Epiphenomenalism

Epiphenomenalism is a position in the philosophy of mind according to
which mental states or events are caused by physical states or events
in the brain but do not themselves cause anything. It seems as if our
mental life affects our body, and, via our body, the physical world
surrounding us: it seems that sharp pains make us wince, it seems that
fear makes our heart beat faster, it seems that remembering an
embarrassing situation makes us blush and it seems that the perception
of an old friend makes us smile. In reality, however, these sequences
are the result of causal processes at an underlying physical level:
what makes us wince is not the pain, but the neurophysiological
process which causes the pain; what makes our heart beat faster is not
fear, but the state of our nervous system which causes the fear etc.
According to a famous analogy of Thomas Henry Huxley, the relationship
between mind and brain is like the relationship between the
steam-whistle which accompanies the work of a locomotive engine and
the engine itself: just as the steam-whistle is caused by the engine's
operations but has no causal influence upon it, so too the mental is
caused by the workings of neurophysiological mechanisms but has no
causal influence upon their operation.

1. What Is Epiphenomenalism?

In the beginning epiphenomenalism was known as the doctrine of
"automatism" or as the "conscious automaton theory." The term
"epiphenomenalism" seems to have been introduced in 1890 in William
James's The Principles of Psychology (it occurs once in the chapter
entitled "The Automaton-Theory;" other than that James uses the terms
"automaton-theory" or "conscious automaton-theory;" see Robinson
2003). The term "epiphenomenon" was used in medicine in the late
nineteenth century as a label for a symptom concurrent with, but not
causally contributory to, a disease (an epiphenomenon is thus
something like a secondary symptom, a mere afterglow of real
phenomena). Accordingly, epiphenomenalism in the philosophy of mind
holds that our actions have purely physical causes (neurophysiological
changes in the brain, say), while our intention, desire or volition to
act does not cause our actions but is itself caused by the physical
causes of our actions. To assume that regular successions of mental
and physical events—volitions followed by appropriate behavior, fear
followed by an increased heart rate, pains followed by wincings
etc.—reflect causal processes is to commit the fallacy of post hoc,
propter hoc: "The soul stands related to the body as the bell of a
clock to the works, and consciousness answers to the sound which the
bell gives out when it is struck" (Huxley 1874, 242).
2. Epiphenomenalism in the 18th and 19th Century

One of the first explicit formulations of epiphenomenalism can be
found in the Essai de Psychologie of the Swiss naturalist and
philosophical writer Charles Bonnet, dating from 1755: "the soul is a
mere spectator of the movements of its body; [...] the latter performs
of itself all that series of actions which constitutes life; [...] it
moves of itself; [...] it is the body alone which reproduces ideas,
compares and arranges them; which forms reasonings, imagines and
executes plans of all kinds, etc." (Bonnet 1755, 91). More than a
century later, the British philosopher Shadworth Hodgson also
expressed the view that "[s]tates of consciousness are not produced by
previous states of consciousness, but both are produced by the action
of the brain; and, conversely, there is no ground for saying that
[...] states of consciousness react upon the brain or modify its
action" (Hodgson 1865, part 1, ch. 5, §30). The most prominent
articulation and defense of epiphenomenalism, however, stems from the
Presidential Address to the British Association for the Advancement of
Science of the British biologist, physiologist and philosopher Thomas
Henry Huxley, published in 1874 with the suggestive title "On the
hypothesis that animals are automata, and its history." Huxley argued
that brute animals and (presumably) human beings are conscious
automata: they enjoy a conscious mental life, but their behavior is
determined solely by physical mechanisms. Huxley was convinced that
the body of humans and animals is a purely physical mechanism and that
the physical processes of life are explainable in the same way as all
other physical phenomena. This mechanistic conception, he held, "has
not only successfully repelled every assault that has been made upon
it, but [...] is now the expressed or implied fundamental proposition
of the whole doctrine of scientific Physiology" (Huxley 1874, 200).
Already Descartes had argued that non-human animals are mere
mechanical automata and subject to the same laws as other unconscious
matter, and Huxley wholeheartedly embraced Descartes's defense of
automatism by appeal to reflex actions (Huxley 1874, 218). Huxley
observed that a frog with certain parts of his brain extracted was
unable to initiate actions but nevertheless able to carry out a range
of reflex-like actions. Since he thought that the partial leucotomy
made sure the frog was totally unconscious, he concluded that
consciousness was not necessary for the execution of reflex actions:

The frog walks, hops, swims, and goes through his gymnastic
performances quite as well without consciousness, and consequently
without volition, as with it; and, if a frog, in his natural state,
possesses anything corresponding with what we call volition, there is
no reason to think that it is anything but a concomitant of the
molecular changes in the brain which form part of the series involved
in the production of motion. (Huxley 1874, 240)

Huxley agreed with Descartes that animals are automata, but he was
unwilling to accept that they are devoid of mentality: "Sleeping dogs
frequently appear to dream. If they do, it must be admitted that
ideation goes on in them while they are asleep; and, in that case,
there is no reason to doubt that they are conscious" (Huxley 1898,
125). Huxley therefore segregated the question of consciousness from
the question of the status of an automaton: animals do experience
pain, but that pain is, like their bodily movements, just a result of
neurophysiological processes. Animals are conscious automata. In
contrast to Descartes, Huxley argued that considerations similar to
those about reflex actions in frogs also suggest that we are conscious
automata. He referred to a case study of a certain Dr. Mesnet who had
examined a French soldier who had suffered severe brain damage during
the Franco-Prussian war in 1870. From time to time this soldier fell
into a trance-like state in which he was able to execute a series of
complex actions while apparently being unconscious:

