Epiphenomena haunt me: the actual idea that we can explain any phenomena with the aid of the concept is thoroughly alien to me. In turn, this means that I don’t understand why people do rely on the concept, and consequently suggests that I’m probably missing something important. This post is the second part of a series: in part one I’ve explained the concept in general, and explored my understanding of why it seems absent from standard scientific discourse. I’ve also specified that science does occasionally invoke a weak version of Epiphenomenalism, with which I have no issue. The interim conclusion is that science by definition has no use for strong epiphenomena as they have no effect whatsoever. Therefore, whether they exist or not makes no difference, and since science does value parsimony, one can safely treat epiphenomena as non-existent.
In the following I will explore how the concept enters in the topic of philosophy of mind. I will claim that the concept is normally used in the most unhelpful of ways. It’s worth noting that many people before me have tried to show why Epiphenomenalism is logically impossible (see for example Bailey 2006) but for reasons that I can’t even begin to comprehend, the debate seems destined to continue (e.g. Robinson 2012). As always, my own contribution is an attempt to simplify and/or make the issue at hand intelligible to people (simpletons?) like me: it is also a direct consequence of the fact that arguments a la Robinson look like hopeless sophistry to me. I assume my impression is wrong, and that’s why it’s worth trying to put in writing my own personal approach to the problem. Thus, I will claim (as strongly as I can) that Epiphenomenalism is manifestly incoherent, but that it is also actively harmful: if we want to explain minds, we need to reject the idea in the most uncompromising way. If you think I’m wrong, please do let me know!
To the best of my understanding, epiphenomena enter in the philosophy of mind discourse because we can’t figure out how minds relate to matter. We explain the physical world by means of mechanistic (or at least probabilistic) models, but so far there is no accepted idea of why on earth any kind of mechanism would generate a mind. Moreover, it is generally assumed that one day we’ll be able to mechanistically explain how brains work. It’s worth pausing a little while and make explicit what such and explanation entails: we expect that some day we’ll be able to make predictions about the mechanisms within whole brains, which is a slightly convoluted way of saying that we’ll be able to predict what a brain will do. To some extent, we already do: for example we can predict with decent accuracy how certain outputs of a brain will react to changes in hormonal concentrations and so forth. However, the expectation is that someday our understanding will be improved dramatically, and we’ll be able to mechanistically predict what actual people would do in a given situation by simulating the molecular/neural mechanisms that we suppose would happen in their brains.
From a philosophical point of view, this expectation is deeply problematic because the expected “explanation” doesn’t seem to include minds. It would be something that describes molecules that move about, dynamically generating electric potentials and who knows what else. Thus, at the same time, it seems reasonable to expect that such an explanation will not include anything about the self (if it’s just atoms/molecules moving about, there is no individual to be modelled), let alone the feeling of being that self. From here, many cave in the temptation of epiphenomenalism and propose something like:
The mind, the sense of self, the what-it-is-like to be something or someone, the raw sensory experiences, pain and pleasure, are all epiphenomena (for brevity, I’ll call this the Problematic Bunch – PB). Or at least, some PB members are epiphenomena.
Superficially, this stance seems very solid, because otherwise we must conclude that our expectation of being able to mechanistically explain brains is misguided: if any PB member has causal powers, then it will have to be included in the mechanistic explanation. But we have no clue of why a mere mechanism might somehow generate or acquire a feeling, therefore we can’t even start producing a mechanistic explanation of minds, the self, the what-it-is-likeness and so forth. It seems that the only reasonable hypothesis is that a mechanistic explanation of brains will exclude such things. If that is true, then mind, the sense of self, the what-it-is-like to be something, the raw sensory experiences, pain and pleasure are either epiphenomena or illusions in the “they don’t exist” sense.
Uh oh. According to my previous post, For All Imaginable Purposes (FAIP) we should regard epiphenomena as non-existent (if something has no effect, why should we include it in our models?). Thus, we remain with two options (epiphenomena or illusions), and both lead to the same conclusion: members of the PB, For All Imaginable Purposes, don’t exist.
