## 1. Traditional Arguments (A) Pro



Many philosophers recognize a distinction between two kinds of mental
events. (A) The first goes by many names, e.g., phenomenal
experiences, occurrences of qualitative consciousness, the
what-it-is-like of experience, qualia.
Pains, afterimages, and tastes can serve as examples. (B) Mental
events of the second kind are occurrent propositional attitudes, e.g.,
(occurrent) beliefs and desires. Arguments about epiphenomenalism may
concern either type of mental event, and (as made clear in Campbell
1970) it should not be assumed that an argument given for one type can
be rephrased without loss for the other. The two types can often be
connected, however, through beliefs that one has one's
experiences. Thus, if it is held that pains have no physical effects,
then one must say either (i) pains do not cause beliefs that one is in
pain, or (ii) beliefs that one is in pain are epiphenomenal. For, if
pains caused beliefs that one is in pain, and the latter had physical
effects, then pains would, after all, have effects in the physical
world (albeit indirectly). But epiphenomenalism says mental events
have *no* effects in the physical world.[1]



The central motivation for epiphenomenalism lies in the premise that
whenever there is a sufficient cause of a physical event, there is a
sufficient *physical* cause of that event. If a mental event is
something other than a physical event, then for it to make any causal
contribution of its own in the physical world would require a
violation of physical law. Descartes' (1649) interactionist
model proposed that nonphysical events could cause small changes in
the shape of the pineal gland. But such nonphysical effects, however
slight, would mean that the physical account of motion is
*false* -- for that account says that there will be no
such change of shape unless there is a physical force that causes
it.



One may try to rescue mental efficacy by supposing that whenever there
is a mental effect in the physical world there is *also* a
physical force that is a sufficient cause of the effect. This view,
however, both offends Occamist principles and fails to satisfy the
leading anti-epiphenomenalist intuition, namely, that the mental
*makes a difference* to the physical, i.e., that it leads to
behavior that would not have happened in absence of the mental. The
view also leads to an epistemological problem: If there is always a
sufficient physical cause for whatever a mental event is supposed to
produce, then one could never be in a position where one
*needs* to suppose there is anything non-physical at work, and
thus there could never be any reason to introduce mental causes into
one's account of neural events or behavior.



Many contemporary thinkers would respond to the central motivation for
epiphenomenalism by denying its dualistic presupposition, i.e., by
holding that mental events are identical with physical events, and may
therefore have physical effects. Questions that remain for such
physicalistic views will be explained in section 3. For now, it should
be noted that the argument stated in the previous two paragraphs is
not supposed to be an argument for dualism, but only for adopting
epiphenomenalism, once dualism is accepted.



Further support for epiphenomenalism can be derived from the fact,
noted by Wilhelm Wundt (1912), that "each simple sensation is
joined to a very complicated combination of peripheral and central
nerve processes", together with the fact that the causes of
behavior are likewise complex neural events. This latter fact makes it
natural to look for complex events throughout the causal chain leading
to behavior; and these can be found in the neural events that are
required for the occurrence of simple sensations. The sensations
themselves could not contribute to behavior without first having
neural effects that are more complex than themselves. Thus an
anti-epiphenomenalist stance would require us to prefer the hypothesis
that simple sensations cause (relatively) complex neural events over
the hypothesis that complex neural events (that are required in any
case for the causation of sensations) are adequate to cause the neural
events required for the causation of behavior.


## 2. Traditional Arguments (B) Con (with Epiphenomenalists' Responses)


### 2.1 Obvious Absurdity



Epiphenomenalism is absurd; it is just plain obvious that our pains,
our thoughts, and our feelings make a difference to our (evidently
physical) behavior; it is impossible to believe that all our behavior
could be just as it is even if there were no pains, thoughts, or
feelings. (Taylor, 1963 and subsequent editions, offers a
representative statement.)



This argument is surely the briefest of those against
epiphenomenalism, but it may have been more persuasive than any other.
Epiphenomenalists, however, can make the following reply. First, it
can never be obvious what causes what. Animated cartoons are full of
causal illusions. Falling barometers are regularly followed by storms,
but do not cause them. More generally, a regularity is causal only if
it is not explained as a consequence of underlying regularities. It is
part of epiphenomenalist theory, however, that the regularities that
we observe to hold between mental events and actions can be explained
by underlying regularities. Schematically, suppose physical event
\(P\_1\) causes both mental event \(M\) and physical successor \(P\_2\),
as in Figure 1.




\[\begin{array}{ccccccc}
M & & & & & & \\
 \uparrow & & & & & & \\
 P\_1 & \rightarrow & P\_2 & \rightarrow & P\_3 & \rightarrow & \cdots 
\end{array}\]


Figure 1.




Suppose there is no other cause of \(M\), and no other cause of
\(P\_2\). Then every \(M\) will be followed by \(P\_2\), yet the cause
of \(P\_2\) will be adequately found in \(P\_1\). It is true that, under
the assumptions stated, the counterfactual, "If \(M\) had not
occurred, then \(P\_2\) would not have occurred" holds; but then,
so may "if the barometer had not fallen, the storm would not
have occurred." The moral to be drawn is that causation may
imply that certain counterfactuals hold, but the holding of
counterfactuals is not enough to show causation. Thus, it is true that
some of our actions would not have occurred, under normal conditions,
unless we had had certain mental events. But this fact cannot show
that those actions are caused by our mental events (rather than being
caused by the physical causes of those mental events).



