In Search of Reality – It’s all just Particles

The two topics I discuss in this article, downward causation and panpsychism, both come from Sam Harris’ Waking Up podcast #124 in which he sits down with physicist Sean Carroll to discuss… well, reality. Rather than working through these ideas in any detail, what I will mainly do is respond to Carroll’s criticism of them as “…attempts to wriggle around basing reality in stuff obeying the laws of physics [which] don’t quite hold together”.[1]


Downward Causation

Early on in the podcast, Carroll brings up downward causation, which is the idea that activity at a macroscopic level can somehow feed back and affect behaviour at the microscopic level in a way you wouldn’t understand if you were only studying the microscopic. With this, he is taking aim at the idea that consciousness can affect any of the ‘real’ physical constituents and processes from which it emerges. Now, if you start with the idea that the ‘real’ is the world as described by physics, which, by definition, means elementary particles and the physical laws that govern their behaviour, then Carroll is obviously right. But is this apparently reasonable claim as reasonable as it seems?

First, he claims that the micro determines the macro and this process can’t work in reverse. There are two glaring contradictions here. According to quantum physics itself, macro-scale measurement does, in fact, influence micro-scale behaviour. Wave-particle duality is a classic example of this. If we measure for a particle, we get one; if we measure for a wave, we get that instead! So, verifiable, macro-scale, experimental results not only affect the micro-scale, but actually determine what is at that scale. The second contradiction is that even upward causation between the microscopic and macroscopic doesn’t hold. The quantum world is notoriously weird. We’re talking about a realm where faster-than-light communication is possible, where particles can ‘tunnel’ through space, leaving one location to appear in another without passing through the intervening space, or even literally being in two opposing states at the same time. None of this maps onto anything at the macro level. Indeed, as far as I am aware, this is one of the greatest mysteries in modern physics; i.e. why quantum effects are restricted to the quantum level; i.e. why the micro and the macro are so different.


Second, Carroll is starting from the proposition that the ‘real’ is ultimately the world as described by physics (particles and natural forces). Emergent features, like consciousness (whatever it might be), have no ‘real’ causal effects whatsoever; that is, they can’t affect the behaviour of any of those particles. Now, if one doesn’t deny the existence of consciousness altogether,[2] then the only remaining option is epiphenomenalism; the idea that consciousness is an emergent feature of neural activity but one that is causally impotent; something like a shadow, which appears under certain circumstances but can’t causally interact with anything.

This might not seem like such a big bullet to bite. You can apparently preserve all aspects of mental life; emotions, thoughts, qualia, etc., by saying they emerge naturally from the physical world. Your experience of seeing red just is what it is to have those particular neurons fire in that particular way. Analogously, the wetness of water just is what it is to have hydrogen and oxygen atoms combine in a particular way. But there are some significant problems. First, reducing everything real, including subjective experience, to the interactions of physical clumps of matter renders that very subjectivity impossible to explain. Second, epiphenomenalism completely destroys both morality and meaning.

The first issue overlaps with a point I will make in the next section, ‘panpsychism’, where I look at how consciousness can emerge from non-conscious parts, so I will defer further discussion of this until then. To the second point, any morality worthy of the name must include the possibility of making normative prescriptions; i.e. you must be able to make ‘ought’ claims, like “you ought to maximise happiness” or “you ought not to lie”, etc. But what kind of ‘ought’ claims can you make in a universe where everything just happens according to natural laws governing fundamental particles? Even saying something like, “we ought to maximise the particular kinds of particle interactions that result in the emergence of positive emotions” doesn’t make sense, because the collection of particles you think of as you, can’t do anything other than what they will do (they’re just helpless particles obeying the laws of physics, remember). And don’t forget, none of those emergent mental phenomena, even the ones where you think you ought to do something, are supposed to be able to have any causal effects whatsoever, anyway. Morality doesn’t survive the leap to a true materialist universe.

It’s also difficult to see where you might be able to find anything like meaning or value in such a universe. Granted, the thought, “Wow, this sunset is beautiful” (a value statement) might emerge one evening and it might even be accompanied by a pleasant, peaceful feeling, but if all mental phenomena are just the inexorable interactions of fundamental particles, your judgement is completely stripped of any and all meaning it might have had. It would be like being a character in a video game, one in which, not only your actions but your thoughts and emotions as well, were all being controlled by someone in the ‘real world’. If, as this character, you were capable of realising your imprisonment, would you really still proclaim the thoughts and emotions being put into your head have any significance or meaning as your thoughts and emotions?


The point of all this is not to argue for downward causation, merely to point out the fairly significant problems associated with rejecting it through an appeal to physics. Yes, the idea of downward causation appears nonsensical in a physical universe, but so do subjectivity, morality, and value; not to mention the fact that quantum mechanics itself isn’t even playing by the physical laws of the universe that Carroll relies on to argue against downward causation.