What did I say?
Hang on a second: we have just reached the conclusion that minds, the sense of self, the what-it-is-like to be something, the raw sensory experiences, pain and pleasure don’t exist. You will excuse me if I take this conclusion to be a clear indication that there must be an error in our reasoning somewhere. Sure enough, all of the above does explain very well why the mind-body problem is really tricky (or if you wish, the question of how mere mechanisms get to feel like something), but the reasoning can’t be right! In other words, either my claim that we can safely ignore (as equivalent to non-existing) everything we consider to be a strong epiphenomenon is wrong, or we have to assume that no PB member is an epiphenomenon.
Let’s see if I can convince you: if something is an epiphenomenon, it has no consequences, therefore, when you say “ouch, that hurts” if pain is an epiphenomenon, it isn’t what caused you to say it. Fine: it’s not the pain that made you yell, it’s the mechanism that causes the pain. But saying this is equivalent to saying that your utterance “pain” refers to the mechanism, because otherwise our neat epiphenomenal way out crumbles: if your utterance refers to “pain” the epiphenomenon, then that pain is not an epiphenomenon for it caused you to refer to it. It all boils down to the general principle: if something is supposed to have no causal powers at all, positing its existence has zero explanatory power. Whether it exists or not makes precisely zero difference to our explanation. Thus, if we want to explain minds, or the sense of self, or the what-it-is-like to be something, or raw sensory experiences, or pain and pleasure, we are implicitly assuming they are not epiphenomenal, not in the strong, uncompromising sense: at the very least, we do want to explain why we think that explaining something that makes no difference is not a waste of time.
Now, this line of reasoning would be useful (according to me!), but unfortunately I seem to be strolling very far from the beaten track. On philosophical matters, the role played by epiphenomenalism seems to be the exact opposite. To me, epiphenomenalism suggests that our reasoning must be wrong, and that therefore it’s likely that mechanistic explanations can and have to include the problematic bunch. To a good portion of the rest of the world, it suggests the opposite, by way of the infamous Zombie thought experiment.
Guess what? Zombies are harmful.
If you’re reading this you are almost certainly aware of the idea of Philosophical Zombie (PZ), however, I will summarise my own understanding of it, in order to help my reader spotting if or where I’m getting it wrong. I will start with acknowledging that PZs come in many different forms and variations, however, in this case, I’m concerned only with PZs that entail epiphenomenalism. In particular, from now on, a PZ will be assumed to comply with the following:
A Philosophical Zombie is an exact replica of an actual human being, down to every conceivable physical and behavioural detail, but lacking any inner feeling (what is usually referred to as Phenomenal Experience – PE, the fact that there is something it is like to be that being).
Since I will maintain that such PE doesn’t exist (FAIP), I will refer to the specific PE that zombies don’t have as PPE (Philosophical PE). The argument goes like this, in Bailey’s words:
1) If theory X were true, conscious states would be type-identical with, or at least logically supervenient on X-ish states. […] From this it would follow that – if we hold constant the relevant background facts – it is logically impossible for X-states to occur in the absence of conscious states.
2) Creatures possessing X-states but lacking consciousness – X-Zombies – are conceivable, and whatever is conceivable is logically possible.
3) Thus it is logically possible for X-states to come apart from conscious states and so theory X is refuted.
In more colloquial terms, we start by assuming we do have a theory X which claims to explain why conscious states necessarily happen (1). The zombist then proposes to consider X-Zombies which follow the mechanisms proposed by X but are in fact not-conscious. If we can consider the possibility of such creatures, then they are logically possible (2). Thus, (1) is refuted because logic alone doesn’t show that conscious states necessarily happen (3).
