Conversation with David Pearce about digital sentience and the binding problem

Whether digital sentience is possible would seem to matter greatly for our priorities, and so gaining even slightly more refined views on this matter could be quite valuable. Many people appear to treat the possibility, if not indeed the imminence, of digital sentience as a foregone conclusion. David Pearce, in contrast, is skeptical.

Pearce has written and spoken elaborately about his views on consciousness. My sense, however, is that these expositions do not always manage to clearly convey the core, and actually very simple reasons underlying Pearce’s skepticism of digital sentience. The aim of this conversation is to probe Pearce so as to shed greater — or perhaps most of all simpler — light on why he is skeptical, and thus to hopefully advance the discussions on this issue among altruists working to reduce future suffering.


MV: You are skeptical about the possibility of digital sentience. Could you explain why, in simple terms?

DP: Sure. Perhaps we can start by asking why so many people believe that our machines will become conscious (cf. https://www.hedweb.com/quora/2015.html#definition). Consciousness is widely recognised to be scientifically unexplained. But the computer metaphor of mind seems to offer us clues (cf. https://www.hedweb.com/quora/2015.html#braincomp). As far as I can tell, many if not most believers in digital sentience tend to reason along the following lines. Any well-defined cognitive task that the human mind can perform could also be performed by a programmable digital computer (cf. https://en.wikipedia.org/wiki/Turing_machine). A classical Turing machine is substrate-neutral. By “substrate-neutral”, we mean that whether a Turing machine is physically constituted of silicon or carbon or gallium oxide (etc) makes no functional difference to the execution of the program it runs. It’s commonly believed that the behaviour of a human brain can, in principle, be emulated on a classical Turing machine. Our conscious minds must be identical with states of the brain. If our minds weren’t identical with brain states, then dualism would be true (cf. https://www.hedweb.com/quora/2015.html#dualidealmat). Therefore, the behaviour of our minds can in principle be emulated by a digital computer. Moreover, the state-space of all possible minds is immense, embracing not just the consciousness of traditional and enhanced biological lifeforms, but also artificial digital minds and maybe digital superintelligence. Accordingly, the belief that non-biological information-processing machines can’t support consciousness is arbitrary. It’s unjustified carbon chauvinism.

I think most believers in digital sentience would recognise that the above considerations are not a rigorous argument for the existence of inorganic machine consciousness. The existence of machine consciousness hasn’t been derived from first principles. The “explanatory gap” is still unbridged. Yet what is the alternative?

Well, as a scientific rationalist, I’m an unbeliever. Digital computers and the software they run are not phenomenally-bound subjects of experience (cf. https://www.binding-problem.com/). Ascribing sentience to digital computers or silicon robots is, I believe, a form of anthropomorphic projection — a projection their designers encourage by giving their creations cutesy names (“Watson”, “Sophia”, “Alexa” etc). 

Before explaining my reasons for believing that digital computers are zombies, I will lay out two background assumptions. Naturally, one or both assumptions can be challenged, though I think they are well-motivated.

The first background assumption might seem scarcely relevant to your question. Perpetual direct realism is false (cf. https://www.hedweb.com/quora/2015.html#distort). Inferential realism about the external world is true. The subjective contents of your consciousness aren’t merely a phenomenally thin and subtle serial stream of logico-linguistic thought-episodes playing out behind your forehead, residual after-images when you close your eyes, inner feelings and emotions and so forth. Consciousness is also your entire phenomenal world-simulation — what naïve realists call the publicly accessible external world. Unless you have the neurological syndromes of simultanagnosia (the inability to experience more than one object at once) or akinetopsia (“motion blindness”), you can simultaneously experience a host of dynamic objects — for example, multiple players on a football pitch, or a pride of hungry lions. These perceptual objects populate your virtual world of experience from the sky above to your body-image below. Consciousness is all you directly know. The external environment is an inference, not a given.

Let’s for now postpone discussion of how our skull-bound minds are capable of such an extraordinary feat of real-time virtual world-making. The point is that if you couldn’t experience multiple feature-bound phenomenal objects — i.e. if you were just an aggregate of 86 billion membrane-bound neuronal “pixels” of experience — then you’d be helpless. Compare dreamless sleep. Like your enteric nervous system (the “brain-in-the-gut”), your mind-brain would still be a fabulously complex information-processing system. But you’d risk starving to death or getting eaten. Waking consciousness is immensely adaptive. (cf. https://www.hedweb.com/quora/2015.html#evolutionary). Phenomenal binding is immensely adaptive (cf. https://www.hedweb.com/quora/2015.html#purposecon).

My second assumption is physicalism (cf. https://www.hedweb.com/quora/2015.html#materialism). I assume the unity of science. All the special sciences (chemistry, molecular biology etc) reduce to physics. In principle, the behaviour of organic macromolecules such as self-replicating DNA can be described entirely in the mathematical language of physics without mentioning “life” at all, though such high-level description is convenient. Complications aside, no “element of reality” is missing from the mathematical formalism of our best theory of the world, quantum mechanics, or more strictly from tomorrow’s unification of quantum field theory and general relativity.

One corollary of physicalism is that only “weak” emergence is permissible. “Strong” emergence is forbidden. Just as the behaviour of programs running on your PC supervenes on the behaviour of its machine code, likewise the behaviour of biological organisms can in principle be exhaustively reduced to quantum chemistry and thus ultimately to quantum field theory. The conceptual framework of physicalism is traditionally associated with materialism. According to materialism as broadly defined, the intrinsic nature of the physical — more poetically, the mysterious “fire” in the equations — is non-experiential. Indeed, the assumption that quantum field theory describes fields of insentience is normally treated as too trivially obvious to be worth stating explicitly. However, this assumption of insentience leads to the Hard Problem of consciousness. Non-materialist physicalism (cf. https://www.hedweb.com/quora/2015.html#galileoserror) drops this plausible metaphysical assumption. If the intrinsic nature argument is sound, there is no Hard Problem of consciousness: it’s the intrinsic nature of the physical (cf. https://www.hedweb.com/quora/2015.html#definephysical ). However, both “materialist” physicalists and non-materialist physicalists agree: everything that happens in the world is constrained by the mathematical straitjacket of modern physics. Any supposedly “emergent” phenomenon must be derived, ultimately, from physics. Irreducible “strong” emergence would be akin to magic.