Let me close this section with one final thought that occurred to me in making the epiphenomenalism – shadow analogy. The analogy worked because shadows, not being directly composed of atoms themselves, are unable to physically influence anything; but what if the being the shadow emerges from sees its own shadow? Could it then not decide to do something it may never have considered doing had its shadow never emerged? In other words, couldn’t the emergence of the shadow alter the behaviour of the atoms that make up the being to whom the shadow belongs, precisely in a way you wouldn’t understand if you had only been studying those atoms?



Image result for panpsychism

This discussion leads into another problem that more specifically concerns the emergence of conscious experience from non-conscious particles and laws; namely, how is such a thing possible? How can simply assembling pieces of matter, no matter how ingenious the architecture, ever make it so there is something it is like to be that clump of matter? The analogy with the wetness of water fails here because that is a structural, therefore still purely physical, feature of the way atoms cohere into larger groupings. Conscious experience is something so completely different from clumps of matter, no one would believe it could happen if we weren’t already conscious.

This is already challenging the idea that the ‘real’ is the physical, because if that were true, a complete physical description of a situation would also be a complete description of the situation; i.e. the physical description would tell you everything you could possibly know about it. This can’t be true. Imagine a world of non-conscious robots. They are extremely sophisticated and completely autonomous but no more conscious than your smartphone; i.e. none of them have any conscious experiences whatsoever. If a conscious human were to land on their planet one day and the aliens were to analyse in perfect detail the processes taking place in her brain when she looks at the colour red, all they would be able to determine is which neurons are doing what. There is no way they could ever come to know about the emergent qualia of ‘redness’. It’s just not there in the physical description. This, by the way, is why we have absolutely no idea what it is like to be a bat, or indeed whether it is like anything at all! We can scan bats’ brains all we like but this will never tell us anything about the actual, emergent experience (if there is one) of sending and receiving sonar signals.


There is one theory which seems to be enjoying a bit of a resurgence in popularity these days and might go some of the way towards providing an explanation of how consciousness emerges from matter; panpsychism. This is the idea that all physical matter has mental properties. Carroll finds this wildly implausible, arguing that it’s little more than a last ditch attempt by people who refuse to accept the idea that consciousness can emerge from non-conscious atoms.

Now, this is not a very compelling argument against panpsychism. Of course people refuse to accept the idea of emergence; but they do so not because they think it’s false, but because, despite being trivially true (obviously conscious experience arises somehow from physical neurons in the brain), it explains absolutely nothing, all the while begging the question as to how conscious experience can ever ‘emerge’ from non-conscious particles in the first place. What tends to be forgotten in discussions about ‘emergence’ is that it is a description, not an explanation. It describes what happens, despite the fact that what happens makes absolutely no sense whatsoever. Consciousness doesn’t exist in matter (i.e. the ‘real’), but if you arrange some of those building blocks just so, voila, consciousness! This would be bad enough but then it denigrates other perfectly rational, reasonable ideas[3] as if it were actually making some meaningful claim.

Of course, panpsychism has problems[4] but no one is suggesting otherwise. Panpsychism is an attempt to explain emergence, precisely because emergence doesn’t do any explaining itself. Sure, panpsychism makes a fairly bold claim; all matter is conscious in some way, or consciousness somehow pervades all matter, but this is no more radical than what amounts to the incoherent claim that consciousness somehow ‘emerges’ from an aggregation of non-conscious parts. At any rate, as with downward causation, my point here is not to argue for panpsychism, but to resist the flippant dismissal of it as some half-crazed notion people who have an axe to grind against physics are forced into for want of better options.


Bringing it Home

As I mentioned at the beginning of the article, Carroll sums up ideas like downward causation and panpsychism as “…attempts to wriggle around basing reality in stuff obeying the laws of physics [which] don’t quite hold together”. I think this dismissal of these ideas is quite unfair for two reasons. First, as I have tried to outline above, the reductive materialist position (which is basically what Carroll is representing here) on both of these points has at least as many problems holding together as any other position. Second, this characterisation of proponents of any non-reductive materialism as attempting to “wriggle around basing reality in stuff obeying the laws of physics” makes it sound like they have a hidden agenda and are trying to sneak in some non-physical or mystical influences. While this may be true in some cases, on the whole I think they are merely trying to solve genuine problems that reductive materialism ignores on good days and flat out denies on bad ones.



[1] Carroll, S. M. (Guest). (2018, April 21). Waking Up #124 – In Search of Reality [Audio podcast]. Retrieved from

[2] This is a position called eliminativism which is manifestly incoherent because seeming to have conscious experiences is sufficient to actually be having them. If you doubt this, I refer you to Descartes.

[3] I.e. not religious or new age ‘explanations’ which amount to no more than wishful thinking.

[4] Most notably the combination problem; how can the consciousness of the individual parts produce a unified consciousness of the whole? Also, what does it mean to say a particle is conscious?

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