Epiphenomenalism is one idea I’ve struggled with for a long time: to my eyes, it doesn’t make any sense. But more importantly, when applied to philosophy of mind, it seems to me that epiphenomenalism does a great deal of damage. However, I can see that lots of people take the idea seriously, so my contribution is also a call for help: if, after reading my attack, you’ll think you can explain me why I’m wrong, I would really appreciate hearing from you.
I’ve never found the courage to write on epiphenomenalism because I nurture self-doubt, as an explicit epistemological method; in this context, I can see that many people who command my unconditional intellectual respect take the notion as seriously as possible (see for example Chapter 4 in Chalmers’ The Conscious Mind: In Search of a Fundamental Theory – 1996), giving me a strong indirect indication that I must be missing something crucial. I’ve finally decided to write my argument down as a consequence of a long discussion I’ve held on Conscious Entities. In the latter parts of my sparring with Jochen, I’ve realised that all my efforts on Consciousness (see also the Evolutionary Theory of Consciousness draft paper, ETC in short) rely on the assumption that epiphenomenalism is nonsensical. If you take away this assumption, ETC becomes a much weaker hypothesis, on a priori grounds.
In particular, Jochen noted that I’ve dismissed epiphenomenalism in a way which is “much (much!) too quick“. I think he’s right, and will try to make amends with what follows.
My argument is organised in two parts, first I explore the notion of epiphenomenon in general, along with why it has no place in the kind of scientific epistemology I’ve been pursuing here. In the second part I’ll look at how the concept is applied to the mind-body problem, or philosophy of mind in general. Overall, I’ll argue that the whole idea is irredeemably flawed and unquestionably harmful when applied to minds.
Epiphenomena in general.
According to the Merriam-Webster, the definition of epiphenomenon is (emphasis added):
A secondary phenomenon accompanying another and caused by it; specifically: a secondary mental phenomenon that is caused by and accompanies a physical phenomenon but has no causal influence itself.
My thesis in short. if something has no causal influence at all, none whatsoever, then:
- We have no way of knowing it exists,
- We have no interest in knowing if it exists,
However, the final conclusion is that declaring that something is an epiphenomenon (in the strong sense) is equivalent of declaring it non-existent, on epistemological grounds. I must add that there is a weak version of the concept: one where an epiphenomenon is a secondary phenomenon which has very weak causal powers (with respect to the powers of what causes it), or, in formal scientific subjects, it has causal effects only outside the field of interest. I have absolutely no problem with weak epiphenomenalism. I don’t think it’s a particularly useful concept, for comparing causal prowess looks a little pointless to me, but I certainly see no fundamental flaw in the general idea.
Before expanding on my position, it’s worth restating a few general considerations about what is amenable to scientific enquiry: science is in the business of identifying causal relations between observable phenomena. It usually relies on quantitative measures because very little in the world is binary (either present or absent, on and off, and so forth). The much trusted idea of falsifiability enters the picture because when a causal relation is hypothesised and quantified, it becomes possible to make predictions: put A and B together and they will do nothing at all, boil them up, or add this catalyst, and they will form X amount of C with a small Y residue of D. With such predictions, you can test if your hypothesised causal relation does hold, and if it does, you’ll be able to reliably produce substance C. If you don’t get the expected results and you are reasonably confident that there is no flaw in your experimental procedure, then your theory about the causal relation at hand isn’t good enough and needs to be either modified or ditched. Thus, science broadly constructed is concerned with the domain of all causal relations in the observable universe. Some may quibble that science is also interested in the causal relations between the observable universe and what remains unobservable, but this doesn’t make my point less relevant. The main message is that if some X can cause Y, and we can detect Y, then both X and Y can be studied scientifically. Thus, science encompasses all causal relations, no matter how subtle or difficult to detect or isolate.
Incidentally, this view of science is what justifies the core attitude of New Atheists: they claim that various religions describe how God causes stuff to happen in our universe, and therefore the causal relation between God and observable facts is by definition within the legitimate remit of science. I have no issue with this view: if something has causal relations with our world, it can and should be studied empirically. I’m remarking this because the implications for philosophy of mind are far fetching: one could be tempted to propose that the mental domain is inherently non-physical. That’s fair enough, but the moment we propose that mental phenomena have some influence on our behaviour, we are still admitting they can be studied scientifically, thus, we are saying that this non-physical domain should still be studied scientifically (in terms of causal relations), making the initial claim that the mental is not physical rather moot: it may not be, but we are still interested in understanding how it interacts with the physical world. If it does interact, it potentially pertains science.