Anyhow, the reason I don’t believe in digital minds is that classical computers are, on the premises outlined above, incapable of phenomenal binding. If we make the standard assumption that their 1 and 0s and logic gates are non-experiential, then digital computers are zombies. Less obviously, digital computers are zombies if we don’t make this standard assumption! Imagine, fancifully, replacing non-experiential 1s and 0s of computer software with discrete “pixels” of experience. Run the program as before. The upshot will still be a zombie, more technically a micro-experiential zombie. What’s more, neither increasing the complexity of the code nor exponentially increasing the speed of its execution could cause discrete “pixels” somehow to blend into each other in virtue of their functional role, let alone create phenomenally-bound perceptual objects or a unitary self experiencing a unified phenomenal world. The same is true of a connectionist system (cf. https://en.wikipedia.org/wiki/Connectionism), supposedly more closely modelled on the brain — however well-connected and well-trained the network, and regardless whether its nodes are experiential or non-experiential. The synchronous firing of distributed feature-processors in a “trained up” connectionist system doesn’t generate a unified perceptual object — again on pain of “strong” emergence. AI programmers and roboticists can use workarounds for the inability of classical computers to bind, but they are just that: workarounds.

Those who believe in digital sentience can protest that we don’t know that phenomenal minds can’t emerge at some level of computational abstraction in digital computers. And they are right! If abstract objects have the causal power to create conscious experience, then digital computer programs might be subjects of experience. But recall we’re here assuming physicalism. If physicalism is true, then even if consciousness is fundamental to the world, we can know that digital computers are — at most — micro-experiential zombies.

Of course, monistic physicalism may be false. “Strong” emergence may be real. But if so, then reality seems fundamentally lawless. The scientific world-picture would be false.

Yet how do biological minds routinely accomplish binding if phenomenal binding is impossible for any classical digital computer (cf. https://en.wikipedia.org/wiki/Universal_Turing_machine). Even if our neurons support rudimentary “pixels” of experience, why aren’t animals like us in the same boat as classical digital computers or classically parallel connectionist systems?

I can give you my tentative answer. Naïvely, it’s the reductio ad absurdum of quantum mind: “Schrödinger’s neurons”: https://www.hedweb.com/quora/2015.html#quantumbrain.

Surprisingly, it’s experimentally falsifiable via interferometry: https://en.wikipedia.org/wiki/Quantum_mind#David_Pearce 

Yet the conjecture I explore may conceivably be of interest only to someone who already feels the force of the binding problem. Plenty of researchers would say it’s a ridiculous solution to a nonexistent problem. I agree it’s crazy; but it’s worth falsifying. Other researchers just lump phenomenal binding together with the Hard Problem (cf. https://www.hedweb.com/quora/2015.html#categorize) as one big insoluble mystery they suppose can be quarantined from the rest of scientific knowledge.

I think their defeatism and optimism alike are premature. 

MV: Thanks, David. A lot to discuss there, obviously.

Perhaps the most crucial point to really appreciate in order to understand your skepticism is that you are a strict monist about reality. That is, “the experiential” is not something over and above “the physical”, but rather identical with it (which, to be clear, does not imply that all physical things have minds, or complex experiences). And so if “the mental” and “the physical” are essentially the same ontological thing, or phenomenon, under two different descriptions, then there must, roughly speaking, also be a match in terms of their topological properties.

As Mike Johnson explained your view: “consciousness is ‘ontologically unitary’, and so only a physical property that implies ontological unity … could physically instantiate consciousness.” (Principia Qualia, p. 73). (Note that “consciousness” here refers to an ordered, composite mind; not phenomenality more generally.)

Conversely, a system that is physically discrete or disconnected — say, a computer composed of billiard balls that bump into each other, or lighthouses that exchange signals across hundreds of kilometers — could not, on your view, support a unitary mind. In terms of the analogy of thinking about consciousness as waves, your view is roughly that we should think of a unitary mind as a large, composite wave of sorts, akin to a song, whereas disconnected “pixels of experience” are like discrete microscopic proto-waves, akin to tiny disjoint blobs of sound. (And elsewhere you quote Seth Lloyd saying something similar about classical versus quantum computations: “A classical computation is like a solo voice — one line of pure tones succeeding each other. A quantum computation is like a symphony — many lines of tones interfering with one another.”)

This is why you say that “computer software with discrete ‘pixels’ of experience will still be a micro-experiential zombie”, and why you say that “even if consciousness is fundamental to the world, we can know that digital computers are at most micro-experiential zombies” — it’s because of this physical discreteness, or “disconnectedness”.

And this is where it seems to me that the computational view of mind is also starkly at odds with common sense, as well as with monism. For it seems highly counterintuitive to claim that billiard balls bumping into each other, or lighthouses separated by hundreds of kilometers that exchange discrete signals, could, even in principle, mediate a unitary mind. I wonder whether most people who hold a computational view of mind are really willing to bite this bullet. (Such views have also been elaborately criticized by Mike Johnson and Scott Aaronson — critiques that I have seen no compelling replies to.)

It also seems non-monistic in that it appears impossible to give a plausible account of where a unitary mind is supposed to be found in this picture (e.g. in a picture with discrete computations occurring serially over long distances), except perhaps as a separate, dualist phenomenon that we somehow map onto a set of physically discrete computations occurring over time, which seems to me inelegant and unparsimonious. Not to mention that it gives rise to an explosion of minds, as we can then see minds in a vast set of computations that are somehow causally connected across time and space, with the same computations being included in many distinct minds. This picture is at odds with a monist view that implies a one-to-one correspondence between concrete physical state and concrete mental state — or rather, which sees these two sides as distinct descriptions of the exact same reality.

The question is then how phenomenal binding could occur. You explore a quantum mind hypothesis involving quantum coherence. So what are your reasons for thinking that quantum coherence is necessary for phenomenal binding? Why would, say, electromagnetic fields in a synchronous state not be enough?

DP: If the phenomenal unity of mind is an effectively classical phenomenon, then I have no idea how to derive the properties of our phenomenally bound minds from decohered, effectively classical neurons — not even in principle, let alone in practice. 

MV: And why is that? What is it that makes deriving the properties of our phenomenally bound minds seem feasible in the case of coherent states, unlike in the case of decohered ones?

DP: Quantum coherent states are individual states — i.e. fundamental physical features of the world — not mere unbound aggregates of classical mind-dust. On this story, decoherence (cf. https://arxiv.org/pdf/1911.06282.pdf) explains phenomenal unbinding.

