of that relationship vary by philosopher. But despite that variation, Physicalism is the currently standard approach in the Philosophy of Mind(5).
One of the problems in interpreting the meaning intended by the titled quote, is the debate over just what constitutes “physical”. Although the intuitive notion is that what constitutes the “physical” is only those things that are studied by the material sciences, as outlined by McDowell(6) and Stoljar(7), there is a great deal of debate over the details of just how to specify that notion. For the purposes of this essay, however, I’ll leave the notion at the intuitive level.
Another area of dispute affecting an understanding of the titled quote, is the concept of a “mental cause”. As Terence Horgan explains, contra Davidson’s conception of causation,
“causal explanation is a highly context relative, highly interest relative affair, and attention to numerous examples . . . makes clear the implausibility of insisting that the only properties of a cause and effect that are relevant to causal explanation are ones which figure in a ‘strict law’.”(8)
As with the detailed specification of “physical”, there is significant debate over the concept of a “cause”. Ideas range from the “association of ideas” of David Hume(9) to the transfer of energy and conservation of key quantities of Messrs. Fair, Salmon, and Dowe(10). The disputes center on just how a “mental cause” ought to be conceived, and how it achieves its effects (if any). Causes supposedly have their effects in virtue of their properties. So are the mental properties of mental causes responsible for their physical effects? And if so, how? Again, for the purposes of this essay, I’ll leave the notion of a “mental cause” at an intuitive level.
A key premise adopted within most of the various Physicalist approaches is the assumption of “Causal Closure of the Physical”. This premise states: “No physical event has a cause outside the physical domain.” – Jaegwon Kim(11). Now since Physicalism assumes both that mental phenomena are (in some specified way) physical phenomena, and that causal closure stipulates that all physical phenomena have only physical causes, the quote in the essay title argues that if mental causes are not physical, then they would have no physical effects — in other word, they would be epiphenomenal.
Unfortunately, the argument suffers from a few serious defects. The first is that it relies on the premise of causal closure. Assuming causal closure stipulates that mental causes cannot have physical effects. Hence the argument commits the fallacy of begging the question. Obviously, if mental causes are not physical, they would be “non-physical” (i.e. “mental”). And, ex hypothesi, “mental” causes cannot cause physical effects.
Secondly, the argument is self-contradictory. If “mental” causes are admitted to truly cause physical phenomena, then they would not be epiphenomenal, but physicalism would be false. The only way to maintain the sense of the argument in the title quote is to conceive of “mental causes” as something separate from, over and above, or otherwise beyond, the physical. But that is either applying a dualist intuition to a physicalist base, contradicting the very notion of physicalism, or it is denying physicalism, in which case it does not follow that “mental” causes would be epiphenomenal.
What a number of philosophers have resorted to is a view of mental phenomena (and mental causes) as supervenient in some way on the physical. (There are several different versions of the notion of this “supervenient” relation that have been defined in the philosophical literature(11.5).) This allows the ontology to remain thoroughly physicalist, but provides for non-physical mental phenomena. Given this conception, what does mental causation consist in, if mental phenomena are supervenient on the physical? Given the assumption of causal closure of the physical, it is this question that causes the argument in the essay title. Conceiving mental phenomena as different from, but supervening on physical phenomena, allows an opening for mental causes that do not cause any physical effects — hence epiphenomenal.
A number of philosophers have approached the problem from this perspective. For example, Time Crane and Bill Brewer(12), Nick Zangwill(13), Douglas Ehring(14), and John Gibbons(15) have outlined various interpretations of a supervening relationship between mental phenomena (mental causation) and the underlying physical phenomena (physical causation) that makes it questionable whether “mental causes” should be considered efficacious or epiphenomenal. Jaegwon Kim(16) has described a concept of “supervenient causation” that supposedly allows a mental cause as a supervening entity, to cause both other mental phenomena as well as physical phenomena, by way of a special notion of causation. A notion he strictly separates from the “regular” notion of physical causation. But all these philosophers seem to view mental phenomena as different from physical phenomena (either as objects/entities, properties, or events), so they have trouble explaining just how mental causes can be effective — and not be epiphenomenal.
Other philosophers, such as Daniel Dennett(17), Stephen Yablo(18), and Crawford Elder(19) view the underlying “supervenience” relationship between the mental and the physical as being some sort of realizing or constitutive relationship — even though many of them still use the term “supervenient” to describe it. On this view of mental causes, they simply are physical causes — albeit differently described or conceived. Since, on this view, mental causes are physical in an unproblematic sense, there is no need to consider them as epiphenomenal. And no need for Kim’s “supervenient causation”.