If the man happens to be in a place to which he is accustomed, he
walks about as usual; [...] He eats, drinks, smokes, walks about,
dresses and undresses himself, rises and goes to bed at the accustomed
hours. Nevertheless, pins may be run into his body, or strong electric
shocks sent through it, without causing the least indication of pain;
no odorous substance, pleasant or unpleasant, makes the least
impression; he eats and drinks with avidity whatever is offered, and
takes asafœtida, or vinegar, or quinine, as readily as water; no noise
affects him; and light influences him only under certain conditions.
(Huxley 1874, 228)

Since Mesnet's patient could carry out actions ordinarily performed
with consciousness as initiating or coordinating element while
apparently being unconscious, consciousness did not seem to be
necessary for their execution. Since it was impossible to prove that
the patient was indeed unconscious in his abnormal state, Huxley did
not claim to have proven that humans are conscious automata, but he at
least thought that "the case of the frog goes a long way to justify
the assumption that, in the abnormal state, the man is a mere
insensible machine" (Huxley 1874, 235). Huxley's naturalistic or
mechanistic attitude towards the body convinced him that the brain
alone causes behavior. At the same time, his dualism convinced him
that the mental is essentially non-physical. He reconciled these
apparently discordant claims by degrading mentality to the status of
an epiphenomenon.
3. Epiphenomenalism in the 20th Century

Most contemporary philosophers reject substance dualism and the
question that plagued Descartes–How can an immaterial mind whose
nature is to think and a material body whose nature is to be spatially
extended causally interact?–no longer arises. Moreover, many
philosophers even reject Huxley's event-dualism in favor of
psychophysical event-identities. According to one version of
non-reductive physicalism, for instance, every concrete mental event
(every event token) is identical to a concrete physical event,
although there are no one-one correlations between mental and physical
properties (event types). Since fear is identical to the
neurophysiological event which causes the increased heart rate, fear
causes the increased heart rate, too, and epiphenomenalism seems
avoided. However, the charge of epiphenomenalism re-arises in a
different guise. There is a forceful intuition that events cause what
they cause in virtue of some of their properties. Suppose a soprano
sings the word "freedom" at a high pitch and amplitude, causing a
nearby window to shatter. The singing which causes the shattering is
both the singing of a high C and the singing of the word "freedom."
Intuitively, only the former, not the latter, is causally relevant for
the singing's causing the shattering: "Meaningful sounds, if they
occur at the right pitch and amplitude, can shatter glass, but the
fact that the sounds have meaning is irrelevant to their effect. The
glass would shatter if the sounds meant something completely different
or if they meant nothing at all" (Dretske 1989, 1-2). If events cause
their effects in virtue of some of their properties but not in virtue
of others, the question arises whether mental events (even if they are
identical to physical events) cause their effects in virtue of their
mental, their physical or both kinds of properties. If mental events
cause their effects only in virtue of their physical properties, then
their being mental events is causally irrelevant and mental properties
are, in a certain sense, epiphenomena (three reasons for thinking that
mental properties are causally irrelevant are discussed in section
4b). Following Brian McLaughlin, one can thus distinguish between
event- or token-epiphenomenalism on the one hand and property- or
type-epiphenomenalism on the other (see McLaughlin 1989, 1994).
According to the event- or token-epiphenomenalism defended by Huxley,
concrete physical events are causes, but mental events cannot cause
anything. According to the kind of property- or type-epiphenomenalism
that threatens modern non-reductive physicalism, events are causes in
virtue of their physical properties, but no event is a cause in virtue
of its mental properties. If event-epiphenomenalism is wrong, mental
events can be causes; but if they are causes solely in virtue of their
physical properties, property-epiphenomenalism is still true, and some
consider this to be no less disconcerting than Huxley's original
epiphenomenalism (see
4. Arguments for Epiphenomenalism

Arguments in favor of a philosophical theory typically focus on its
advantages compared to other theories—that it can explain more
phenomena or that it provides a more economical or a more unifying
explanation of the relevant phenomena. There are no arguments for
epiphenomenalism in that sense. Epiphenomenalism is just not an
attractive or desirable theory. Rather, it is a theory of last resort
into which people are pushed by the feeling that all the alternatives
are even less plausible. Even epiphenomenalists admit that, from the
first-person point of view of a thinking and feeling subject, they
don't like it. Why, then, do people embrace epiphenomenalism?
a. The No-Gap-Argument

Epiphenomenalism required an intellectual climate in which two
apparently discordant beliefs about the world were equally well
entrenched: a dualism with respect to mind and body on the one hand
and a scientific naturalism or mechanism concerning the body on the
other. To most thinkers of the eighteenth and nineteenth century, it
seemed obvious that human beings enjoy a mental life that resists
incorporation into a purely materialist ontology. Our thoughts,
sensations, desires etc. just seemed to be too dissimilar from
ordinary physical phenomena for them to be "nothing but" physical
phenomena. At the same time, however, science saw the advent of a
decidedly naturalistic attitude towards the human body, motivated by
the successes of mechanistic physics in other areas and characterized
by a desire to identify the underlying causal structure of every
observed phenomenon in terms of matter and motion alone. In
particular, neurophysiological research was unable to reveal any
mental influence upon the brain or the body. Eventually, with the
demise of vitalism regarding the forces governing animate life, the
conception of the physical as a causally closed system, in which
physical forces are the only forces, became almost universally
accepted. When combined with the naturalistic assumption that human
beings are a part of the physical world and governed by its laws, this
left no room for any causal efficacy of our mental life. There simply
seemed to be "no gaps" (McLaughlin 1994, 278) in the causal mechanisms
that could be filled by non-physical phenomena. Therefore,
epiphenomenalism can be regarded as the inevitable result of the
attempt to combine a scientific naturalism with respect to the body
with a dualism with respect to the mind. Human beings are exhaustively
governed by physical laws so that no non-physical causes must be
invoked to explain their behavior, but since they are also subjects of
non-physical minds, these minds must be causally irrelevant. Whenever
our trust in the causal authority of the physical is overwhelmed by
our first-person experience of ourselves as creatures with an
essentially non-physical mind, epiphenomenalism is waiting in the
wings. This holds for Huxley's version of epiphenomenalism no less
than for modern property-epiphenomenalism–both are driven by the idea
that some of our mental life is distinct from that part of the
physical that is the ultimate and only authority with regard to
causation.
b. Arguments from the Debate about Mental Causation