It is often said that pains cause withdrawals of affected parts of the
body. In extreme cases, however -- for example in a case of
touching a hot stove -- it can be observed that the affected part
is withdrawn *before* the pain is felt. These cases cannot show
that pain never causes withdrawals, but they do show that pain is not
necessary as a cause of withdrawals. In less extreme cases, it is open
to the epiphenomenalist to hold that the causal order is the same as
in the extreme cases (i.e., some physical event, \(P\_1\), causes both
withdrawal and pain) but is not ordinarily recognized to be so.



A variant of the obvious absurdity objection is that epiphenomenalism
leads to a feeling of loss of self, or a sense that we can no longer
regard our actions as *ours*. (See Hyslop 1998. Baysan [2021]
argues to the contrary that epiphenomenalism is compatible with
agency.) Epiphenomenalists may, however, reply that there would be
different brain states corresponding to the difference between cases
of moving our bodies and cases of having our body parts moved by
something else, and their view allows different brain states to have
different phenomenological effects. Epiphenomenalism is also
compatible with there being a distinction between actions that proceed
from normal brain processes in normal conditions, and actions that
proceed from manipulation by others, disease, or situations that
overwhelm normal reasoning abilities.


### 2.2 Natural Selection



The development of consciousness must be explainable through natural
selection. But a property can be selected for only if it has an effect
upon organisms' behavior. Therefore, consciousness (both qualia
and intentional states) must have effects in behavior, i.e.,
epiphenomenalism is false. (See Popper and Eccles 1977; James 1879;
Romanes 1896; Klein 2019.)



According to the same biology that embraces natural selection,
however, behavior has muscular causes, which in turn have neural
causes. Barring neural events that are inexplicably in violation of
biological constraints on their conditions of activation, there must
be an adequate physical cause of every link in the causal chain
leading to behavior. Thus, it is easily understood how certain kinds
of neural events can be selected for. Epiphenomenalists hold that
conscious events are effects of (certain) neural events. Thus, it fits
well in their view that we have the conscious events we do because the
neural causes of these events have been selected for. Indeed, if
neural causes of behavior are selected for, and are sufficient causes,
there *cannot* be any *further* effect attributed to
natural selection.



William James (1879; 1890; see also Bradley, 2011) offered an
intriguing variant of the argument from natural selection. If pleasure
and displeasure have no effects, there would seem to be no reason why
we might not abhor the feelings that are caused by activities
essential to life, or enjoy the feelings produced by what is
detrimental. Thus, if epiphenomenalism (or, in James's own
language, automaton-theory) were true, the felicitous alignment that
generally holds between affective valuation of our feelings and the
utility of the activities that generally produce them would require a
special explanation. Yet on epiphenomenalist assumptions, this
alignment could not receive a genuine explanation. The felicitous
alignment could not be selected for, because if affective valuation
had no behavioral effects, misalignment of affective valuation with
utility of the causes of the evaluated feelings could not have any
behavioral effects either. Epiphenomenalists would simply have to
accept a brute and unscientific view of pre-established harmony of
affective valuation of feelings and the utility of their causes.



Epiphenomenalists can respond to James's argument by offering
support for the following two views. (I) There is a distinction
between (a) neural events in sensory systems, which cause feelings,
and (b) neural events in a reward system (where an event is a member
of a reward system if and only if it contributes to continuance (or,
discontinuance) or repetition (or avoidance) in similar circumstances,
of any behavior that leads to that event). (II) What
"pleasure" refers to in any possible world is the effect
in consciousness of the events in (b) that contribute to continuance
or repetition. Since both (a) events and (b) events have neural and,
ultimately, behavioral effects, they can be selected for, and so can
their combination. The alignment of feelings caused by useful stimuli
and pleasure (and, by parallel reasoning, alignment of feelings caused
by harmful stimuli and displeasure) would then follow from alignment
of neural events of the kinds described in (a) and (b). This latter
alignment is independently plausible. A reward system that can lead to
quick decisions and a sensory system that provides discriminations for
use in longer term planning would both confer advantages; and these
systems would, in general, have to work together in a successful
organism. (For fuller discussion of James's argument see
Robinson 2007, 2019; and for the structure of pleasure, see Robinson
2006b, 2019.)


### 2.3 Knowledge of Other Minds



Our reason for believing in other minds is inference from behavioral
effects to mental event causes. But epiphenomenalism denies such a
causal connection. Therefore, epiphenomenalism implies the
(exceedingly implausible) conclusion that we do not know that others
have mental events. (Jackson [1982] replies to this and several other
arguments against epiphenomenalism. The argument is stated, and
accepted, in Benecke 1901.)



The first premise of this argument is a widely held dogma, but it can
be denied without absurdity (see Robinson 1997). It is perfectly
obvious to everyone that the bodies of human beings are very much
alike in their construction, and it requires no sophisticated
reasoning to infer that if others are made like me, they probably hurt
when affected like me, e.g., when their bodies are stuck with pins,
beaten, cut and so on. There is no principle that makes an inference
from similar effects to similar causes more secure than an inference
from similar causes to similar effects; on the contrary, the latter
inference is more secure, because there can sometimes be quite
different causes of extremely similar effects. Thus, an inference to
other minds that is allowed by epiphenomenalism must be at least as
strong as the inferential route to other minds with which it is
incompatible.


### 2.4 Self-stultification



The most powerful reason for rejecting epiphenomenalism is the view
that it is incompatible with knowledge of our own minds -- and
thus, incompatible with knowing that epiphenomenalism is true. (A
variant has it that we cannot even succeed in referring to our own
minds, if epiphenomenalism is true. See Bailey 2006 for this
objection and Robinson 2012 for discussion.) If these destructive
claims can be substantiated, then epiphenomenalists are, at the very
least, caught in a practical contradiction, in which they must claim
to know, or at least believe, a view which implies that they can have
no reason to believe it. Moreover, unless epiphenomenalists can
consistently claim to know their own minds, they cannot offer the
response to the other minds objection given in 2.3 above. (See Walton,
1989.) (Many authors give some version of this objection. For a full
statement of this argument, and several others concerning
epiphenomenalism, see Chalmers 1996. For strong recent versions, see
DeBrigard 2014; Moore 2012 (responded to by Robinson 2013); and
Moore 2014. For recent discussion see Baysan 2021.)