MV: So it is because only quantum coherent states could constitute the “ontological unity” of a unitary, “bound” mind. Decoherent states, on your view, are not and could not be ontologically unitary in the required sense?

DP: Yes!

Digital computing depends on effectively classical, decohered individual bits of information, whether as implemented in Turing’s original tape set-up, a modern digital computer, or indeed if the world’s population of skull-bound minds agree to participate in an experiment to see if a global mind can emerge from a supposed global brain.

One can’t create perceptual objects, let alone unified minds, from classical mind-dust even if strictly the motes of decohered “dust” are only effectively classical, i.e. phase information has leaked away into the environment. If the 1s and 0s of a digital computer are treated as discrete micro-experiential pixels, then when running a program, we don’t need to consider the possibility of coherent superpositions of 1s and 0s/ micro-experiences. If the bits weren’t effectively classical and discrete, then the program wouldn’t execute.

MV: In other words, you are essentially saying that binding/unity between decohered states is ultimately no more tenable than binding/unity between, say, two billard balls separated by a hundred miles? Because they are in a sense similarly ontologically separate?

DP: Yes!

MV: So to summarize, your argument is roughly the following: 

  1. observed phenomenal binding, or a unitary mind, combined with 
  2. an empirically well-motivated monistic physicalism, means that
  3. we must look for a unitary physical state as the “mediator”, or rather the physical description, of mind [since the ontological identity from (2) implies that the phenomenal unity from (1) must be paralleled in our physical description], and it seems that
  4. only quantum coherent states could truly fit the bill of such ontological unity in physical terms.

DP: 1 to 4, yes!

MV: Cool. And in step 4 in particular, to spell that out more clearly, the reasoning is roughly that classical states are effectively (spatiotemporally) serial, discrete, disconnected, etc. Quantum coherent states, in contrast, are a connected, unitary, individual whole.

Classical bits in a sense belong to disjoint “ontological sets”, whereas qubits belong to the same “ontological set” (as I’ve tried to illustrate somewhat clumsily below, and in line with Seth Lloyd’s quote above).

Is that a fair way to put it?

DP: Yes!

I sometimes say who will play Mendel to Zurek’s Darwin is unknown. If experience discloses the intrinsic nature of the physical, i.e. if non-materialist physicalism is true, then we must necessarily consider the nature of experience at what are intuitively absurdly short timescales in the CNS. At sufficiently fine-grained temporal resolutions, we can’t just assume the existence of decohered macromolecules, neurotransmitters, receptors, membrane-bound neurons etc. — they are weakly emergent, dynamically stable patterns of “cat states”. These high-level patterns must be derived from quantum bedrock — which of course I haven’t done. All I’ve done is make a “philosophical” conjecture that (1) quantum coherence mediates the phenomenal unity of our minds; and (2) quantum Darwinism (cf. https://www.sciencemag.org/news/2019/09/twist-survival-fittest-could-explain-how-reality-emerges-quantum-haze) offers a ludicrously powerful selection-mechanism for sculpting what would otherwise be mere phenomenally-bound “noise”.

MV: Thanks for that clarification.

I guess it’s also worth stressing that you do not claim this to be any more than a hypothesis, while you at the same time admit that you have a hard time seeing how alternative accounts could explain phenomenal binding.

Moreover, it’s worth stressing that the conjecture resulting from your line of reasoning above is in fact, as you noted, a falsifiable one — a rare distinction for a theory of consciousness.

A more general point to note is that skepticism about digital sentience need not be predicated on the conjecture you presented above, as there are other theories of mind — not necessarily involving quantum coherence — that also imply that digital computers are unable to mediate a conscious mind (including some of the theories hinted at above, and perhaps other, more recent theories). For example, one may accept steps 1-3 in the argument above, and then be more agnostic in step 4, with openness to the possibility that binding could be achieved in other ways, yet while still considering contemporary digital computers unlikely to be able to mediate a unitary mind (e.g. because of the fundamental architectural differences between such computers and biological brains).

Okay, having said all that, let’s now move on to a slightly different issue. Beyond digital sentience in particular, you have also expressed skepticism regarding artificial sentience more generally (i.e. non-digital artificial sentience). Can you explain the reasons for this skepticism?

DP: Well, aeons of posthuman biological minds probably lie ahead. They’ll be artificial — genetically rewritten, AI-augmented, most likely superhumanly blissful, but otherwise inconceivably alien to Darwinian primitives. My scepticism is about the supposed emergence of minds in classical information processors — whether programmable digital computers, classically parallel connectionist systems or anything else.

What about inorganic quantum minds? Well, I say a bit more e.g. here: https://www.hedweb.com/quora/2015.html#nonbiological

A pleasure-pain axis has been so central to our experience that sentience in everything from worms to humans is sometimes (mis)defined in terms of the capacity to feel pleasure and pain. But essentially, I see no reason to believe that such (hypothetical) phenomenally bound consciousness in future inorganic quantum computers will support a pleasure-pain axis any more than, say, the taste of garlic.

In view of our profound ignorance of physical reality, however, I’m cautious: this is just my best guess!

MV: Interesting. You note that you see no reason to believe that such systems would have a pleasure-pain axis. But what about the argument that pain has proven exceptionally adaptive over the course of biological evolution, and might thus plausibly prove adaptive in future forms of evolution as well (assuming things won’t necessarily be run according to civilized values)? 

DP: Currently, I can’t see any reason to suppose hedonic tone (or the taste of garlic) could be instantiated in inorganic quantum computers. If (a big “if”) the quantum-theoretic version of non-materialist physicalism is true, then subjectively it’s like something to be an inorganic quantum computer, just as it’s like something subjectively to be superfluid helium — a nonbiological macro-quale. But out of the zillions of state-spaces of experience, why expect the state-space of phenomenally-bound experience that inorganic quantum computers hypothetically support will include hedonic tone? My guess is that futuristic quantum computers will instantiate qualia for which humans have no name nor conception and with no counterpart in biological minds.

All this is very speculative! It’s an intuition, not a rigorous argument.

MV: Fair enough. What then is your view of hypothetical future computers built from biological neurons?

DP: Artificial organic neuronal networks are perfectly feasible. Unlike silicon-based “neural networks” — a misnomer in my view — certain kinds of artificial organic neuronal networks could indeed suffer. Consider the reckless development of “mini-brains”.

MV: Yeah, it should be uncontroversial that such developments entail serious risks.

Okay, David. What you have said here certainly provides much food for thought. Thanks a lot for patiently exploring these issues with me, and not least for all your work and your dedication to reducing the suffering of all sentient beings.