Those who defend epiphenomenalism typically do so because they fail to
see how it could not be true. How could our mind make a causal
difference to our physical body? This is the so-called "problem of
mental causation." That there is mental causation is part and parcel
of our self-conception as freely deliberating agents that are the
causal origins of their actions and do what they do because they have
the beliefs and desires they have. Yet, the How of mental causation
constitutes a serious philosophical problem. Its solution requires an
account that shows exactly how the mental fits into the causal
structure of an otherwise physical world in such a way as to exert a
genuine causal influence, and any such account faces at least three
difficulties. First, causation seems to require laws, but there are
grounds for denying the existence of appropriate laws connecting the
mental and the physical (the "Argument from the Anomaly of the
Mental"). Second, causation is arguably a local or intrinsic affair,
while in the case of beliefs and desires, for instance, those aspects
constitutive of them insofar as they are mental are arguably
relational or extrinsic (the "Argument from Anti-Individualism").
Third, we do not understand how the mental can be causally efficacious
without coming into conflict with other parts of the causal structure
we know (or at least suspect) to play an indispensable causal role in
the production of physical effects (the "Argument from Causal
Exclusion").
i. The Argument from the Anomaly of the Mental

The Anomalous Monism of Donald Davidson was one of the earliest
versions of non-reductive physicalism (see Davidson 1970). Davidson
devised it to reconcile the idea that the mental is part of the
physical causal network with the idea that we are autonomous agents in
voluntary control of our actions. The problem is that the latter idea
requires, while the former explicitly denies, that "[m]ental events
such as perceivings, rememberings, decisions, and actions resist
capture in the nomological net of physical theory" (Davidson 1970,
207). On the one hand, since cause and effect must always fall under a
strict causal law, if the mental is to be causally efficacious, it
must be subject to strict laws. On the other hand, we can be
autonomous agents only if the mental is not part of the potentially
deterministic nomological network of physics; true autonomy requires
that there be no strict laws connecting mental events with other
mental events or with physical events and that the concepts necessary
to describe, explain and predict actions and to ascribe attitudes not
be reducible by definition or natural law to the concepts employed by
physical sciences (Davidson 1970, 212). The exact nature of Davidson's
argument for this "anomaly of the mental" is a matter of dispute, but
his idea seems to be that the existence of strict psychophysical or
psychological laws, together with the strict and potentially
deterministic physical laws, would be at odds with the essentially
holistic and rational nature of belief attributions (Davidson 1970,
219-221.) If causation requires causes and effects to fall under
strict laws, and if there are no strict laws concerning mental events,
mental causation seems to be impossible. This is the "Argument from
the Anomaly of the Mental." One response would be to abandon the
requirement that causes and effects must fall under strict laws.
Another response would be to retain the causal law requirement but to
deny that the mental is anomalous in the relevant sense. Davidson
himself did neither of these. His Anomalous Monism was designed to
show that mental causation is in fact compatible with the causal law
requirement and the absence of strict psychological and psychophysical
laws. Davidson derived Anomalous Monism from the following three
seemingly inconsistent premises: (1) Principle of Causal Interaction:
At least some mental events causally interact with physical events.
(2) Principle of the Nomological Character of Causality: Events
related as cause and effect fall under strict causal laws. (3)
Principle of the Anomalism of the Mental: There are no strict
psychological or psychophysical laws on the basis of which mental
events can be predicted and explained. (1) and (2) apparently imply
the falsity of (3): "it is natural to reason that the first two
principles [...] together imply that at least some mental events can
be predicted and explained on the basis of laws, while the principle
of the anomalism of the mental denies this" (Davidson 1970, 209).
Davidson's goal was to interpret (1), (2), and (3) in such a way that
they are not only consistent but jointly entail that particular mental
events which causally interact with other events are identical to
physical events. According to Davidson, (1) is an extensional claim
about a relation between particular events: although the assertion of
the causal relation between two events c and e requires describing
them, the causal relation itself holds "no matter how they are
described" (Davidson 1993, 6; 1970, 215). In contrast, (2) and (3)
concern laws. Since "laws are linguistic" (Davidson 1970, 215) and
thus an intensional affair, particular events fall under laws "only as
described." (2) says that whenever two events c and e are related as
cause and effect, there are descriptions "dc" and "de" of c and e,
respectively, under which c and e instantiate a causal law, although
there may be descriptions "d*c" and "d*e" under which they do not
instantiate a causal law (although "d*c caused d*e" is nevertheless a
true singular causal statement). Given this, it is easy to see why
Davidson thinks that (1), (2), and (3) entail that mental events which
causally interact with other events must be identical to physical
events. By (1), some mental event m causes or is caused by a physical
event p. By (2), m and p must therefore instantiate a strict causal
law. That is, there must be descriptions "dm" and "dp" of m and p,
respectively, such that "dm-events cause dp-events" (or "dp-events
cause dm-events") is a strict causal law. By (3), this can only be a
physical law. Hence, "dm" and "dp" must belong to the vocabulary of
physics. Since events are mental or physical "only as described" and
since m has with "dm" at least one physical description, m must thus
be a physical event (Davidson 1970, 224). However, while causation may
admittedly be an extensional relation between particular events, many
philosophers have argued that which causal relations an event enters
into is determined by which event-types it falls under. The singing's
being the singing of a high C, it seems, is causally relevant for its
causing the shattering, while its being the singing of the word
"freedom" is not. According to Anomalous Monism, Davidson's critics
claim, only the strict laws of physics can be causal laws, and hence
events seem to be causally related only in virtue of falling under
physical event-types, rendering mental event-types causally
irrelevant:

Davidson's argument for Anomalous Monism shows that any causal
relation involving a mental event and a physical event holds only
because a strict physical law subsumes the two events under physical
kinds or descriptions. The fact that the mental event is a mental
event, or that it is the kind of mental event that it is, appears to
be entirely immaterial to the causal relation. [...] Individual mental
events [...] do have causal efficacy, but only because they fall under
physical kinds, and the mental kinds that they are have [...] nothing
to say about what causal relations they enter into. The causal
structure of the world is wholly determined by the physical kinds and
properties instantiated by events of this world. (Kim 2003b, 126)

This is a prominent objection against Anomalous Monism (see, for
example, Honderich 1982; Kim 1989a, 1993a; Sosa 1993). Anomalous
Monism may avoid token- or event-physicalism, but it seems to succumb
to type- or property-epiphenomenalism: mental events, by being
identical to physical events, are causally efficacious, but that they
are the kind of mental event they are adds nothing to their causal
efficacy (for responses on behalf of Anomalous Monism see Campbell
1997, 1998; Davidson 1993; Lepore & Loewer 1987; McLaughlin 1989).
ii. The Argument from Anti-Individualism

Anti-individualism or externalism holds that the content of mental
states and the meaning of some natural language terms is a relational,
or extrinsic, rather than a local, or intrinsic, property (see Burge
1979; Putnam 1975). What are local or relational properties? Suppose
Sarah weighs 110 pounds, is four foot five, has blond hair and is
taller than Jack. The first three properties seem to be local in the
sense that they supervene upon Sarah's internal make-up and Sarah can
acquire or loose them only if she herself undergoes some change. The
fourth property, in contrast, seems to be relational in the sense that
Sarah has it only by courtesy of certain external facts, namely, only
if there is someone else, Jack, who is smaller than she is. If Jack
grows tall enough, Sarah loses the property of being taller than Jack,
although she herself does not undergo any change. According to Hilary
Putnam, meanings of natural kind terms are relational properties (see
Putnam 1975). What Sarah means by an utterance of, say, "water,"
"tiger," "elm," or "gold" is not determined solely by her internal
make-up, but also by her environment. Consequently, such terms can
mean different things in the mouth of molecularly identical twins that
are indistinguishable with regard to their local properties. Meanings
"just ain't in the head," as Putnam famously put it. Moreover, the
contents of the corresponding thoughts seem to be relational
properties, too: what Sarah believes when she has a belief she would
express as, say, "Water is wet" is determined by the way the world is
and not solely by how things are "inside" her. Tyler Burge went even
further and argued that natural kind terms are not the only terms
whose meaning is determined by external factors and that not only
differences in the physical environment can affect the meaning of a
term or the content of a belief, but also differences in a subject's
historical, linguistic, or social environment (see Burge 1979).
Externalism or anti-individualism makes mental causation problematic.
Causality seems to be an entirely local affair in the sense that a
system's behavior apparently supervenes upon its internal make-up.
Consequently, two systems exactly alike in all internal respects will
behave in exactly the same way, so that relational properties like
being a genuine dollar coin or being a photo of Sarah do not seem to
make a difference to the behavior of, say, a vending machine or a
scanner: as long as the piece of metal inserted into a vending machine
has a certain set of local properties, the vending machine will
exhibit a certain behavior, no matter whether the piece of mental
inserted is a genuine dollar coin or a counterfeit, and a scanner will
produce a certain distribution of pixels on the screen, no matter
whether the object scanned is a photo of Sarah or a piece of paper
locally indistinguishable from a photo of Sarah. The assumption that
causation is a local affair, when combined with externalism or
anti-individualism, leads to epiphenomenalism: the meaning or content
of a mental state, being a relational property, threatens to be as
irrelevant for our behavior as the property of being a genuine dollar
coin is for the behavior of a vending machine. In order to avoid
epiphenomenalism, we must either eschew anti-individualism or show how
relational mental properties can make a causal difference. Jerry Fodor
tried to explicate a notion of "narrow content" according to which the
mental states of intrinsically indistinguishable subjects must have
the same contents, although their relationally individuated "wide
contents" may differ (see Fodor 1987, ch. 1, 1991). Since narrow
contents supervene upon the intrinsic make-up of a subject, Fodor
held, the charge of epiphenomenalism can be avoided. However, he has
recently given up on this idea because it proved extremely difficult
say exactly what narrow contents are (see Fodor 1995). Frank Jackson
and Philip Pettit argue that relational properties can be causally
relevant in virtue of figuring in so called "program explanations,"
although strictly speaking the causal work is done solely by local
properties (see, e.g., Jackson & Pettit 1990). In a similar vein,
Lynne Rudder Baker and Tyler Burge claim that the charge of
epiphenomenalism "just melts away" (Baker 1993, 93) if we acknowledge
that our explanatory practice which undoubtedly treats explanations in
terms of relational properties as causal explanations trumps any
metaphysical armchair argument to the contrary (see Baker 1993, 1995;
Burge 1993). And Fred Dretske argues that while the triggering causes
of behavior are always local, relational mental properties can make a
causal difference in virtue of being structuring causes of behavior,
that is, in virtue of structuring a causal system in such a way that
the occurrence of a triggering neurophysiological cause causes a given
behavioral effect (see, for example, Dretske 1988).
iii. The Argument from Causal Exclusion