The argument that is given to support the destructive claims is that
(i) knowledge of one's mental events requires that these events
cause one's knowledge, but (ii) epiphenomenalism denies physical
effects of mental events. So, either we cannot know our own mental
events, or our knowledge of them cannot be what is causing the plainly
physical event of our saying something about our mental events. Thus,
suppose \(S\) is an epiphenomenalist, and that \(S\) utters "I
am in terrible pain." \(S\) is committed to the view that the
pain does not cause the utterance. But then, it seems, \(S\) would be
making the same utterance whether or not a pain were occurring. If
this is so, then \(S\)'s testimonies about \(S\)'s own
pains are worthless -- both to us and to \(S\). They cannot be
taken to represent any knowledge about pains on \(S\)'s part (if
\(S\)'s epiphenomenalist view is true). In fact, on an
epiphenomenalist view, all the arguments for epiphenomenalism and
rebuttals to counterarguments we have reviewed might be given even if
we were all zombies -- i.e., even if we were all possessed of
physical causes of our utterances and completely devoid of any mental
life whatsoever.



The argument that epiphenomenalism is self-stultifying in the way just
described rests on the premise that knowledge of a mental event
requires causation by that mental event. But epiphenomenalists may
reject that premise without absurdity. One way of seeing how to do
this involves considering the interactionist diagram in Figure 2,
which shows \(P\_1\) as directly causing \(M\) but not \(P\_2\), and
\(M\) directly causing \(P\_2\). (Directly causing is an intransitive
relation. Causation (when used without modifier) is transitive: events
are causally related if there is a chain of direct causes, however
long, that connects them.)




\[\begin{array}{ccccccc}
M & & & & & & \\
 \uparrow & \searrow & & & & & \\
 P\_1 & & P\_2 & \rightarrow & P\_3 & \rightarrow & \cdots 
\end{array}\]


Figure 2.




Now consider \(P\_3\), which is directly caused by \(P\_2\) and which we
will assume to cause (directly or indirectly) further behavior such as
\(S\)'s utterance of "I am in terrible pain".
\(P\_3\) is not directly caused by \(M\). Does it convey knowledge of
\(M\)? If we answer negatively, on the ground that \(P\_3\) is not
directly caused by \(M\), we will be rejecting interactionism for
virtually the same reason that epiphenomenalism is thought to be
unacceptable. Since this is an extremely implausible stance, let us
take it that \(P\_3\) does convey knowledge of \(M\). But what property
does \(P\_3\) actually have that makes it a case of conveying knowledge
of \(M\)? Epiphenomenalists will wish to point out that \(P\_3\) does
not have any property that contains information as to how it was
caused. Looking backward from \(P\_3\), so to speak, one cannot tell
whether it was indirectly caused by \(M\) (as in the interactionistic
Figure 2) or indirectly caused by \(M\)'s cause (as in the
epiphenomenalistic Figure 1). There is, however, a property that
\(P\_3\) does have that is intuitively strongly connected to its
conveying knowledge of \(M\) -- namely, that it would not be
occurring unless \(M\) had recently occurred. But \(P\_3\) has this
property on epiphenomenalist and interactionist views alike. Thus, if
not occurring unless \(M\) has recently occurred is the property that
is responsible for \(P\_3\)'s conveying knowledge of \(M\),
epiphenomenalists have as much right as anyone to claim that \(P\_3\)
conveys knowledge of \(M\), and they are not debarred from knowing
what they claim to know.



Critics of epiphenomenalism can of course point out that there is a
property that interactionism, but not epiphenomenalism, assigns to
\(P\_3\) -- namely, the property of being indirectly caused by
\(M\). Epiphenomenalists, however, are likely to think that the
intuitive connection between this property and knowledge is much
weaker than that between knowledge of \(M\) and the fact that \(P\_3\)
would not be occurring unless \(M\) had recently occurred. In fact,
they may hold that the relevance of indirect causation is exhausted by
its ensuring that \(P\_3\) would not occur unless \(M\) had recently
occurred. They can then reiterate that there is another way of
ensuring that this condition holds, namely, the set of relations,
diagrammed in Fig. 1, that is affirmed by epiphenomenalism.



The foregoing way of responding to the self-stultification argument is
further explained and defended in Robinson (1982b, 2013; see also
2006a). An alternative response can be found in Chalmers 1996 (see
also Nagasawa 2010). Chalmers's property-dualistic view holds
that there is more to a person than just a brain and a body. It allows
for persons to be directly acquainted with experiences, and it is this
direct acquaintance, rather than any causal relation, that justifies
our beliefs about experiences. On this view, experiences are partially
constitutive of beliefs about experiences, and "the
justification of my belief [about experiences] accrues not just in
virtue of my physical features but in virtue of some of my nonphysical
features -- namely the experiences themselves" (Chalmers
1996, p. 198). In supplying non-causal relations to support the claim
to knowledge of experiences, this view disconnects the knowledge
question from the question of how things stand causally, and thus
avoids the self-stultification argument.