DP: Thank you, Magnus. You’re very kind. May I just add a recommendation? Anyone who hasn’t yet done so should read your superb Suffering-Focused Ethics (2020).

Free Will: Emphasizing Possibilities

I suspect the crux of discussions and worries about (the absence of) “free will” is the issue of possibilities. I also think it is a key source of confusion. Different people are talking about possibilities in different senses without being clear about it, which leads them to talk past each other, and perhaps even to confuse and dispirit laypeople by making them feel they have no possibilities in any sense whatsoever.

Different Emphases

Thinkers who take different positions on free will tend to emphasize different things. One camp tends to say “we don’t have free will, since all our actions are caused by prior causes that are ultimately beyond our own control, and in this there are no ‘alternative possibilities'”.

Another camp, so-called compatibilists, will tend to agree with the latter point about prior causes, but they choose to emphasize possibilities: “complex agents can act within a range of possibilities in a way crude objects like rocks cannot, and such agents truly do weigh and choose between these options”.

In essence, what I think the latter camp is emphasizing is the fact that we have ex-ante possibilities: a range of possibilities we can choose from in expectation. (For example, in a game of chess, your ex-ante possibilities are comprised by the set of moves allowed by the rules of the game.) And since this latter camp defines free will roughly as the ability to make choices among such ex-ante possibilities, they conclude that we indeed do have free will.

I doubt any philosopher arguing against the existence of free will would deny the claim that we have ex-ante possibilities. After all, we all conceive of various possibilities in our minds that we weigh and choose between, and we indeed cannot talk meaningfully about ethics, or choices in general, without such a framework of ex-ante possibilities. (Whether possibilities exist in any other sense than ex ante, and whether this is ethically relevant, are separate questions.)

Given the apparent agreement on these two core points — 1) our actions are caused by prior causes, and 2) we have ex-ante possibilities — the difference between the two camps mostly seems to lie in how they define free will and whether they prefer to emphasize 1) or 2).

The “Right” Definition of Free Will

People in these two camps will often insist that their definition of free will is the one that matches what most people mean by free will. I think both camps are right and wrong about this. I think it is misguided to think that most people have anything close to a clear definition of free will in their minds, as opposed to having a jumbled network of associations that relate to a wide range of notions, including notions of independence from prior causes and notions of ex-ante possibilities.

Experimental philosophy indeed also hints at a much more nuanced picture of people’s intuitions and conceptions of “free will”, and reveals them to be quite unclear and conflicting, as one would expect.

Emphasizing Both

I believe the two distinct emphases outlined above are both important yet insufficient on their ownThe emphasis on prior causes is important for understanding the nature of our choices and actions. In particular, it helps us understand that our choices do not comprise a break with physical mechanism, but that they are indeed the product of complex such mechanisms (which include the mechanisms of our knowledge and intentions, as well as the mechanism of weighing various ex-ante possibilities).

In turn, this emphasis may help free us from certain bad ideas about human choices, such as naive ideas about how anyone can always pull themselves up by their bootstraps. It may also help us construct better incentives and institutions based on an actual understanding of the mechanism of our choices rather than supernatural ideas about them. Lastly, it may help us become more understanding toward others, such as by reminding us that we cannot reasonably expect people to act on knowledge they do not possess.

Similarly, emphasizing our ex-ante possibilities is important for our ability to make good decisions. Mistakingly believing that one has only one possibility, ex ante, rather than thinking through all possibilities will likely lead to highly sub-optimal outcomes, whether it be in a game of chess or a major life decision. Aiming to choose the ex-ante possibility that seems best in expectation is crucial for us to make good choices. Indeed, this is what good decision-making is all about.

More than that, an emphasis on ex-ante possibilities can also help instill in us the healthy and realistic versions of bootstrap-pulling attitudes, namely that hard work and dedication indeed are worthwhile and truly can lead us in better directions.

Both Emphases Have Pitfalls (in Isolation)

Our minds intuitively draw inferences and associations based on the things we hear. When it comes to “free will”, I suspect most of us have quite leaky conceptual networks, in that the distinct clusters of sentiments we intuitively tie to the term “free will” readily cross-pollute each other — a form of sentiment synesthesia.

So when someone says “we don’t have free will, everything is caused by prior causes”, many people may naturally interpret this as implying “we don’t have ex-ante possibilities, and so we cannot meaningfully think in terms of alternative possibilities”, even though this does not follow. This may in turn lead to bad decisions and feelings of disempowerment. It may also lead people to think that it makes no sense to punish people, or that we cannot meaningfully say things like “you really should have made a better choice”. Yet these things do make sense. They serve to create incentives by making a promise for the future — “people who act like this will pay a price” — which in turn nudges people toward some of their ex-ante possibilities over others.

More than that, a naive emphasis on the causal origins of our actions may also lead people to think that certain feelings — such as pride, regret, and hatred — are always unreasonable and should never be entertained. Yet this does not follow either. Indeed, these feelings likely have great utility in some circumstances, even if such circumstances are rare.

A similar source of confusion is to say that our causal nature implies that everything is just a matter of luck. Although this is true in some ultimate sense, in another sense — the everyday sense that distinguishes between things won through hard effort versus dumb luck — everything is obviously not just a matter of luck. And I suspect most people’s intuitive associations can also be leaky between these very different notions of “luck”. Consequently, unreserved claims about everything being a matter of luck also risk having unfortunate effects, such as leading us to underemphasize the importance of effort.

Such pitfalls also exist relative to the claim “you could not have done otherwise”. For what we often mean by this claim, when we talk about specific events in everyday conversations, is that “this event would have happened even if you had done things differently” (that is: the environment constrained you, and your efforts were immaterial). This is very different from saying, for example, “you could not have done otherwise because your deepest values compelled you” (meaning: the environment may well have allowed alternative possibilities, but your values did not). The latter is often true of our actions, yet it is in many ways the very opposite of what we usually mean by “you could not have done otherwise”.

Hence, confusion is likely to emerge if someone simply declares “you could not have done otherwise” about all actions without qualification. And such confusion may well persist even in the face of explicit qualifications, since confusions deep down at the intuitive level may not be readily undone by just a few cerebral remarks.