Most philosophers nowadays defend some version of non-reductive
physicalism. According to non-reductive physicalism, all
scientifically respectable entities are physical entities, where
entities which cannot be straightforwardly reduced to physical
entities—mental events or properties, for instance—are physical at
least in the broad sense that they supervene or depend upon physical
entities. Non-reductive physicalism is attractive because it promises
to respect the naturalistic attitude characteristic of our modern
scientific time while at the same time also preserving our
self-conception as autonomous agents. For decades, however, Jaegwon
Kim has argued that non-reductive physicalists unwittingly commit
themselves to epiphenomenalism. His master argument is the so-called
Causal Exclusion Argument, which he uses as a reductio ad absurdum of
non-reductive physicalism: if the mental were merely supervenient upon
but not reducible to the physical, as non-reductive physicalism holds,
it would be causally irrelevant (barring overdetermination).
Non-reductive physicalism is thus unable to steer a safe path between
the Scylla of reductionism on the one hand and the Charybdis of
epiphenomenalism on the other, so that those unwilling to embrace
outright reductionism are forced to accept epiphenomenalism. Kim's
most recent version of the Causal Exclusion Argument, the so-called
Supervenience Argument, has two stages. Stage one holds that mental
properties (or, rather, their instances–a qualification that will be
omitted from now on) can cause other mental properties only if they
can cause physical properties. Stage two then holds that mental
properties can cause physical properties only if they are reducible to
physical properties or genuinely overdetermining. Since
overdetermination can be ruled out, the only remaining alternatives
are "reduction or causal impotence" (Kim 2005, 54). Suppose a mental
property M causes a mental property M*. Since mind-body supervenience
"is a shared minimum commitment of all positions that are properly
called physicalist" (Kim 2005, 13), non-reductive physicalism must
posit a physical supervenience base P* of M* which is (non-causally)
sufficient for M*. What, then, is responsible for M*'s occurrence—M or
P*? There appears to be "a tension between vertical determination and
horizontal causation" (Kim 2003a, 153): "under the assumption of
mind-body supervenience, M* occurs because its supervenience base P*
occurs, and as long as P* occurs, M* must occur [...] regardless of
whether or not an instance of M preceded it. This puts the claim of M
to be a cause of M* in jeopardy: P* alone seems fully responsible for,
and capable of accounting for, the occurrence of M*" (Kim 1998, 42).
The upshot of this first stage of the argument is that the tension
between M and P* can be resolved only by accepting that "M caused M*
by causing its supervenience base P*" (Kim 2005, 40). Stage two then
goes on to argue that mental-to-physical causation is impossible.
Given the so-called causal closure of the physical, P* must have a
sufficient and completely physical cause P, leading to a competition
between M and P for the role of P*'s cause. Barring overdetermination,
M seems bound to loose this competition: if P is a sufficient cause of
P*, then once P is instantiated all that is required for P* to occur
is done and there is nothing left for M to contribute, causally
speaking. This completes stage two of the Causal Exclusion Argument.
Both steps together seem to lead to epiphenomenalism–unless mental
properties are reducible or genuinely overdetermining, they must be
causally inert, so that with the overdetermination option and the
reduction option ruled out, epiphenomenalism is the inevitable
consequence. In response, non-reductive physicalists have offered
compatibilist accounts of mental causation designed to explain how
irreducible mental properties can play a substantial causal role in
the production of physical effects, given that the causal work is done
solely by physical properties. The common core of these attempts is
the idea that there is some compatibilist condition C such that (1.)
fulfilling C is sufficient for being causally relevant; (2.)
properties which do not do any real causal work can fulfill C; (3.) C
can be fulfilled by two or more properties without leading to any kind
of "causal competition;" and (4.) mental properties can fulfill C.
Prominent compatibilist candidates for C include figuring in
counterfactual dependencies (see LePore & Loewer 1987) or program
explanations (see Jackson & Pettit 1990), being a determinable of the
physical properties which do the causal work (see Yablo 1992), or
falling under non-strict causal laws (see Fodor 1989; McLaughlin
1989).
c. Libet's Experiments

Intuition tells us that we, as conscious selves, are in charge of our
actions, and the man in the street finds the idea that consciousness
is a causally irrelevant by-product of brain processes preposterous.
Empirical scientists, however, have long questioned these assumptions.
Many of them think that the brain causes our actions and then makes us
think that it was us who did it: "The unique human convenience of
conscious thoughts that preview our actions gives us the privilege of
feeling we willfully cause what we do. In fact, unconscious and
inscrutable mechanisms create both conscious thought about action and
the action, and also produce the sense of will we experience by
perceiving the thought as cause of the action" (Wegner 2002, 98). No
empirical research has provoked more philosophical discussion than
Benjamin Libet's experiments concerning the relationship between
unconscious brain activity and the subjective feeling of volition
during the initiation of simple motor actions (see Libet et al. 1983;
Libet 1985). Previous research had shown that actions that are
perceived to be the result of a conscious feeling of volition are also
preceded by a pattern of brain activity known as the "readiness
potential." The question Libet and his colleagues wanted to answer
was: What comes first—the feeling of volition or the readiness
potential? They instructed subjects to perform a simple motor
activity, like pressing a button, within a certain time frame at an
arbitrary moment decided by them ("Let the urge to act appear on its
own any time without any preplanning or concentration on when to act";
Libet et al. 1983, 625). The subjects were asked to remember exactly
when they made the decision, when they were first aware of the "urge
to act," by noticing the position of a dot circling a clock face (the
"clock" being a cathode ray oscilloscope modified so as to be able to
measure time intervals of roughly fifty milliseconds). The time when
the action was carried out, when the subjects actually pressed the
button, was measured by electronically recording the position of the
dot. On average, it took about 200 milliseconds from the first
conscious feeling of voliton to the actual pressing of the button. But
Libet and his collaborators also recorded the subjects' brain activity
by means of an EEG. They found that an increased electrical activity,
the so-called "readiness potential," was built up (primarily in the
secondary motor cortex) on average approximately 500 milliseconds
before the button was pushed, and that means approximately 300
milliseconds before the subjects felt the conscious "urge to act"
(Libet's experiments have been repeated and improved several times;
see, e.g. Keller & Heckhausen 1990; Haggard & Eimer 1999; Miller &
Trevena 2002; Trevena & Miller 2002). It is tempting to interpret this
result as showing that the allegedly free decision of the subject was
in fact determined by unconscious brain processes and that, at least
insofar as decisions to act are concerned, our mind is a mere
epiphenomenon, but it remains a controversial issue exactly what
philosophical consequences we ought to draw from Libet's experiments
(see Pockett et al. 2006).
5. Arguments against Epiphenomenalism