A third response to self-stultification begins with the observation
that terms for sensory qualities (words for colors, flavors, pitches
and timbres, etc.) must be learned. Very plausibly, this learning
depends (a) on correlations between properties of present objects and
production of words for those properties by surrounding adult
speakers; and, consequently, (b) on correlations between brain event
types that are caused by the properties of those objects, and brain
event types that are caused by the hearing of adults' words. It
also plausibly depends (c) on the brain's sensitivity to the
correlation of brain events in (b). It is part of epiphenomenalist
theory that the first brain events mentioned in (b) include causes of
sensations of characteristic kinds, and that, after learning, those
same brain events causally determine the production of predicates in
sensation reports. The combination of these relations ensures that, so
long as conditions in the brain are normal, a report of a sensation is
guaranteed to correctly identify the kind of sensation that is
normally caused in the speaker by objects that are standardly
described by the predicate in the report. This guarantee underwrites a
claim to knowledge of what kinds of sensation we are having.



Conditions may, of course, sometimes be abnormal. But that cannot be a
defeater for epiphenomenalist knowledge of our sensations, because all
views must allow for the possibility of cognitive breakdowns such as
unnoticed slips of the tongue or linguistic difficulties brought on by
disease.



In a 2006 paper, Michael Pauen has given a particularly persuasive
argument that offers a new and deeper twist to the problem of what
epiphenomenalists can consistently claim to know about qualia.
Pauen's focus is on the epiphenomenalists' claim that
there are laws linking the occurrence of neural events of certain
kinds with occurrences of qualitative events. Since epiphenomenalists
deny the identity of qualia and physical properties, such laws are not
only contingent, but independent of physical laws. Thus,
epiphenomenalists must concede the possibility of worlds in which the
physical laws are as they are here, but there are no laws connecting
physical events to qualitative events. If such worlds are possible, we
might actually be in such a world, and so the epiphenomenalist can be
asked to provide evidence that we are not in such a world. But the
epiphenomenalist denial of efficacy for qualia precludes the
possibility of providing any such evidence. Even conceding that we
know at each moment what qualia we are having, we cannot exclude the
possibility that our memories seem to tell us of qualitative events
that never occurred (or that were of different kinds than we seem to
remember); yet we would have to rely on such memories in order to have
evidence of causal laws holding between physical and qualitative
events. (Another argument that turns on memory is given in Swinburne
2011.)



Alexander Staudacher (2006) has given a critical discussion of
Pauen's paper. Among several points, perhaps the strongest is a
comparison between Pauen's challenge and the challenge to prove
I am not a brain in a vat. Inability to decisively answer this latter
challenge is not generally taken to impugn our knowledge concerning
tables and chairs, nor are physicists expected to lay it to rest
before proceeding with their science. Analogously, it may be that
worlds without causal laws are not "relevant alternatives"
for epiphenomenalism, i.e., not alternatives that epiphenomenalists
are fairly required to rule out. Staudacher points out that if we are
allowed to raise skeptical challenges of the kind Pauen raises, it
will be possible to construct analogous, unanswerable skeptical
challenges for interactionism. And, although Staudacher does not
provide an analogous case for physicalism, it seems that parallel
difficulties are constructable. For example, according to physicalism,
it would seem to be a conceptual possibility that qualia are
identical, not with neural properties, but with a combination of
neural properties and phases of the Moon, while memory traces depend
only on neural properties. For reasons parallel to Pauen's, it
seems we could never have evidence that would rule this possibility
out. But it is not clear that physicalists need to admit the necessity
of providing evidence against such a view, in order to responsibly
affirm their view. If that is right, parallel reasoning may be able to
support Staudacher's way of resisting the force of Pauen's
challenge.



J. Megill (2007) has raised a problem for epiphenomenalism based on
the assumption that properties must be individuated by their causal
relations. Since epiphenomenalists deny efficacy to phenomenal
qualities, the only causal relations to which they could appeal to
individuate them would be causes of events with those qualities.
However, different causes may produce the same effect. Thus, appeal to
difference of causes alone is an insufficient basis for individuation
of phenomenal qualities.



Epiphenomenalists can be expected to deny the necessity of causal
relations for individuation. They may consistently hold, for example,
that the unique hues are qualities that simply differ and have no
metaphysical need for a principle of individuation. An epistemological
problem, however, may appear to remain: How can epiphenomenalists know
that they experience different phenomenal qualities? This, however, is
the self-stultification problem in a different guise, and
epiphenomenalists can refer to the responses already considered.


## 3. Arguments in the Age of Materialism



One might have thought that if the mental and the physical are
identical, there could be no room for epiphenomenalistic questions to
arise. Behavior is caused by muscular events, and these are caused by
neural events. Mental events will be identical with some of these
neural events; so whatever effects these neural events have will be
effects of mental events, and mental events will make a causal
contribution to, i.e., will "make a difference" to our
behavior.



Questions about epiphenomenalism, however, arise the moment any
distinction is made between the mental properties and the physical
properties of an event. Section 3.1 will explain three ways in which
this can be done within a broadly materialist monism. The third of
these ways is still the subject of lively debate, and some of the
issues will be explained in sections 3.2 and 3.3.



It should be noted that most recent writers take a somewhat dogmatic
position against epiphenomenalism. They presume that epiphenomenalism
is to be avoided, and they go to great lengths to try to show that
they have avoided incurring that anathema, despite maintaining the
sufficiency of physical causation in conjunction with some kind of
distinction between the mental and the physical.


### 3.1 Three Routes to Puzzlement: Externalism, Anomalous Monism and Realization



(1) Many philosophers hold an *externalist* view of
intentionality, according to which intentionality requires
representation, and representation depends on circumstances external
to the body of the representing subject. (To illustrate with
Putnam's (1975) famous example from Twin Earth, what a thought
that \(S\) might express by "This is water" is actually
about depends on what the transparent, tasteless liquid in
\(S\)'s environment actually is.) It seems, however, that the
causal determinants of \(S\)'s behavior can depend only on
events occurring inside \(S\)'s body. Thus, if externalism is
right, what \(S\) does cannot depend on the intentional content of
\(S\)'s thoughts.