I see two problems with this formulation, but it still looks like the most compelling of the ones I’m aware of. The first problem is something that Bailey doesn’t even mention:
Simply put, we don’t currently have any theory X, only hopes of producing it. Thus, we don’t know what these X-states are, and if we don’t, we can’t properly asses whether X-Zombies are conceivable. Without the full description of the X-mechanisms, we can’t say whether you can build a picture of X that doesn’t entail consciousness (2). In this context, one may be tempted to say: “No, you’re cheating. Physicalism is the theory that consciousness can be explained in mechanistic terms, and we certainly can imagine mechanisms which lack inner feelings, granting us the validity of step 2“. This is the main reason why PZs are so attractive, but is mistaken: physicalism is currently a hope, it doesn’t specify what mechanisms are necessary to produce PE, so it would be wiser not to assume that, whatever X-mechanisms will be proposed, it will always be possible to conceive the corresponding X-Zombies.
However, the second problem seems stronger to me, and is something that underlines most of Bailey’s critique. PZ arguments, when used to support epiphenomenalism, necessarily conform to my first definition above (exact physical replica), and therefore imply that PPE is an epiphenomenon. From this, the direct, unavoidable consequence is that PPE makes no difference whatsoever. In other words, including or not PPE in our explanatory model with leave the model untouched: ex-hypothesis, PPE causes nothing. Now, if our model is explanatory, it makes some phenomena somewhat predictable, so, in case of PE, if our model does claim to explain it (for example, allows to predict what mechanisms produce PE and what don’t), it follows that the PE it explains is not PPE, because PPE is irrelevant, non detectable and completely transparent to all conceivable explanations.
Consider a Zombie Twin World (ZTW), in which all of us are enacted by our own PZ twin. In this world, because my PZ is an exact replica of myself, it would be writing this same essay. My twin would act as if its overall aim would be to contribute to an explanation of PE, but this PE can’t be of the PPE sort, because PPE is completely absent in the ZTW. One could at this point quibble on the fact that I have an aim, but my twin doesn’t (as meaning belongs to the PB), it just acts “as if”. Therefore I should not ascribe aims onto Zombie twins, and in fact my phrase “contribute to an explanation of PE, but this PE can’t be of the PPE sort” is meaningless because in the ZTW there is no meaning. Fine, but then how can you be sure we are not already inside ZTW? Well, according to some, we can because we know we are conscious and we all experience PE. In other words, we (not the zombies!) produce thoughts such as “seeing this red-rose feels of something”, and these thoughts are what tell us that we have the true PE. Furthermore, according to epiphenomenalists, these thoughts are caused by physical events, but the same physical events happen in exactly the same way in ZTW, so zombies will report having the same thoughts as us. So once again: where is the difference?
Therefore, we must acknowledge that our hypothesis assumes that between our world and a ZTW there is a difference that doesn’t make a difference. Such an assumption seems pointless to me, but even if granted, it means that For All Imaginable Purposes, our world and ZTW differ in exactly nothing. This entails that PPE is an empty set: there is no discernible difference between me and my PZ twin, ex-hypothesis. In other words, I’ve been writing about nothing from the start. For example, we can try imagining what would happen if a mechanistic explanation of consciousness is produced: in our world, we expect that it won’t explain PPE, allowing anti-physicalists to ask for more explanations. In ZTW, ex-hypothesis, the same needs to happen: the Zombie replicas of our anti-physicalists will physically mirror what happens here, so they would complain just the same. From this, it follows that a convincing mechanistic explanation of consciousness needs to explain what is in common between our world and ZTW: to be convincing it has to explain what makes people look for epiphenomena, which would grant explanatory powers (or its zombie-equivalent) in both worlds.
On the other hand, trying to explain PPE (Phenomenal Experience under the assumption that it is an epiphenomenon), would, ex-hypothesis, always fail: there is no way to test the prediction “this mechanism produces PPE” because whether it does or doesn’t can’t cause any difference, so at best, one could claim “this system behaves as if it had PPE”, to which the epiphenomenalist can always answer “Congratulations! You’ve produced a convincing zombie”. Thus, the epiphenomenalist, by convincing most specialists that we need to explain something which (FAIP) doesn’t exist, has placed herself in an unbeatable stronghold. No explanation will ever satisfy the epiphenomenalist criteria. That’s because Epiphenomenalism is internally incoherent (it requires to explain something that is FAIP non-existent).