Epiphenomenalism has had few friends. It has been deemed "thoughtless
and incoherent" (Taylor 1927, 198), "unintelligible" (Benecke 1901,
26), "quite impossible to believe" (Taylor 1963, 28) and "truly
incredible" (McLaughlin 1994, 284). The resistance stems from the fact
that many think that if epiphenomenalism were correct, we could not be
the kind of being we are and we could not occupy the place in the
world we occupy. We would instead be at the mercy of our brains and we
would have to say that our actions are all our brains' actions and
that ultimately "we" have nothing to do with them.

If the eyebrows are raised they are not raised by us. What is done
is not done by us. [...] We go piggy-back, and we cannot get off.
Where it goes, we go. What's "it"? The body/brain is "it." "It" is not
us, is the point. Epiphenomenalism would be the ruin of the self and
that self's life. […] Our supposed self is illusory, and we are
deluded. [...] We lose ourselves when consciousness ceases to be
effective in what we chose. (Hyslop 1998, 68)

In his book The Fundamental Questions of Philosophy, Alfred Cyril
Ewing introduced epiphenomenalism as a theory that can be disposed of
in a "conclusive fashion" (Ewing 1953, 127): "That epiphenomenalism is
false is assumed in all practical life [...] and it is silly to adopt
a philosophy the denial of which is implied by us every time we do
anything" (Ewing 1953, 128). But what exactly is it that renders
epiphenomenalism so evidently absurd?
a. The Argument from Counterintuitiveness

Epiphenomenalism is counterintuitive. There's no doubt about that.
Yet, philosophy, like all science, is not concerned with intuitiveness
but with truth, and that a theory is counterintuitive does not show
that it is not true. In fact, a host of widely accepted and feted
theories are counterintuitive at first and some remain so forever: the
Copernican system, the Freudian theory of the unconscious, Einstein's
theories of special and general relativity or quantum mechanics.
Einstein's theory of relativity, for instance, is much less intuitive
than Newtonian physics, but ultimately the fate of a theory depends on
whether there are good arguments in favor of it, not on whether it is
intuitive. If there are reasons for taking epiphenomenalism seriously,
then we should do that, just as we do it in the case of the theory of
relativity: "Epiphenomenalism may be counterintuitive, but it is not
obviously false, so if a sound argument forces it on us, we should
accept it" (Chalmers 1996, 159).
b. The Argument from Introspection

It might seem as if we can be introspectively aware of chains of
mental occurrences, one of which is causing the other, for instance
when we reason through an argument, write a piece of prose, or acquire
a new belief by inferring it from previously held beliefs. We just
know, it seems, that in these cases there is mental causation. The
same may be said to be true of various chains of occurrences both
inside and outside of our mind, for instance when volitions give rise
to appropriate behavior, when a pain results in a wincing, or when
fear makes our heart beat faster–one might say that in these cases,
too, we have some immediate cognitive access to the causal efficacy of
the mental. If we could indeed be in some sense "directly acquainted"
with the fact that such sequences are the result of genuinely causal
processes, epiphenomenalism would not be an option. Yet, our awareness
of regular successions does not and cannot reveal their causal nature.
The awareness of the psychological or psychophysical sequences that
make up our everyday life is no more awareness of causal processes
than awareness of the sequence of shadows a moving car casts (Lachs
1963, 189). Whatever those who hold that epiphenomenalism is
"incompetent to take account of the obvious facts of mental life"
(Taylor 1927, 198) mean, they cannot mean that it is contradicted by
our immediate cognitive access to our mind's causal effectiveness,
because there is no phenomenological difference between a situation in
which epiphenomenalism is false and a situation in which
epiphenomenalism is true.
c. The Argument from Evolution

One of the earliest objections to epiphenomenalism starts with the
observation that we have the properties we have because they
contributed positively to our ancestors' differential fitness and that
a property which endows an organism with an evolutionary advantage
must make a causal difference to its survival. Since we have mental
properties, while our ancient ancestors did not, the argument
continues, these properties must have evolved over time and therefore
must be capable of making a causal difference (this argument is
frequently attributed to Popper & Eccles 1977, but it was endorsed
already by James 1879). Epiphenomenalists respond that mental
properties may have evolved as nomologically necessary by-products of
adaptive traits. A polar bear's having a heavy coat decreases its
fitness (by slowing it down), but is nevertheless an evolved trait
because it was an inevitable by-product of a highly adaptive trait,
namely, having a warm coat: "Having a heavy coat is an unavoidable
concomitant of having a warm coat [...], and the advantages for
survival of having a warm coat outweighed the disadvantages of having
a heavy one" (Jackson 1982, 134). Likewise, it could be that we enjoy
our mental life because its neurophysiological causes contributed
positively to our ancestors' differential fitness by making them
"fitter" compared to those who lacked such neurophysiological
equipment. Maybe we have a mind because it was evolutionary adaptive
to have a big brain and it is nomologically impossible to have a big
brain without having a mind. The problem with this response is that
while we understand perfectly well why polar bears can have warm coats
only in virtue of having heavy coats, we have little or no idea why it
should be necessary to have a mind in order to have a big brain. Why
should of all neurophysiological structures only those with a causally
irrelevant mind as by-product be able to do what was required for our
ancestors' survival? If a company claims that religion is not an
employment criterion, but it turns out that all its employees are of
the same religion, that cries out for an explanation, and the same
holds if the epiphenomenalist claims that although our mind is totally
ineffective, during the course of evolution only brain structures have
evolved that are accompanied by a mind as a by-product.
d. The Argument from the Impossibility of Knowledge of Other Minds