This conclusion is compatible with holding that a proper
*description* of \(S\)'s behavior should refer to
circumstances external to \(S\). For example, describing \(S\) as
*reaching for a glass of water* may not be appropriate unless
\(S\) believes the glass contains water; and that this is what \(S\)
believes may depend on circumstances external to \(S\). But then, it
is at least tempting to conclude that it cannot be the intentional
character of \(S\)'s belief that is causing the extension of
\(S\)'s arm toward the glass. After all, \(S\)'s
twin-earth double has, in some sense, a different belief (one that
refers to XYZ) but the internal bodily story of the causation of the
double's arm-extension will be exactly the same as the story for
\(S\) (up to substitution of XYZ in the double's body wherever
\(S\) has an H2O molecule).



(2) Donald Davidson's (1970) anomalous monism held that (i) each
mental event is identical with a physical event, but (ii) there are no
psychophysical laws. Davidson accepted the view that causation
involves laws and, in view of (ii), held that the laws into which
mental events entered related physical properties (or, mental events
under their physical descriptions). Many philosophers regarded this
view as tantamount to epiphenomenalism, i.e., to the view that
causation of our behavior involves only the physical properties of our
parts, and that the mental properties as such have no efficacy.



(3) A similar discussion rages today, but begins with a background
assumption of multiple realization. It is thought to be highly
implausible that belief in a particular proposition, or desire for a
particular state of affairs, is identical with the same state of a
brain (or a part of a brain) in different people, or even in the same
person at different times. Instead, the same belief or desire is taken
to be "realized" by different neural structures or states
of activation on different occasions.



Since the physical properties of different neural events are
different, transitivity of identity prohibits claiming identity of
mental properties with any of the physical properties whose
instantiation realizes those mental properties. In a body of work
stretching over many years, Jaegwon Kim (e.g., 1993, 2005) has argued
that this division of mental from physical properties leads to
exclusion of mental properties from playing a causal role. After all,
it is widely accepted that the physical properties of neural events,
together with a person's state of neural connectivity, are
sufficient to produce later neural events. Since behavior depends on
muscle contractions that depend on neural innervation, it seems that
physical events and structures, and the physical laws that apply to
them, are quite enough to bring about our behavior. There is nothing
left for mental properties to do.



There are, of course, some cases in which there is more than one
sufficient cause of an event. Caesar's death seems likely to
have been overdetermined, i.e., it is probable that more than one
attacker's stroke would have been sufficient by itself for his
death. But instances of mental properties are not distinct from
instances of physical properties that are their realizers in the way
that stabbings are distinct from each other, and systematic
overdetermination of our behavior is generally regarded as
implausible.


### 3.2 Responses to Exclusion Arguments



Many writers have held that Kim-style exclusion arguments depend on an
understanding of causation for which there are preferable
alternatives. (See, e.g., Woodward 2008, 2017; Kroedel 2016; Beebee
2017.) This kind of response is sometimes put forward as providing a
more correct account of causation. Other writers allow that exclusion
arguments can succeed if causation is understood as productive (or
'oomphy') causation, but hold that there are other
"conceptions of causation" (Beebee, 2017) on which it
remains acceptable to say that our mental states cause our behavior.
Epiphenomenalists may concede that there is some such sense, but still
think their view is vindicated if all the productive causation is
provided by the physical activities of our brains.



Epiphenomenalists may also emphasize that examples in exclusion
arguments are usually beliefs, desires or intentions. These mental
properties are closely associated with behavioral dispositions, and
can easily be understood in functional terms for which multiple
realizability is immediately plausible. As Kim (1993, 366) has
explicitly recognized, however, there are properties that have long
caused difficulties for functionalism, namely, the qualities of
phenomenal experiences such as pains, itches, tastes, smells,
afterimages, and so on. The "explanatory gap" (Levine
1983) or "unintelligibility" (Robinson 1982a) or the
"hard problem" (Chalmers 1996) concerning the connection
between neural events and phenomenal qualities can be otherwise
expressed as our inability to see any necessity in that connection. We
are unable to understand why it should be that a series of neural
activations occurring in various degrees of intensity and temporal
relations should always be accompanied by pain, or itch, or, indeed,
by any phenomenal quality whatever. Inability to see any such
necessity is, of course, not a proof that such a necessity does not
obtain. Nonetheless, absent insight into the necessity of the
connection between neural properties and qualitative properties, we
are arguably in an *explanatory* position similar to
traditional epiphenomenalism. That is, we will have a sufficient
explanation of behavioral reactions to stimuli that invokes
exclusively neural properties. In addition, we may hold the view that
these neural properties are necessarily connected to qualitative
properties; but, lacking explanation of this necessity, this
connection will contribute no understanding of how qualitative
properties could make a difference to behavior. Because this
difficulty has not been removed in the case of qualia, the success or
failure of the previously discussed Traditional Arguments remains
relevant to contemporary thinking about epiphenomenalism.


### 3.3 Mental Properties and Distinctive Causal Powers



L. A. Shapiro and E. Sober (2007) have developed an alternative line
of argument that they hold to apply just as well to functional
properties and properties that resist functional analysis. The
distinction between common causation and realization plays a key role.
Common causation, they note, can lead to an empirically based denial
that one co-effect causes another. For example, tail length in mice
offspring is caused by their parents' genes, not by their
parents' tail length -- and this can be empirically shown
by cutting parental tails (which, of course, leaves their genotype
constant) and observing no effect on tail length of offspring.