As things stand, it is therefore no surprise that, outside sciences about mind/brain, the idea of epiphenomena is largely absent: when used, all the instances I could find entail a form of weak epiphenomenalism. For example, a biochemist studying how a given hormone is synthesised may note the effects that the hormone has on various organs, and treat these as an epiphenomenon for the purpose of the current study. In other words, in standard everyday science talking about something always assumes that this something can have some effect, however indirect, otherwise talking about it wouldn’t be worth the effort.
More importantly, the idea of epiphenomena as legitimate scientific concepts is so rare that I was unable to find any attempt to reject it outside the philosophy of mind field. It seems that Epiphenomenalism is a concept that is used only in one particular context, and implicitly avoided in the vast majority of scientific disciplines. In my quest, I was hoping to find some ready-made argument in support of my thesis, unfortunately (albeit this indirectly supports my claim that science and Epiphenomenalism don’t normally mix), the closest I could get is Swinburne (2011): the article does concern Epiphenomenalism as employed in philosophy of mind, but it does take a broad view on what justifies our belief in scientific theories. For example, Swinburne claims:
A justified belief in a scientific theory (which is not itself a consequence of any higher-level theory in which the believer has a justified belief) requires a justified belief that the theory makes true predictions.
Unsurprisingly, he then reaches conclusions analogous to mine: namely, that epiphenomena can have no place in a scientific theory, or, more precisely, that “(with [one] very small exception) no one can have a justified belief in epiphenomenalism [of the mind-philosophy kind]“.
This leads me back to my proposition 1. (above): if something has no causal powers (none whatsoever) then, whether it exists or not makes exactly zero difference in the world. Zero, nulla, nada, nothing! I could rest my case here: if something has no influence on the world, it is by definition impossible to detect it. Moreover, it should go without saying that if something has no influence on the world, whether it exists or not is entirely irrelevant, for all possible purposes, both practical and theoretical. Note here that we are talking about absolutes: a pure epiphenomenon is something that causes nothing by definition, therefore it concerns us neither in theory nor practice. In contrast, we could have a hypothesis that implies that particle such and such has no influence on what happens on the human scale, but at high energies it suddenly does acquire causal powers, and therefore it is theoretically detectable. Fine: this has nothing to do with epiphenomena, it may be that particle such and such is currently an entirely theoretical notion (was never detected and we don’t know how to detect it), but still, at least for theoretical reasons, whether it exists or not it does concern somebody. By contrast: a model of particle physics which included something which has by definition no causal powers, wouldn’t make sense, it would mean that taking this something out of the model will let the model behave exactly as before – otherwise this something would have casual powers, according to the model in question. This doesn’t negate the fact that plenty of current hypotheses of theoretical physics imply the existence of things we can’t detect, not even theoretically: in these theories such things still have causal powers, but exert them in realms which we can’t reach. Thus, such theories leave me rather cold, but I can’t and don’t wish to claim that they are nonsensical.
More on the point, I maintain that, For All Imaginable Purposes (FAIP), claiming that something has no causal powers, is equivalent to claiming it doesn’t exist. Why? Because whether such thing exists or not, according to the claim, makes no difference, therefore their existence is irrelevant FAIP. Thus, calling something an epiphenomenon is very different from claiming “this thing exists, but I don’t know what it does” (i.e. it’s causal powers are unknown). Such a claim implies that we already have detected something, or have some reasons to expect that this something is in principle detectable, and because of its detectability, we assume it does have at least some causal powers.
I could go on an on, but I would be running in circles: it doesn’t matter how I approach the subject, I always get to the same conclusion. If something can cause exactly nothing, it can’t be detected, it makes no difference whether it’s there or not (not even to itself), and thus FAIP it doesn’t exist. Epiphenomena are epistemically transparent: we can’t detect them, and hypothesising their existence allows us to explain nothing, as they allow to make exactly zero testable predictions. That’s it, from a scientific point of view, proposing the existence of something which makes no difference is a complete and undeniable waste of time and resources.
It remains to be seen whether the concept has some other use: if there is a categorical difference between science and philosophy, and since so much of philosophy of mind uses the concept, perhaps it is a useful concept in that particular domain? This is the subject of my next post.
Swinburne, R. (2011). Could anyone justifiably believe epiphenomenalism? Journal of Consciousness Studies, 18 (3-4), 196-216.