Conversely, there are also pitfalls of sentiment leakiness in the opposite direction. When someone says “ex-ante possibilities are real, and they play a crucial role in our decision-making”, people may naturally interpret this as implying “our actions are not caused by prior causes, and this is crucial for our decision-making”. And this may in turn lead to the above-mentioned mistakes that the prior-causes emphasis can help us avoid: misunderstanding our mechanistic nature and failing to act on such an understanding, as well as entertaining unreasonable ideas about how we can expect people to act.

 

This is why one has to be careful in one’s communication about “free will”, and to clearly flag these non sequiturs. “We are caused by prior causes” does not mean “we have no ex-ante possibilities”, and conversely, “we have ex-ante possibilities” does not imply “we are not caused by prior causes”.

 


Acknowledgments: Thanks to Mikkel Vinding for comments.

Physics Is Also Qualia

In this post, I seek to clarify what I consider to be some common confusions about consciousness and “physics” stemming from a failure to distinguish clearly between ontological and epistemological senses of “physics”.

Clarifying Terms

Two senses of the word “physics” are worth distinguishing. There is physics in an ontological sense: roughly speaking, the spatio-temporal(-seeming) world that in many ways conforms well to our best physical theories. And then there is physics in an epistemological sense: a certain class of models we have of this world, the science of physics.

“Physics” in this latter, epistemological sense can be further divided into 1) the physical models we have in our minds, versus 2) the models we have external to our minds, such as in our physics textbooks and computer simulations. Yet it is worth noting that, to the extent we ourselves have any knowledge of the models in our books and simulations, we only have this knowledge by representing it in our minds. Thus, ultimately, all the knowledge of physical models we have, as subjects, is knowledge of the first kind: as appearances in our minds.*

In light of these very different senses of the term “physics”, it is clear that the claim that “physics is also qualia” can be understood in two very different ways: 1) in the sense that the physical world, in the ontological sense, is qualia, or “phenomenal”, and 2) that our models of physics are qualia, i.e. that our models of physics are certain patterns of consciousness. The first of these two claims is surely the most controversial one, and I shall not defend it here; I explore it here and here.

Instead, I shall here focus on the latter claim. My aim is not really to defend it, as I already briefly did that above: all the knowledge of physics we have, as subjects, ultimately appears as experiential patterns in our minds. (Although talk of the phenomenology of, say, operations in Hilbert spaces admittedly is rare.) I take this to be obvious, and hit an impasse with anyone who disagrees. My aim here is rather to clarify some confusions that arise due to a lack of clarity about this, and due to conflations of the two senses of “physics” described above.

The Problem of Reduction: Epistemological or Ontological?

I find it worth quoting the following excerpt from a Big Think interview with Sam Harris. Not because there is anything atypical about what Harris says, but rather because I think he here clearly illustrates the prevailing lack of clarity about the distinction between epistemology and ontology in relation to “the physical”.

If there’s an experiential internal qualitative dimension to any physical system then that is consciousness. And we can’t reduce the experiential side to talk of information processing and neurotransmitters and states of the brain […]. Someone like Francis Crick said famously you’re nothing but a pack of neurons. And that misses the fact that half of the reality we’re talking about is the qualitative experiential side. So when you’re trying to study human consciousness, for instance, by looking at states of the brain, all you can do is correlate experiential changes with changes in brain states. But no matter how tight these correlations become that never gives you license to throw out the first person experiential side. That would be analogous to saying that if you just flipped a coin long enough you would realize it had only one side. And now it’s true you can be committed to talking about just one side. You can say that heads being up is just a case of tails being down. But that doesn’t actually reduce one side of reality to the other.

Especially worth resting on here is the statement “half of the reality we’re talking about is the qualitative experiential side.” Yet is this “half of reality” an “ontological half” or an “epistemological half”? That is, is there a half of reality out there that is part phenomenal, and part “non-phenomenal” — perhaps “inertly physical”? Or are we rather talking about two different phenomenal descriptions of the same thing, respectively 1) physico-mathematical models of the mind-brain (and these models, again, are also qualia, i.e. patterns of consciousness), and 2) all other phenomenal descriptions, i.e. those drawing on the countless other experiential modalities we can currently conceive of — emotions, sounds, colors, etc. — as well as those we can’t? I suggest we are really talking about two different descriptions of the same thing.

A similar question can be raised in relation to Harris’ claim that we cannot “reduce one side of reality to the other.” Is the reduction in question, or rather failure of reduction, an ontological or an epistemological one? If it is ontological, then it is unclear what this means. Is it that one side of reality cannot “be” the other? This does not appear to be Harris’ view, even if he does tacitly buy into ontologically distinct sides (as opposed to descriptions) of reality in the first place.

Yet if the failure of reduction is epistemological, then there is in fact little unusual about it, as failures of epistemological reduction, or reductions from one model to another, are found everywhere in science. In the abstract sciences, for example, one axiomatic system does not necessarily reduce to another; indeed, we can readily create different axiomatic systems that not only fail to reduce to each other yet which actively contradict each other. And hence we cannot derive all of mathematics, broadly construed, from a single axiomatic system.

Similarly, in the empirical sciences, economics does not “reduce to” quantum physics. One may object that economics does reduce to quantum physics in principle, yet it should then be noted that 1) the term “in principle” does an enormous amount of work here, arguably about as much as it would have to do in the claim that “quantum physics can explain consciousness in principle” — after all, physics and economics invoke very different models and experiential modalities (economic theories are often qualitative in nature, and some prominent economists have even argued they are primarily so). And 2) a serious case can be made against the claim that even all the basic laws found in chemistry, the closest neighbor of physics, can be derived from fundamental physical theories, even in principle (see e.g. Berofsky, 2012, chap. 8). This case does not rest on there being something mysterious going on between our transition from theories of physics to theories of chemistry, nor that new fundamental forces are implicated, but merely that our models in these respective fields contain elements not reducible, even in principle, to our models in other areas.

Thus, at the level of our minds, we can clearly construct many different mental models which we cannot reduce to each other, even in principle. Yet this merely says something about our models and epistemology. It hardly comprises a deep metaphysical mystery.

Denying the Reality of Consciousness

The fact that the world conforms, at least roughly, to description in “physical” terms seems to have led some people to deny that consciousness in general exists. Yet this, I submit, is a fallacy: the fact that we can model the world in one set of terms which describe certain of its properties does not imply that we cannot describe it in another set of terms that describe other properties truly there as well, even if we cannot derive one from the other.

By analogy, consider again physics and economics: we can take the exact same object of study — say, a human society — and describe aspects of it in physical terms (with models of thermodynamics, classical mechanics, electrodynamics, etc.), yet we cannot from any such description or set of descriptions meaningfully derive a description of the economics of this society. It would clearly be a fallacy to suggest that this implies facts of economics cannot exist.