It is impossible, however, to suppress a realized condition while
leaving its realizer constant, so there is no sense to the demand that
beliefs should have causal powers that are additional to the causal
powers of their neural state realizers. Nor is it possible to suppress
a phenomenal quality while holding constant a state with its
(allegedly) identical neural property. Thus, saying that "there
is nothing left for the property of being a belief (or a phenomenal
quality) to do, once the neural realizer (or identical neural
property) has done its work" does not undercut the efficacy of
the beliefs or phenomenal qualities. It shows only that beliefs (or
phenomenal qualities) do not satisfy a demand (for an
'extra' causal contribution) that is incoherent in
itself.



J. A. Baltimore (2010) has responded by arguing that there are reasons
other than that illustrated by the mice tails example for denying
efficacy to mental events. M. Baumgartner (2010; see Woodward, 2015
for response) suggests that Shapiro and Sober's approach depends
on a certain (interventionist-inspired) view of causation, but that
attributions of causation in virtue of mental properties cannot be
counted as making sense without departing from the terms of that view.
Whether this strong critique is accepted or not, it is evident that
removing a reason for objecting to efficacy of mental events in virtue
of their mental properties does not by itself provide a positive
reason for asserting such efficacy.



Such a reason may, however, be found in the subset view proposed by
Shoemaker (2007). To briefly illustrate a key idea, suppose that a
certain belief, \(M\), can be realized by alternative physical states
\(P\_1, \ldots P\_n\). Suppose further that this belief is involved in
an inference, and that its possessor arrives at a new belief, i.e.,
arrives at another state that has a new mental property, \(M^\*\).
Suppose, finally, that \(M^\*\) can be realized by alternative physical
states \(P^\*\_1, \ldots, P^\*\_o\), and that each \(P\_i\) is a sufficient
physical cause for some \(P^\*\_j\). A particular \(P\_i\) causes a
particular \(P^\*\_j\) by a particular causal route that need not be
shared by other \(P\) to \(P^\*\) instances, and so \(P\_i\) has causal
powers not shared by all instances of M. But any instance of \(M\)
would have been realized by a sufficient cause of some realizer of
\(M^\*\). Thus, \(M\)'s causal powers include just those that are
relevant to bringing about \(M^\*\) (assuming that other conditions,
e.g., belief in other premises required for the inference, are held
constant). Given these assumptions, it is reasonable to conclude that
it is \(M\) rather than its particular realizers that causally
contribute to \(M^\*\), even though each instance of \(M\) is realized
by some \(P\_i\) that is a sufficient cause of a realizer of \(M^\*\),
and thus is sufficient for \(M^\*\).



The subset view is the subject of lively debate; see, e.g., Antony
2010, Audi 2012, Melnyk 2010, Shoemaker 2010. One objection is
that the subset view assumes rather than shows that M has any causal
powers at all, and that this is the key question at issue (Kim 2010).
Reasons have been offered for doubting this assumption, i.e.,
accepting epiphenomenalism, at least for beliefs and desires. Segal
(2009) argues that being a belief and being a desire are dispositional
properties, and that dispositional properties are not efficacious.
Tammalleo (2008) supports an exclusion argument, and invokes
mechanisms independently established by cognitive psychology to
explain why we have the mistaken intuition that mental states are
causes.


### 3.4 Epiphenomenalism and Intrinsic Properties



Frank Jackson (1982) has given an epiphenomenalistic argument that has
spawned lively responses from many quarters. This argument turns on
the concept of physical information, where "physical
information" is information about ourselves and our world of the
kind that is obtainable in the physical, chemical, and biological
sciences. In Jackson's argument, a brilliant scientist, Mary,
has learned all the physical information there is about color vision.
Having been confined to a black and white room, however, Mary has
never had a color experience. Jackson asks whether Mary will learn
anything when she is released from her confinement and thus comes for
the first time to have color experiences. It seems compelling that she
would learn something; but as she already has all the physical
information there is, what she learns must be some other kind of
information, which we may call "phenomenal information".
This "knowledge argument" has been regarded as a strong
reason to accept a dualistic view of our experiences. When combined
with the traditional arguments (Pro) given above, it becomes a potent
source of support for epiphenomenalism.



David Lewis (1988) undertakes a thorough response to the knowledge
argument. Among Lewis's many considerations, there is one that
seeks to enforce a connection between phenomenal information *per
se* and epiphenomenalism. According to Lewis's argument,
even if one says that phenomenal *events* are identical with
physical events, and even if one says that phenomenal events produce
physical effects in violation of physical laws, one will still be led
to a form of epiphenomenalism if one says there is phenomenal
information that is irreducibly different from physical information.
To put the argument in ruthlessly summary form, let \(V\_1\) and
\(V\_2\) be two possibilities for the phenomenal information that one
acquires by, and only by, tasting Vegemite. Suppose that \(P\_1\) is a
physical state produced by the taste of Vegemite. That the taste of
Vegemite has this physical effect is a piece of physical information.
But this same physical information is compatible with two
possibilities, (a) \(V\_1\) is related by a law, \(L\_1\), to \(P\_1\);
and (b) \(V\_2\) is related by a different law, \(L\_2\), to \(P\_1\).
Now, either of these possibilities is compatible with all the physical
information we have; i.e., their difference makes no physical
difference. Thus, that the phenomenal information in the taste of
Vegemite is, say, \(V\_1\) rather than \(V\_2\) can make no difference
to anything physical, i.e., \(V\_1\) is epiphenomenal. Lewis's
point here is not to argue for or against epiphenomenalism; rather, he
assumes epiphenomenalism is false, and uses the fact that the
hypothesis of phenomenal information leads to it as an argument
against that hypothesis.