Apart for the clear waste of effort which results from accepting impossible-to-meet criteria (would normally be denounced in standard scientific discourse), I also wish to claim that the notions of PZs and thus PPE are actively harmful. Passively, they waste our time and brainpower, which would be bad enough, but actively, they make finding some answers positively more difficult. Why is it so? Because, if one wants to create a theory of consciousness which is able to command some consensus, it needs to be convincing to scientists and philosophers in equal measure. This generates an impossible to solve deadlock.
On one hand, to satisfy PZ-friendly philosophers, a theory will need to include epiphenomena, and give them a quite important role. Thus, to a trained scientist, such a theory will immediately look suspicious: why would anyone include elements that make no difference? Theories that try to raise to the epiphenomenalist challenge look thoroughly unscientific to the trained eye, and therefore are (rightly) frowned upon by scientists. This is harmful, because it deepens the divide between brain scientists and mind-philosophers: it would be a useful consequence only if philosophy of mind contained exclusively bad ideas, but this seems a manifestly preposterous assumption to make.
On the other hand, as explained above, such a theory is not even possible, on philosophical grounds: any theory that can be produced will either leave out PPE, or fail to necessarily entail PPE, leaving PZ-friendly philosophers able to declare “told you, it’s impossible!”. But this is nonsense: the moment PE is declared an epiphenomenon is the moment when we should stop and admit that it isn’t logically possible.
Whatever it is that we want to explain, it can’t be an epiphenomenon, because we want to explain it!
Thus, epiphenomenalism in theory of mind is inherently nonsensical, at least to my eyes. If something causes nothing, it doesn’t flipping exist, not for any imaginable purpose. However, a great deal of brainpower has been spent in obscuring the internal inconsistency of the whole idea, letting philosophy of mind to more or less collectively accept PPE as a legitimate explananda, which makes every and all proposed explanations unable to gain any philosophical traction. But it’s worse than that: on the science side, scientists at some level detect the absurdity of the situation, shake their heads, and (more or less collectively) turn their backs to philosophy of mind. This is a catastrophe: philosophy of mind is necessary to brain sciences*, precisely because it is able to look ahead and spot a vast number of conceptual obstacles that science will need to tackle. Ignoring those does no one any intellectual good: sure enough, it allows to propose “scientific”** theories of consciousness that are manifestly unable to explain why minds exist, it even allows to take such theories seriously!
In other words, the idea of epiphenomenalism inherently makes its explananda unexplainable, and by doing so allows to waste time, brainpower, money and resources in virtually any direction. For this reason (I’m out!) the idea should be put aside once and for all.
Notes and Bibliography
*Simply put: you can’t tackle the most interesting questions about human brains without considering philosophical questions. For example, this excellent essay by Kevin Mitchell (a bona fide, no-nonsense neuroscientist – not a wannabe like yours truly), makes it perfectly clear that if we want to link brain mechanisms to the choices we make, it is necessary to adopt one or the other theory of causation. Moreover, one gets inevitably thrown in the deep waters of the free-will debate: does proposing a mechanistic explanation negate the freedom of our choices? There is no way to scientifically explore these topics without encountering one or the other philosophical conundrum. When it comes to cognitive neuroscience, ignoring philosophical debates can be considered useful if and only if we assume that all philosophy of mind is worthless. Considering how many of the brightest people have tried their luck on these waters, I find this assumption absurd and a clear manifestation of hubris and wilful ignorance.
**The scare quotes here stand for: theories which claim to be scientific and justify this claim by proudly ignoring the relevant philosophical debates.
Bailey, A. (2006). Zombies, Epiphenomenalism, and Physicalist Theories of Consciousness Canadian Journal of Philosophy, 36 (4), 481-509 DOI: 10.1353/cjp.2007.0000
Robinson, W. (2012). Phenomenal Realist Physicalism Implies Coherency of Epiphenomenalist Meaning Journal of Consciousness Studies, 19 (3-4), 145-163