Again, I think the confusion derives from conflating epistemology with ontology: “physics”, in the epistemological sense of “descriptions of the world in physico-mathematical terms”, appears to encompass “everything out there”, and hence, the reasoning goes, nothing else can exist out there. Of course, in one sense, this is true: if a description in physico-mathematical terms exhaustively describes everything out there, then there is indeed nothing more to be said about it — in physico-mathematical terms. Yet this says nothing about the properties of what is out there in other terms, as illustrated by the economics example above. (Another reason some people seem to deny the reality of consciousness, distinct from conflation of the epistemological and the ontological, is “denial due to fuzziness”, which I have addressed here.)

This relates, I think, to the fundamental Kantian insight on epistemology: we never experience the world “out there” directly, only our own models of it. And the fact that our physical model of the world — including, say, a physical model of the mind-brain of one’s best friend — does not entail other phenomenal modalities, such as emotions, by no means implies that the real, ontological object out there which our physical model reflects, such as our friend’s actual mind-brain, does not instantiate these things. That would be to confuse the map with the territory. (Our emotional model of our best friend does, of course, entail emotions, and it would be just as much of a fallacy to say that, since such emotional models say nothing about brains in physical terms, descriptions of the latter kind have no validity.)

Denials of this sort can have serious ethical consequences, not least since the most relevant aspects of consciousness, including suffering, fall outside descriptions of the world in purely physical terms. Thus, if we insist that only such physico-mathematical descriptions truly describe the world, we seem forced to conclude that suffering, along with everything else that plausibly has moral significance, does not truly exist. Which, in turn, can keep us from working toward a sophisticated understanding of these things, and from creating a better world accordingly.

 


* And for this reason, the answer to the question “how do you know you are conscious?” will ultimately be the same as the answer to the question “how do you know physics (i.e. physical models) exist?” — we experience these facts directly.

Thinking of Consciousness as Waves

First written: Dec 14, 2018, Last update: Jan 2, 2019.

 

How can we think about the relationship between the conscious and the physical? In this essay I wish to propose a way of thinking about it that might be fruitful and surprisingly intuitive, namely to think of consciousness as waves.

The idea is quite simple: one kind of conscious experience corresponds to, or rather conforms to description in terms of, one kind of wave. And by combining different kinds of waves, we can obtain an experience with many different properties in one.

It should be noted that I in this post merely refer to waves in an abstract sense to illustrate a general point. That is, I do not refer to electromagnetic waves in particular (as some theories of consciousness do), nor to quantum waves (as other theories do), nor to any other particular kind of wave (such as Selen Atasoy’s so-called connectome-specific harmonic waves*). The point here is not what kind of wave, or indeed which physical state in general, that mediates different states of consciousness. The point is merely to devise a metaphor that can render intuitive the seemingly unintuitive, namely: how can we get something complex and multifaceted from something very simple without having anything seemingly spooky or strange, such as strong emergence, in between? In particular, how can we say that brains mediate conscious experience without saying that, say, electrons mediate conscious experience? I believe thinking about consciousness in terms of waves can help dissolve this confusion. 

The magic of waves is that we can produce (or to an arbitrary level of precision approximate) any kind of complex, multifaceted wave by adding simple sine waves together.

 

Image result for waves sine
Sine waves with different frequencies.

 

In this way, it is possible, for instance, to decompose any recorded song — itself a complex, multifaceted wave — into simple, tedious-sounding sine waves. Each resulting sine wave can be said to comprise an aspect of the song, yet not in any recognizable way. The whole song is in fact a sum of such waves, not in a strange way that implies strong emergence, but merely in a complicated, composite way.

Another way to think about waves that can help us think more clearly about emergent complexity is to think of a wave that is very small in both amplitude and duration. If this were a sound wave, it would be an extremely short-lived, extremely low-volume sound. On a visual representation of an entire song file, this sound would look more akin to a dot than a wave.

 

Image result for a point math
A dot.

 

And such simple sound waves can also be put together so as to create a song (for instance, one can take the sine waves obtained by decomposing a song and then chop them into smaller bits and decrease their amplitude). It will just, to make a song, take a very great number of such small waves superimposed (if the song is to be loud enough to hear) and in succession (if the song is to last for more than a split-second).

 

The deeper point here is that waves are waves, no matter how small or simple, large or complex. Yet not all waves comprise what we would recognize as music. Similarly, even if all physical states are phenomenal in the broadest sense, this does not imply that they are conscious in the sense of being an ordered, multifaceted whole. Unfortunately, we do not as yet have good, analogous terms for “sound” and “music” in the phenomenal realm — perhaps we could use “phenomenality” and “consciousness”, respectively?

The problem is indeed that we are limited by language, in that the word “conscious” usually only connotes an ordered, composite mind rather than the property of phenomenality in the most general sense. Consequently, if we think all that exists is either music or non-sound, metaphorically speaking, we are bound to be confused. But if we instead expand our vocabulary, and thereby expand our allowed ways of thinking, our confusion can, I think, be readily dissolved. If we think of the phenomenality of the simplest physical systems as being nothing like consciousness in the usual sense of a composite mind but rather as a state of hyper-crude phenomenality — i.e. “phenomenal noise” that is nothing like a song but more akin to a low, short-lived sound, and yet unimaginably more crude still — then the problem of consciousness, as commonly (mis)conceived, seems to become a lot less confusing.**

Avoiding Confusion Due to Fuzziness

A more specific point of confusion the wave metaphor can help us dissolve is the notion that consciousness is so fuzzy a category that it in fact does not really exist, just like tables and chairs do not really exist. As I have argued elsewhere, I think this is a non sequitur. The fact that the categories of tables and chairs are themselves fuzzy does not imply that the physical properties of the objects to which we refer with these labels are inexact, let alone non-existent. The objects have the physical properties they have regardless of how we label them. Or, to continue the analogy to waves above, and songs in particular: although there is ambiguity about what counts as a song, this does not imply that we cannot speak in precise, factual terms about the properties of a given song — for instance, whether a given song contains a 440 Hz tone.

Similarly, the fact that consciousness, as in “an ordered, composite mind”, is a fuzzy category (after all, what counts as ordered? Do psychotic states? Fleeting dreams?) does not imply that any given phenomenal state we refer to with this term does not have exact and clearly identifiable phenomenal properties — e.g. an experience of the color red or the sensation of fear; properties that exist regardless of how outside observers choose to label them.