Denis Robinson (1993) raises the possibility that Lewis's
argument can be extended to produce a far-reaching and puzzling
result. Suppose that \(I\_1\) and \(I\_2\) are two possibilities for an
*intrinsic* property of a basic physical entity, e.g., a quark.
Everything relevant to physics can be expressed by the lawlike
relations in which quarks stand to fundamental physical objects and
properties. Let this set of relations be \(\mathbf{S}\). It appears
that there are two possibilities, (a) \(I\_1\) is related by a set of
laws, \(\mathbf{L\_1}\), to \(\mathbf{S}\); or (b) \(I\_2\) is related
by a different set of laws, \(\mathbf{L\_2}\), to \(\mathbf{S}\).
Either of these possibilities is compatible with all the physics we
have, i.e., their difference makes no physical difference. Thus, that
the intrinsic property of quarks is, say, \(I\_1\) rather than \(I\_2\)
can make no difference to physics, i.e., \(I\_1\) is epiphenomenal. The
generalization of this point is that the intrinsic properties of the
fundamental objects of physics must be epiphenomenal.



It thus appears that we must either (1) deny that fundamental objects
of physics have any intrinsic properties, or (2) deny that
Lewis's argument for the connection of phenomenal information
with epiphenomenalism is sound, or (3) deny that Lewis's
argument can be paralleled in the suggested way for the case of
intrinsic physical properties, or (4) admit an epiphenomenalism of
intrinsic properties into our view of the basic structure of physical
reality.



Bertrand Russell (1927, 382) held the view that physical theory can
reveal only causal structure, or "formal properties" of
matter, and that "by examining our percepts we obtain knowledge
which is not purely formal as to the matter of our brains." This
idea is taken up sympathetically (with substantial reworking in a
quantum mechanical context) by Lockwood (1993). Chalmers (1996)
offered a useful discussion of the view (now known as
"Russellian monism"), and expressed some sympathy for it
-- a sympathy which has increased in intervening years (see,
e.g., Chalmers 2010). Denis Robinson (1993), however, regards
intrinsic similarity of fundamental physical entities as different
from similarity of phenomenal properties.



If phenomenal properties are intrinsic properties of fundamental
physical objects, and the latter stand in lawlike relations, then
lawlike relations will hold between phenomenal properties and some
physical occurrences. This conclusion appears to give a causal role to
phenomenal properties and thus to suggest a way out of
epiphenomenalism. But if intrinsicality carries epiphenomenality, as
D. Robinson's extension of Lewis's argument suggests, then
this way out of epiphenomenalism would be blocked. Moreover, since
there is no phenomenal quality that we are always experiencing, no
instantiation of a quality by a fundamental physical particle can, by
itself, be one of our sensations. It is thus not clear that Russellian
monism gives any more causal role to our sensations than does
epiphenomenalism (see Robinson 2018 for elaboration).


### 3.5 Empirical Considerations



There are some empirical results that engage epiphenomenalism in
several ways. These empirical results do not cut as deeply as the
foregoing arguments, for they do not claim to show that consciousness
is completely inefficacious. In particular, they do not show, and are
not aimed at showing, that episodes of consciousness do not causally
contribute to reports of such episodes. They suggest instead that the
reported consciousness is not causally related to our nonlinguistic
behavior in ways that we ordinarily suppose.



An early and very well known argument derives from the work of B.
Libet (1985, 2004). Libet asked participants in his experiments to
make an unplanned movement when they felt the urge to do so, and to
report (using a specially designed clock-like instrument) the time
when they felt the urge to move. Recordings of participants'
brain waves were made during these experiments, and Libet found a
signal (the "readiness potential", RP) that correlated
with the movements. The key finding was that (after allowing for
corrections due to neural transmission times) the RP occurred about
350 ms earlier than the time that participants reported having the
urge to move. Libet himself allowed for the possibility of a veto
after the urge that would block the movement. However, many have drawn
an implication that the conscious urge to make a movement comes too
late to causally contribute to a movement that has already been
initiated by brain processes (that were detected by the RP
measurement). A corollary of this implication is that, to the extent
we have an intuition that our urge to move caused the movement, we are
subject to a causal illusion. The possibility of causal illusion, in
turn, weakens the intuitive argument against epiphenomenalism
explained in section 2.1 above.



More recently, work led by J-D. Haynes (2013; see also Soon, *et
al*. 2008) has found brain events that are somewhat correlated
with decisions, and that occur several seconds before the decision is
made. This work seems unsettling for the following reason. If we
believe we were weighing options on a matter that was still open at,
say, one second before our conscious decision, but our action was
already predictable from neural events before that, then we would be
under some illusion about the extent to which our conscious decision
has an effect on our behavior.



Work by Wegner and Wheatley (1999), Wegner (2002), and Linser and
Goschke (2007), describes participants who have judged themselves to
have partial control of movements over which they in fact lacked
control. But if we can demonstrably have illusions about being in
control, our sense of being in control of our actions cannot be taken
as evidence that our conscious intentions actually have effects in our
(nonlinguistic) behavior. Such illusions further imply that we
sometimes lack knowledge of the actual course of causation of our
actions. (For discussion of conscious control, see also Oakley and
Halligan 2017.)



In well-regarded studies, Nisbett and Wilson (1977a, 1977b) showed
that people sometimes confabulate, that is, they give reasons for
evaluative judgments that do not reflect the actual causes of making
those judgments. This work again carries two implications: that people
are sometimes mistaken in accepting efficacy of what they believe to
be their reasons for a judgment, and that they are sometimes mistaken
about the real reasons for their behavior.