Another problem is that epiphenomenalism seems to render our standard
response to the other minds problem impossible. According to that
response, our belief that our fellow human beings have a mental life
similar to ours is justified by an argument from analogy, stated in
its classic form by John Stuart Mill and Bertrand Russell (Mill 1865,
190-191; Russell 1948, 208-209 & 501-504). Since our own body and
outward behavior are observably similar to the body and the behavior
of our fellow human beings, we are justified by analogy in believing
that they enjoy a mental life similar to ours. The idea is to infer
like mental causes from like behavioral effects and this does not work
for the epiphenomenalist who denies that there are any mental causes.
(This is an objection to epiphenomenalism only if the argument from
analogy does indeed provide a good solution to the other minds
problem, and that is far from obvious–notoriously, inductions based on
a single positive instance are problematic and in the case of other
minds there is no independent way of verifying the conclusion.) The
epiphenomenalist can employ the same strategy as in the case of the
argument from evolution and insist that our inference to the mental
life of others need not advert to causality all the way up. If the
similar behavior and the similar body of others provide evidence for
anything, they provide evidence for the assumption that they are in
physical states relevantly similar to those which, in us, are causally
responsible for our mental life. This inference is not one from
outward behavior to inward mental causes, but from outward behavior to
inward neurophysiological causes and from there on further to inward
mental effects, but it seems that it is no less reliable (see Benecke
1901; Jackson 1982).
e. The Argument from Davidson's Reasons for / Reasons for which Distinction

Davidson famously pointed out that I may have a reason for performing
an action, perform that action, and yet not perform it for that reason
(Davidson 1963, 9). Suppose, for instance, I want to meet my mistress
and I believe that I can attain this goal by giving her a call;
suppose I also have a second-order desire to get rid off my
first-order desire and I believe that I can attain this goal by
calling my psychiatrist. When I finally walk to the phone, it seems, I
have a reason for doing so (my first-order desire plus my
corresponding belief) which is not the reason for which I walk to
phone (Wilson 1997, 72). According to Davidson, the reasons for an
action and the reasons for which the action is performed can be easily
distinguished: the reasons for which an action is performed are those
which cause the action. This explanation is not available to the
epiphenomenalist who holds that no reason ever causes an action.
(Again, this is an objection against epiphenomenalism only if
Davidson's distinction makes sense; see Latham 2003 for the view that
it doesn't.) In response, however, the epiphenomenalist can hold that
the reasons for which an action is performed are those that are caused
by the neurophysiological cause of the action.
f. Other Arguments

Knowledge, memory, justification, meaning and reference all seem to
require the causal efficacy of what is known, remembered, believed,
meant or picked out. How, for instance, could we say that Sarah knows
that there is orange juice in the fridge or that her belief that there
is orange juice in the fridge is justified, if her belief were in no
way causally connected to the fridge or the orange juice? The causal
relation does not have to be direct–it may be that Sarah's mother saw
the orange juice in the fridge, told it to Sarah's sister who in turn
told it to Sarah, causing her thereby to believe that there is orange
juice in the fridge. Most of our knowledge depends upon such indirect
causal chains. We are not in direct causal contact with Plato, the
cholera, Caesar's crossing of the Rubicon or the outbreak of World War
I, but we can have knowledge about these things because we are linked
to them by long causal chains starting with someone who was in direct
causal contact with them. According to a causal theory of knowledge,
knowledge is impossible without such a causal chain, and something
similar holds for justification, memory, meaning, and reference. If
Sarah believes that it rained on February 1, 1953 in Amsterdam, but
the rain on February 1, 1953 in Amsterdam is not causally related in
any way to Sarah's belief, then it seems that her belief cannot be
justified; if the rain on that day is not causally related to Sarah's
current mental states in any way, then it seems that she cannot
remember the rain on February 1, 1953 in Amsterdam; and one reason why
Sarah's twin on Putnam's famous Twin Earth (see Putnam 1975) cannot
refer to water and why by using the word "water" she cannot mean water
is that she never did causally interact with water. If knowledge,
justification, memory, meaning and reference require a causal contact
with what is known, believed, remembered, meant and picked out,
epiphenomenalism implies that we cannot have knowledge of or justified
beliefs about mental states (our own or those of others), that we
cannot remember past mental states, cannot refer to mental states and
cannot make meaningful statements about them. However, it is absurd to
hold that Sarah cannot know that she is having a toothache, that she
cannot remember the feeling she had when she fell in love for the
first time etc. Moreover, if a causal theory of meaning or reference
is correct, then the very statements the epiphenomenalist uses to
formulate her position are meaningless: "if the mental contributes
nothing to the way in which the linguistic practices involving
'[psychological' terms are developed and sustained in the
speech-community [...] then [this] would deprive the epiphenomenalist
of the linguistic resources to enunciate his thesis" (Foster 1996,
191). To the extent that epiphenomenalism aspires to make a meaningful
statement about the nature of our mental life, it would thus be
self-refuting since that is impossible if it is true (see Robinson
2006 for a discussion of this problem and for a reply on behalf of
epiphenomenalism). Even if the epiphenomenalist could somehow
formulate her position, it would be a pointless exercise from her
point of view to try to convince us of its truth, because if she is
right, rational considerations can have no causal influence upon our
beliefs and actions. In response, the epiphenomenalist could argue
that a causal chain cannot always be required because Sarah can know,
justifiably believe or remember that bachelors are unmarried and that
two plus two equals four, or use the term "the biggest star in the
universe" to refer to an object even if she never causally interacted
with bachelors, the number two or the biggest star in the universe.
The problem, however, is that our knowledge and our memories of and
our talk about our mental states seem to be fundamentally different
from the typical examples of knowledge, memory, or reference that are
possible without a causal contact. As Dieter Birnbacher points out
(before he goes on the defend epiphenomenalism against this charge):
"[such] examples show that a causal theory of knowledge cannot claim
to cover all and every kind of knowledge. But this doesn't mean that a
causal theory of knowledge is implausible for other, and admittedly
central, kinds of knowledge such as knowledge by perception and
introspection" (Birnbacher 2006, 123-124). The epiphenomenalist has to
offer a constructive account of what, if not a causal relation,
grounds knowledge, justification, memory, meaning, and reference in
the case of mental states. According to David Chalmers, for instance,
in the case of phenomenal mental states, knowledge and justification
are an immediate consequence of the fact that we have these
experiences: "it is having the experiences that justifies the beliefs
[about our experiences]" (Chalmers 1996, 196), because "[t]o have an
experience is automatically to stand in some sort of intimate
epistemic relation to the experience" (Chalmers 1996, 196-197). Since
the epiphenomenalist admits that we have experiences and since we
cannot have experiences without knowing that we have them, the
epiphenomenalist can admit that we can have knowledge of our
experiences. Chalmers also develops a non-causal account of memory and
reference (Chalmers 1996, 192-203; see Robinson 1982, 2006 for
competing but related proposals). Although there may be problems with
such accounts, it certainly seems plausible to ask why the opponents
of epiphenomenalism insist that the relation that grounds knowledge,
justification, memory, reference and meaning must be causal through
and through. According to the epiphenomenalist, when Sarah knows that
she has a toothache or remembers the feeling she had when she first
fell in love, there is a causal chain which leads from the
neurophysiological cause of her toothache or her feeling to her
current state of knowledge or memory. Why should such a chain be less
capable of grounding knowledge or memory than a causal chain which
starts with the toothache or the feeling itself? To insist without
further explanation that the link has to be causal through and through
does not tell us what the apparently indispensable je-ne-sais-quois
about such a causal link is, without which knowledge, memory etc. are
supposed to be impossible (see Pauen 2006 and Staudacher 2006 for
further discussion). There are various objections against
epiphenomenalism, nearly all of which are based upon the claim that
this or that undeniable fact would be impossible if epiphenomenalism
were true. In response, the epiphenomenalist typically points out that
the causal relation she says holds between mental states and their
neurophysiological correlates ensures that whenever her opponents
appeal to a mental cause to account for some apparently undeniable
fact, she can appeal to a physical cause which is correlated with the
alleged mental cause with nomological necessity and does exactly the
same causal job.
6. References and Further Reading