And although our labels for categorizing particular phenomenal states themselves tend to be fuzzy to some extent — e.g. which part of the spectrum below counts as red? — this does not imply that we cannot distinguish between different states, nor that we cannot draw any clear boundaries. For instance, we can clearly distinguish between the blue and the red zones respectively on the illustration below despite its gradation.

 

Image result for range of color
A linear representation of the visible light spectrum with wavelengths in nanometers.

 

Just as we can point toward a confined range of wavelengths which induce an experience of (some kind of) red in most people upon hitting their retinas, we can also, in principle, point to a range of physical states that mediate specific phenomenal states. This includes the phenomenal states we call suffering, with the fuzziness of what counts as suffering contained within and near the bounds of this range, while the physical states outside this range, especially those far away, do not mediate suffering, cf. the non-red range in the illustration above.

Thus, by analogy to how we can have precise descriptions of the properties of a song, even as an exact definition of what counts as a song escapes us, there is no reason why we should not be able to speak in factual and precise terms about the phenomenal aspects of a mind and its physical signatures, including the “red range” of wavelengths that comprise phenomenal suffering, metaphorically speaking. And a sophisticated understanding of this notional range is indeed of paramount importance for the project of reducing suffering.


* Note that these seemingly different kinds of waves and theories of consciousness can be identical, since connectome-specific harmonic waves could turn out to be coherent waves in the electromagnetic quantum field, as would seem suggested by a hypothesis known as quantum brain dynamics (I do not necessarily endorse this particular hypothesis).

** Another useful analogy for thinking more clearly about the seemingly crazy notion that “everything is conscious” — or rather: phenomenal — is to think about the question, Is everything light? For in a highly non-standard sense, everything is indeed “light”, in that electromagnetic waves permeate the universe in the form of cosmic background radiation, although everything is not permeated by light in the usual sense of visible electromagnetic radiation (wavelengths around 400–700 nm). We may thus think of consciousness as analogous to visible light (they can also both be more or less intense and have various nuances), and electromagnetic radiation as analogous to phenomenality — the more general phenomenon that encompasses the specific one.

 

Why the Many-Worlds Interpretation May Not Have Significant Ethical Implications

At first glance, it seems like the many worlds interpretation of quantum mechanics (MWI) might have significant ethical implications. After all, MWI implies that there are many more sentient beings in the world than one would think given a naive classical view, indeed a much greater number of them. And so it seems quite plausible, at least on the face of it, that ethical considerations pertaining to MWI should dominate everything else in expectation, even if we place only a small credence on this interpretation being true. In this post, I shall outline some reasons why this may in fact not be the case, at least with respect to two commonly supposed implications: 1) extreme caution, and 2) exponentially greater value over time. However, questions concerning the ethical implications of our best physical theories and their interpretations remain open and worth exploring.

Would Branching Worlds Imply Extreme Caution?

“I still recall vividly the shock I experienced on first encountering this multiworld concept [MWI]. The idea of 10100 slightly imperfect copies of oneself all constantly splitting into further copies, which ultimately become unrecognizable, is not easy to reconcile with common sense.”

Bryce DeWitt

This is a common way to introduce the implications of MWI, and it seems plausible that this radically different conception of reality, if true, should lead us to change our actions in significant ways. In particular, it may seem intuitive that it should lead us to act more cautiously, as David Pearce argues:

So one should always act “unnaturally” responsibly, driving one’s car not just slowly and cautiously, for instance, but ultracautiously. This is because one should aim to minimise the number of branches in which one injures anyone, even if leaving a trail of mayhem is, strictly speaking, unavoidable. If a motorist doesn’t leave a (low-density) trail of mayhem, then quantum mechanics is false. This systematic re-evaluation of ethically acceptable risk needs to be adopted world-wide.

Yet, while intuitive, I would argue that this actually does not follow. For although it may be true that we should generally act much more cautiously than we do, this conclusion is not influenced by MWI, for various reasons.

First, if one is trying to reduce suffering, one should not “aim to minimise the number of branches in which one injures anyone”, but rather seek to reduce as much suffering as possible (in expectation) in the world. At an intuitive level, these may seem equivalent, yet they are not. The former is in fact impossible, as we are bound to injure others, even assuming the existence of just one world, whereas the latter — reducing the greatest amount of suffering possible throughout all branches — is possible by definition.

In particular, this argument for being highly cautious ignores the fact that such caution also carries risks — e.g. extreme caution might increase the probability that we will bring about more suffering by omission, by rendering our efforts to reduce suffering less effective. And these other risks may well be much larger, and thus result in the realization of a larger amount of suffering in a larger measure of branches. In other words, since it is far from clear that being ultracautious is the best way to reduce suffering in expectation throughout all branches, it is far from clear that we should practice such ultracaution in light of MWI.

Second, and quite relatedly, I would argue that, whether we live in many worlds or one, we should seek to minimize expected suffering regardless. For if we happened to exist in one world, a small probability of a very bad outcome would be equally worth avoiding, in expectation, as it would be if we happened to live in a quantum multiverse. Whether we do just one or an arbitrarily large number of “trials”, we should still pursue the same action: that which reduces the most suffering in expectation. 

Third, any argument of the kind made above concerning how all slightly probable outcomes will be realized can also be made by assuming that the multiverse of inflation exists. Thus, if one already believes that we live in a spatially infinite, or indeed “merely” extremely large universe, then the radical conclusions supposed to follow from MWI would already be implied by that belief alone (as we shall see below, many prominent proponents of MWI actually consider MWI not only equivalent but identical with the multiverse of inflation). And if one does not think a spatially very large universe should change how we act, then why think that a large, in many ways equivalent, quantum universe should? As argued above, it seems that no radical conclusions should follow either way. One world or many, we should still do what seems best in expectation.

Another way to arrive at the same conclusion is by embracing Stuart Armstrong’s Anthropic Decision Theory, according to which we, as altruists aiming to reduce suffering, should act the same way regardless of how many similar copies of us there may be in the world.

Would Branching Worlds Imply More Value Later?

