(published in Journal of Consciousness Studies, vol 18, no 3-4, 2011, pp.196-216.)
Could anyone justifiably believe epiphenomenalism?
Richard Swinburne
ABSTRACT: Epiphenomenalism claims that all conscious events are caused immediately by brain events, and no conscious events cause brain events. In order to have a justified belief in a theory someone needs a justified belief that it or some higher-level theory predicts certain events and those events occurred. To have either of the latter beliefs we depend ultimately on the evidence of apparent experience, memory, and testimony, which is credible in the absence of defeaters; it is an undermining defeater to a belief produced by apparent memory that it was not caused by a past belief, and to a belief produced by apparent testimony that it was not caused by an intention to say what the speaker believes. A justified belief in epiphenomenalism requires either evidence about when conscious events occurred or evidence about what some theory that brain events are caused solely by physical events predicts, but epiphenomenalism rules out the availability of the evidence of apparent memory and testimony on these matters. Hence only a rare individual scientist who could hold in her mind at one time the proof that a theory makes certain predictions could have a justified belief that epiphenomenalism is true. It follows that recent neurophysiological work in the tradition of Libet has no tendency whatever to provide a justified belief in epiphenomenalism.
I Introduction
I understand by ‘epiphenomenalism’ the theory that [X] all conscious events have physical events (viz. brain events) as their only immediate causes, and [Y] no conscious events cause physical events.1. By one event causing another event ‘immediately’ I mean the first event causing the second event without doing so by causing some third event which in turn caused the second event. As a theory about what kinds of events cause other kinds of events, epiphenomenalism must be regarded as a scientific theory. Hence this theory cannot be justifiably believed by someone without their justifiably believing that it makes true predictions(checkable without presupposing the truth of that theory) not predicted by serious rival theories, or is a consequence of some higher-level theory which makes true predictions not made by serious rival theories2. This will hold on any mildly plausible internalist or externalist account of justification. The internalist will regard successful prediction as an a priori requirement for justification, while the externalist will hold that the scientific method requiring successful prediction is a reliably truth-conducive method (or satisfies some other externalist requirement) and that that is what makes a belief acquired by that method justified3. I argue in this paper that (with a very small exception) no one could ever have this justification for epiphenomenalism4.At the end of the paper I apply my general results to show that experiments of the type pioneered by Benjamin Libet could not yield that justified belief in epiphenomenalism.
II Ontology
Epiphenomenalism assumes event dualism; that there are both physical events, including brain events, and mental events.There are different ways for a dualist to make the distinction between mental and physical events. Since all who accept thedistinction think of sensations as mental events, definitions of the mental in terms of the intentional are clearly inadequate, and so I suggest that the distinction is best made in terms of the private versus the public.I define a mental event as an event of a kind to which the person involved in the event has privileged access, that is a way of access to whether an event of this kind is or is not occurring which is necessarily not available to others, by actually experiencing it or its absence. I define a physical event as an event to which no one person has privileged access, that is a public event. I define a pure mental event as one which does not entail the occurrence of a physical event. Perceptions such as my seeing a tree are mental events since I can know better than anyone else whether or not I am seeing a tree, but they are not pure mental events since seeing a tree entails that there is a tree present – and that is a physical event. But sensations such as pains and beliefs such as the belief (of which I am currently aware) that I am seeing a tree are pure mental events, since it is not entailed by the occurrence of sensations or beliefs that anything public is happening.5
Conscious events are a sub-class of pure mental events. They include both those pure mental events which exist only while the subject is conscious of them, and also pure mental events of which the subject is conscious but which may exist while the subject is not conscious of them. The first group includes not merely sensations such as pains, but also occurrent thoughts. If I am not in any way aware that the thought ‘today is Thursday’ is now crossing my mind, it isn’t crossing my mind. Among the pure mental events of which I can become conscious but which may continue to exist while I am not conscious of them are beliefs, desires, and intentions (in the sense of intentions or purposes currently directing my actions). I have innumerable beliefs of which I am not currently thinking, and may be fulfilling some intention (e.g. to walk to the railway station) while thinking about quite other matters.Yet I may become conscious of my beliefs (e.g. when I investigate them), desires, and intentions (especially when I form a new intention, that is make a decision).