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* Baker, L. (1995). Explaining Attitudes. Cambridge: Cambridge
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* Benecke, E. (1901). On the aspect theory of the relation of mind
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* Birnbacher, D. (2006). Causal interpretations of correlations
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* Bonnet, C. (1755). Essai de Psychologie. Ou Considerations de
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* Burge, T. (1979). Individualism and the mental. Midwest Studies
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* Burge, T. (1993). Mind-body causation and explanatory practice,
Mental Causation, hrsg. v. J. Heil & A. Mele, 97-120. Oxford:
Clarendon Press.
* Campbell, N. (1997). Anomalous monism and the charge of
epiphenomenalism. Dialectica, 52, 23-39.
* Campbell, N. (1998). The standard objection to anomalous monism.
Australasian Journal of Philosophy, 75, 373-382.
* Chalmers, D. (1996). The Conscious Mind: In Search of a
Fundamental Theory. Oxford: Oxford University Press.
* Davidson, D. (1963). Actions, reasons, and causes. Journal of
Philosophy, 60, 685-700. Reprinted in Essays on Actions and Events,
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* Davidson, D. (1970). Mental events, Experience and Theory, ed.
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Massachusetts Press and Duckworth. Reprinted in Essays on Actions and
Events, 207-225. Oxford: Clarendon Press 1980.
* Davidson, D. (1993). Thinking causes, Mental Causation, ed. J.
Heil A. Mele, 3-17. Oxford: Clarendon Press.
* Dretske, F. (1988). Explaining Behavior: Reasons in a World of
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* Dretske, F. (1989). Reasons and causes. Philosophical
Perspectives, 3, 1-15.
* Ewing, A. (1953). The Fundamental Problems of Philosophy. New
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* Fodor, J. (1987). Psychosemantics. Cambridge, MA: MIT Press.
* Fodor, J. (1989). Making mind matter more. Philosophical Topics,
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* Fodor, J. (1991). A modal argument for narrow content. Journal
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* Fodor, J. (1995). The Elm and the Expert: Mentalese and its
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* Foster, J. (1996). The Immaterial Self. London: Routledge.
* Haggard, P. & Eimer, M. (1999). On the relation between brain
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* Huxley, T.H. (1898). Hume with Helps to the Study of Berkeley.
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* Hyslop, A. (1998). Methodological epiphenomenalism. Australasian
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* Jackson, F. (1982). Epiphenomenal qualia. Philosophical
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* James, W. (1879). Are we automata? Mind, 4, 1-22.
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* Kim, J. (1989a). The myth of nonreductive materialism.
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* Kim, J. (1998). Mind in a Physical World: An Essay on the
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* Kim, J. (2003a). Blocking causal drainage and other maintenance
chores with mental causation. Philosophy and Phenomenological
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* Kim, J. (2003b). Philosophy of psychology, Donald Davidson, ed.
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* McLaughlin, B. (1989). Type epiphenomenalism, type dualism, and
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* Yablo, S. (1992). Mental causation. Philosophical Review, 101, 245-280.