There is no debate that, say, Quantum Mechanics and Relativity Theory supervene (in some fashion) on String Theory. And there is no difficulty in granting full effective physical causality to the photon that mediates the repulsion of two converging electrons. Even though, in String Theory, all of this must be expressed in the equations of vibrating energy branes. There is, similarly, no debate that the electric charges of electrons and protons of the constituting atoms is fully effective in physically causing the complex folding of a protein molecule. Likewise, there is no debate that the interplay of complex chemical molecules constitutes the dynamic process that we call life (fans of elan vital aside). That the heart attack caused the subject’s death is an unproblematic use of physical causation. All potential debate is adequate defused because we can imagine, and thus understand, the processes (or kinds of processes) involved — to some degree, if not fully.
The debate only arises when we try to understand how the complex dynamic processes of life can give rise to the first-person subjective self-referencing “feels-like” experience of consciousness. We have more than adequate grounds, from the rest of science, to accept a Physicalist position for every other area of experience except these first-person, “feels-like” phenomena. The only reason not to extend that Physicalist position to include mental phenomena (and mental causes) would be a lack of imagination about the possible processes involved. The third of the problems inherent in the title quote, therefore, is that it commits the fallacy of incredulity by allowing the possibility that mental causes could not be physical.
All of this yields two possibilities, either
(i) physicalism is true, and mental causes cannot ex hypothesi be non physical (rendering the first part of the conditional false and the conditional trivially true), or
(ii) physicalism is false, the causal closure principle is not operable, and mental causes can be efficacious rather than epiphenomenal. The consequent of the argument does not follow from the antecedent.
In either case, the quoted title argument is simply wrong.
Notes & References
(1) Descartes, Rene; excerpt from Meditations on First Philosophy (Bk II & VI) in Chalmers, David J. (ed.); Philosophy of Mind: Classical and Contemporary Readings, Oxford University Press, Oxford, England, 2002, ISBN 978-0-19-514581-6. Pp 10-20.
(2) McGinn, Colin; The Character of Mind: An Introduction to the Philosophy of Mind, 2nd Edition, Oxford University Press, Oxford, England, 1982, ISBN 978-0-19-875208-0.
(3) Berkeley, George; excerpt from The Principles of Human Knowledge in Beakley, Brian & Ludlow, Peter (ed.); The Philosophy of Mind: Classical Problems / Contemporary Issues, 2nd Edition, The MIT Press, Cambridge, Massachusetts, 2006, ISBN 0-262-52451-1. Pp 31-34.
(4) Owen, Huw Parri; Concepts of Deity, Herder and Herder, Crossroads Publishing Company, New York, New York, 1971, ISBN 978-0-3330-1342-7.
(5) Wikipedia contributors; “Physicalism” in Wikipedia, The Free Encyclopedia. URL=<http://en.wikipedia.org/w/index.php?title=Physicalism&oldid=511083913>.
(6) Dowell, J.L.; “Formulating the Thesis of Physicalism: An Introduction” in Philosophical Studies: An International Journal of Philosophy in the Analytic Tradition, Vol 131, No 1 (Oct 2006), pp 1-23, URL=http://www.jstor.org/stable/25471797
(7) Stoljar, Daniel; “Physicalism” in The Stanford Encyclopedia of Philosophy (Fall 2009 Edition), Edward N. Zalta (ed.), URL=http://plato.stanford.edu/archives/fall2009/entries/physicalism/
(8) Horgan, Terence; “Mental Quasation” in Philosophical Perspectives, Vol 3, Philosophy of Mind and Action Theory (1989), pp 47-76. URL=http://www.jstor.org/stable/2214263
(9) Hume, David, A Treatise of Human Nature 2nd Edition, L. A. Selby-Bigge (ed.) revised by P.H. Nidditch, Clarendon Press, Oxford, England, 1975. Pg 108
“For finding, with this system of perceptions there is another connected by custom, or, if you will, by the relation of cause and effect, it proceeds to the consideration of their ideas; and as it feels that ’tis in a manner necessarily determin’d to view these particular ideas, and that the custom or relation, by which it is determin’d, admits not of the least change, it forms them into a new system, which it likewise dignifies with the title of realities. The first of these systems is the object of the memory and senses; the second of the judgment.”
(10) Dowe, Phil, “Causal Processes” in The Stanford Encyclopedia of Philosophy (Fall 2008 Edition), Edward N. Zalta (ed.), URL=http://plato.stanford.edu/archives/fall2008/entries/causation-process/
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