The implications drawn from these experiments have been criticized on
several grounds. In some cases, there are technical criticisms of
methods or statistical analyses (see Dennett, 1991 for critique of
Libet's conclusions, and S. Walter's 2014 discussion of
the Wegner and Wheatley (1999) experiment; for defense of Libet see
Bonicalzi and Hggard, 2019.). The force of the work led by Haynes is
mitigated by the fact that predictions of behavior from several
seconds before its occurrence, while statistically significant, are
far from perfect. Many other points have been made (see Nahamias
2008; Mele 2014; Shepherd 2017; Baumeister *et al*. 2018).
Two basic criticisms are offered by many writers. First, many of the
experimental conditions involve meaningless setups (ouija-like boards,
for example) or meaningless decisions (e.g., when to move a finger or
which of two buttons to press) that bear little resemblance to
real-life decisions (e.g., whether to accept a job, or go to a
particular place for a vacation) where people bring substantive
reasons and personal preferences to bear. These oddities and
simplifications may be thought to render ineffective psychological
mechanisms that would be operative in more realistic cases and that
would forestall illusions about the relation between our consciously
entertained reasons and our behavior. Second, the fact that there are
some cases in which unconscious influences have a noticeable effect on
our behavior does not show that we are never, or even not usually,
acting in a manner that would be rational, given our particular
longstanding beliefs and preferences.


## 4. Historical Note on Automatism and the Term "Epiphenomenalism"



James Ward's *Encyclopedia Britannica* (tenth edition,
1902) article, "Psychology", contains the following
summary of T. H. Huxley's view: "physical changes are held
to be independent of psychical, whereas psychical changes are declared
to be their 'collateral products'. They are called
*collateral* products, or 'epiphenomena' to obviate
the charge of materialism ... ." McDougall (1911) roundly
declares, referring to Huxley, that "to him [the doctrine] owes
the name by which it is generally known; for he it was who suggested
that the stream of consciousness should be called epiphenomenal, or
the epiphenomenon of the brain-process." In Carington (1949), H.
H. Price expresses his belief that the term
"epiphenomenalism" was introduced by T. H. Huxley.



It is interesting, therefore, that the term
"epiphenomenalism" does not occur in Huxley's (1874)
essay on our topic; nor have I been able to find it elsewhere in his
published work. (Neither does Huxley use the terms "stream of
consciousness" or "brain-process".) Of course, it is
possible that Huxley made oral use of "epiphenomenalism"
in lecturing. This seems unlikely, however, as he had at his disposal
another brief term for the view he was concerned to promote, the
meaning of which would have been more immediately accessible to most
audiences, namely, "automatism". This is the term that
occurs in his 1874 essay, which bears the title "On the
Hypothesis that Animals are Automata, and its History". Besides
containing the analogy of the steam-whistle that contributes nothing
to the locomotive's work, this essay compares consciousness to
the sound of the bell of a clock that has no role in keeping the time,
and treats volition as a symbol in consciousness of the brain-state
cause of an action. As Ward correctly noted, nonefficacious mental
events are referred to in this essay as "collateral
products" of their physical causes. The essay is not solely
concerned with animals: to the best of Huxley's judgment,
"the argumentation which applies to brutes holds equally good of
men".



Huxley and his contemporaries seem to have been impressed by
preparations in which frogs had had various portions of their brains
removed. Reasoning by analogy with humans lesioned by disease or
battle, Huxley finds it plausible that the frogs are not conscious, or
not exercising volition; yet when thrown into water, for example, they
swim just as well as undamaged frogs. Huxley also discusses at some
length the case of a Seargent F., who had sustained a shot that
fractured his left parietal bone. Once or twice a month, this soldier
would have a day-long bout in which he exhibited complex behavior
(e.g., singing, writing a letter, "reloading",
"aiming", and "firing" his cane with motions
exactly appropriate to a rifle in a skirmish) while being plausibly
unconscious, as evidenced by insensitivity to pins and shocks, sound,
smell and taste, and to a great extent, vision. Huxley allows that
there can be no direct evidence showing that the soldier is conscious
or not conscious; but he concludes that he may be devoid of
consciousness, while performing his complex and apparently purposeful
movements.



Huxley was not alone among 19th century figures who gave vigorous and
clear expositions of an epiphenomenalistic view. S. Hodgson (1870), W.
K. Clifford (1874) and H. Maudsley (1886) were exponents of the view.
Romanes' posthumous (1896) contains an excellent statement of
the view, which was first published in the early 1880s; and William
James (1879) likewise offers an early clear statement of it. Both
Romanes and James follow their statements of the view with arguments
against its acceptance.



None of the works just mentioned include the term
"epiphenomenalism". I have located three articles in
*Mind* in the 1890s that do use the term (the earliest, in
1893, hyphenates it as "epi-phenomenalism"). The earliest
occurrence of the term for referring to automatism that I have been
able to locate is in William James's *The Principles of
Psychology*, first published in 1890. It occurs in his chapter
"The Automaton-Theory" once, in scare quotes; the rest of
the time, the view is referred to as the
"automaton-theory" or the "conscious
automaton-theory". James attributes the origination of the view
to Shadworth Hodgson, in *The Theory of Practice* (1870). A
section of this work titled "Dependence of consciousness on
nerve movement" does indeed contain a forthright statement of
the view (without "epiphenomenalism",
"automatism" or any other "-ism" tag).



Early in his discussion of automatism, James (1890) includes some
remarks about his intellectual development, and refers to his early
study of medicine. "Epiphenomenon" has a use in this
field, meaning a symptom concurrent with, but not causally
contributory to, the course of a disease. Some early twentieth century
dictionaries list only this meaning of the term; by mid-twentieth
century, the focal philosophical meaning is standardly given. My
present surmise is that the term "epiphenomenalism" came
into philosophy from medicine in the late nineteenth century,
possibly, though less certainly, through William James's use of
the term in his influential *Principles of Psychology*
(1890).