Many philosophers have held that talk about beliefs and intentions is analysable in terms of talk about public actions or the brain events which cause them. But that cannot be correct, since intentions only lead to public actions when combined with beliefs. Different combinations of beliefs and intentions may lead to the same public actions. You have a headache, and ask for an aspirin, I give you a pill; it is a poison pill and you are poisoned and die. My action may be the result of a belief that the pill was an aspirin and my intention to cure your headache; or the result of a belief that the pill was poisonous and my intention to kill you. Of course we can often make good inductive inferences from someone’s past behaviour and public life experiences to the intentions and beliefs which it is most probable that he will have had; but that is compatible with him suddenly forming a new intention (e.g. to kill someone) or forgetting a belief (that the pill was poisonous), and clearly the agent has a way, while he is doing the action, of knowing about what his intentionis and so whether he has some requisite belief, not available to others.As a theory about conscious events, epiphenomenalism must be regarded as concerned withall such events insofar as the subject is conscious of them.
III Epistemology
How can anyone have a justified belief that a scientific theory predicts certain events?
Scientists in the centre of the field will have calculated that it makes these predictions. And if a scientist can hold all the calculations in her mind at one time, it will be for her a deliverance of reason, evident a priori, that the theory does make these predictions. Alas, for any scientific theory of any complexity most experts at the centre of the field will be unable to hold in their minds at one time all the relevant calculations; even as the scientist reads through the text of her calculations, she depends on her memory towards the end of the calculations for her belief that the initial calculations were correct. Later in life all that she may remember is that it did seem to her earlier that the theory made those predictions. She may have a diary in which she recorded this, which will be – as it were – her testimony about this to herself and others. Non-scientists and scientists less central in the field will depend on the testimony of those whom they regard as experts, that they have made those calculations. So what makes a belief that the theory predicts certain events justified is experience (of ‘seeing’ that the calculations are current), memory, and testimony; or rather, since all of these sources may be mislead, it is apparent experience, memory, and testimony. These three sources provide our evidence that the theory makes true predictions. True, we do not normally speak of someone’s apparent experience of the truth of calculations, or their apparent memory or testimony that they made certain calculations which seemed to them correct showing that the theory predicts certain events, as part of the ‘evidence’ for the correctness of the theory. But we do in fact rely on these sources for the justification of a belief that a theory predicts certain events, and –as we shall see shortly – any evidence undermining the belief that the apparent experience, memory, or testimony was veridical will undermine the justification of the theory6. So in a wide sense of ‘evidence’, everyone requires apparent experience, memory, or testimony of this kind as part of the ‘evidence’ which will give them a justified belief that the theory is true.
And how can anyone have a justified belief that the events predicted in fact occurred? Someone will normally depend on the evidence of the same three sources. Certain observers will (apparently) in a wide sense experience these events – that is if they are physical events, they will perceive them, or if they are conscious events they will experience them. (I will use the wide sense of ‘experience’ to include perception in future.) Later, the observers may (apparently) remember having experienced the events; and others will depend on the (apparent) testimony of observers about these (or the observers may depend on their own apparent written testimony.) Alternatively, a believer may have a justified belief that the events predicted occurred because it is a consequence (deductive or probabilistic) of some other justifiably believed theory that they did. But in that case a justified belief in that other theory would itself depend on the evidence of the same three sources.
It is a fundamental epistemic principle that what we seem to (that is, apparently) experience is probably so – barring counter-evidence; this includes what we seem to observe in the public world, what we seem to experience as conscious events, and the logical consequences we seem to ‘see’. This has been called the principle of credulity. If this were not a fundamental epistemic principle, total scepticism would follow. It is a second fundamental epistemic principle that what we seem to (that is, apparently) remember having experienced, we probably did experience - barring counter-evidence. And it is a third fundamental epistemic principle that what people seem to be (that is, apparently are) telling us that they experienced, they probably did experience, again barring counter-evidence.7 Beliefs acquired by apparent experience, memory, and testimony are probably true – in the absence of counter-evidence. Science relies on the applicability of these principles to determine what constitutes evidence. A scientist takes his (apparent) observations, experiences and calculations as probably correct, at least when he has looked carefully and checked. Almost all scientific knowledge relies on (apparent) memory (e.g. of the results of experiments or calculations only written up the following day). And for all science, we all rely most of the time on the (apparent) testimony (written and spoken) of observers to have had certain experiences (normally in the form of observations) and of theoreticians to have done certain calculations. And the wider public relies entirely on the (apparent) testimony of scientists with respect both to their calculations and to their experiences.
Beliefs acquired by apparent experience, memory, and testimony are however open to counter-evidence or defeaters. There are two kinds of defeaters– undermining and overriding defeaters. If we have inferred the occurrence of some event y from present evidence x, then an undermining defeater is evidence (making it probable) that x did not occur or is not good evidence for y, whereas an overriding defeater is new evidence that y did not happen. If for example I apparently experience hearing my telephone ring, and then someone points out to me that the noise is coming from the television set where someone is depicted as hearing a telephone ring, that constitutes an undermining defeater for my apparent experience. It doesn’t show that my telephone was not ringing, but it does show that the noise was not evidence that it was, because the noise had a different cause. Again, if I have come to believe that y happened because some person apparently testified that he saw y, evidence that that person was somewhere else at the relevant time and so could not have seen y undermines his evidence, and I no longer have reason to believe that y happened. By contrast the apparent testimony of two independent witnesses that they were at the place of the alleged occurrence of y, and that they saw that y did not happen, overrides the evidence of the original witness. But the evidence constituting the defeater must itself be provided by apparent experience, memory, or testimony. This evidence need not be direct evidence of, for example, the non-occurrence of the event or of the evidence for it – for example in the form of apparent testimony that the testifier was not present at the site of the alleged event; it may be indirect evidence, in the sense that it may be evidence supporting a theory which has the consequence that the event or the evidence for it apparently experienced, remembered or testified to couldn’t have happened - for example, evidence supporting a theory that the testifier was blind and so couldn’t have seen what he testified to having seen.
Scientists are used to their claims about what theories predict and what has been observed being defeated from time to time. Calculations are sometimes shown to have been inaccurate, when others recalculate them many times. Evidence that when the experiment is done again and again, the original result cannot be replicated is evidence that it was originally misobserved or misreported. But, to repeat the point, the evidence constituting the defeater must itself ultimately come from apparent experience, memory, or testimony.
That someone justifiably believes that a theory predicts certain events and that these events were (in the wide sense) experienced, only if they have apparent experience, memory, or testimony (which is not defeated) that these things are so(or it follows from some other theory justified by these three sources) is hard to deny8. This claim is compatible with any mildly plausible account, either internalist or externalist, of what gives apparent experience, memory, and testimony this status. Likewise it is compatible with any view at all about what else (e.g being a simple theory) other than its ability to predict events makes a theory probably true.
Further, I claim, in having beliefs resulting from experience of physical events such as the apparent observation of a desk, we assume that the event (of the presence of the desk) experienced caused the belief (with its accompanying sensations), ‘caused’ that is in being a necessary part of the total cause. In perception we seem in contact with the event apparently observed. That event seems to force itself upon us; the presence of the desk seems to force itself upon me, and so I have no option but to believe that it is there. That, we assume, is because there is a causal chain from the desk to the belief – only causes exert ‘force’. (This holds, we believe these days, because the desk reflects light rays which land on my eyes and cause the belief.) Hence the generally accepted causal theory of perception. (Maybe not any perceptual belief caused by the object apparently observed constitutes an observation of it. Maybe the causal route must not be ‘deviant’. But that does not affect my point that a causal route is necessary for perception.) It is natural to suppose that the same goes for our beliefs about our conscious events; that in believing that we are having certain sensations we assume that the belief is forced upon us by those events, and in believing that our calculations are correct we assume that that belief is forced upon us by the calculations – the marks on the paper or in our mind symbolizing the calculations cause us to have the belief that the calculations are correct.
Some writers have denied that our beliefs about currently experienced conscious events are caused by those events; they claim that in this special case we have direct access of a non-causal kindto our conscious events9. This suggests a qualification on[X] so as to read, instead of ‘all conscious events’, ‘all conscious events except conscious beliefs about current conscious events’. I shall assume this qualification, since if my arguments show (as I believe that they do) that noone could have a justified belief in epiphenomenalism even with this qualification, it will follow that they cannot have it without the qualification.
So with respect to beliefs resulting from experience (with the above mentioned
exception) evidence that such a belief was not caused by a causal chain (of necessary parts of total causes) from the event believed constitutes an undermining defeater for it – as in my example of the telephone ring.