Following Bryce DeWitt’s quote about rapidly splitting copies, one can reasonably wonder whether MWI implies that the net amount of value in the world, and hence the value of our actions’ impact on the world, is increasing exponentially over time. Indeed, if we naively interpret DeWitt’s claim to mean that the number of sentient beings that exists is multiplied by 10100 just about every second, this would imply that the value of the very last second of the existence of sentient life should massively dominate every thing else. If this interpretation of MWI is correct, it would have extremely significant ethical implications. Yet is it? It would seem not. Here is Max Tegmark:

Does the number of universes exponentially increase over time? The surprising answer is no. From the bird perspective, there is of course only one quantum universe. From the frog perspective, what matters is the number of universes that are distinguishable at a given instant—that is, the number of noticeably different Hubble volumes. Imagine moving planets to random new locations, imagine having married someone else, and so on. At the quantum level, there are 10 to the 10118 universes with temperatures below 108 kelvins. That is a vast number, but a finite one.

From the frog perspective, the evolution of the wave function corresponds to a never-ending sliding from one of these 10 to the 10118 states to another. Now you are in universe A, the one in which you are reading this sentence. Now you are in universe B, the one in which you are reading this other sentence. Put differently, universe B has an observer identical to one in universe A, except with an extra instant of memories.

Thus, it seems one should think about MWI in terms of an intertwining rope rather than a branching tree. A good way to gain intuition about it may be to think in terms of the multiverse of inflation instead. Indeed, according to prominent proponents of MWI, the many-worlds of quantum mechanics and the multiverse of inflation are not only closely related notions but indeed the same thing, cf. (Aguirre & Tegmark, 2010Nomura, 2011Bousso & Susskind, 2011). In that case, not only is thinking about copies of ourselves in worlds spatially far away from us a great way to gain intuition about MWI; it is the correct way to think about it.

And when we think about it in these terms, it suddenly all becomes quite straightforward and intuitive, at least relatively speaking. For on the inflationary model, there are copies of us in the universe located far away with whom we share our entire history from the big bang up until now. Yet as time progresses, and more different outcomes become possible, the distance to the copies of us that share our exact history becomes ever greater, at a rapid pace, cf. (Garriga & Vilenkin, 2001). Thus, there is indeed a rapid branching in a very real sense, only, this branching consists in departing from “nearby” copies of us who had been just like us up until this point. No new worlds are really added. The “other worlds” were always there, and then merely went their separate ways.

Hence, given the assumptions made here, the number of sentient beings in our world does not in fact increase exponentially in the way naively supposed above, unless one keeps on aggregating over an exponentially larger fraction of the space that already existed. (There is, however, an exponential increase in the number of new universes created by inflating regions of the universe, assuming inflationary theory is correct. Yet this process does not create an exponentially greater number of sentient beings from our point in space and time, i.e. Earth, 13.8 billion years after the big bang. Rather, these new worlds are all created “from scratch”.) In short, MWI does not appear to imply greater value later.

 

In sum, I have argued that we seem to have good reason to maintain something akin to one-world common sense in most of our decisions (decisions that might influence the creation of new universes would be an exception). This conclusion may, however, be strongly biased given that it comes from a brain that very much wants to preserve common sense.

Explaining Existence

First written: Aug 2018, Last update: Jan 2021.


“Not how the world is, is the mystical, but that it is.”

(“Nicht wie die Welt ist, ist das Mystische, sondern dass sie ist.”)

Ludwig Wittgenstein


Why is there something rather than nothing? How can we explain the fact of existence?

This most fundamental question may be worth pondering for various reasons. Such pondering may help sharpen our thinking about the nature of the world, our place within it, and the scope of our understanding. And it may also just lead us to some significant answers to the question itself.

Is Non-Existence Coherent?

I would argue that the key to (dis)solving this mystery lies in questioning the coherence of the idea that there could be nothing in the first place — the notion that non-existence could exist or be the case. For existing is, after all, exactly what non-existence, by definition, does not. Non-being, by definition, cannot be. Yet, in asking why there is not nothing, we are indeed, somehow, imagining that it could. Essentially, what we are asking is: why is there not “non-isness“? Why could non-being not have been? The answer, I submit, is that the being of non-being is a contradiction in terms.

More specifically, to say that non-being could be is to contradict the principle of non-contradiction, as one then asks for something, or rather “nothing”, to both be and not be at the same time.

As David Pearce put it:

One can apparently state the epistemic possibility of nothing having existed rather than something. But it’s unclear how it could make cognitive sense to talk of the epistemic possibility of nothing-or-other having even been the case. For the notion of something-or-other being the case is about as conceptually primitive as one can get. For just what is the (supposedly non-self-refuting) alternative with which one would be contrasting the generic notion of existence – in the sense of something-or-other being the case – that we have at present? The notion doesn’t seem to make any sense. It’s self-stultifying.

Why Does Anything Exist“, section nine.

Philosopher Bede Rundle made a similar point: “We cannot conceive of there being nothing, but only of nothing being this or that, and that is a use of ‘nothing’ that presupposes there being something.” (p. 113)

Furthermore, even if we were to assume that non-existence could be the case, we would still end up with the conclusion that it actually cannot. For if non-existence were the case, then its being the case would, quite obviously, be a truth, which implies that this truth would at least (also) exist. And yet this truth is not nothing in the strictest sense. In other words, the hypothetical assumption of non-existence obtaining itself implies the existence of (more of) something. And such a supposedly empty state would in fact imply other properties as well, such as the property of being free from contradictions (genuine contradictions could not possibly exist in any possible state of existence, much less one that is purportedly empty). Thus, even the notion of a state with no properties other than its mere being is incoherent.

This may be considered an answer to why there is something rather than nothing: the alternative is simply incoherent, and hence logically impossible. Only “something” could conceivably be the case. And thus, contra Wittgenstein, the real mystery to explain is indeed how the world is, not that it is; to explain which properties the world has, not that it has any. And part of this mystery is to explain why we ever considered the existence of non-existence — as opposed to a very different state of existence — a coherent possibility in the first place, and, by extension, why we ever considered the non-existence of non-existence any more mysterious than the non-existence of square circles.

Necessity and Contingency

Another way to realize that there could not possibly be nothing, even if we were to assume that the notion is coherent, is to think in terms of necessary and contingent facts (following the reasoning of Timothy O’Connor found here). For the suggestion that there might have been nothing essentially amounts to the claim that existence might merely be a contingent, not a necessary fact. Yet the fact that we are here proves that existence was, at the very least, a possibility. In other words, the reality of (at least) the possibility of existence is undeniable. And yet the reality of the possibility of existence is not nothing. It is, in fact, something. Thus, even if we assume that the fact of existence is merely contingent, we still end up with the conclusion that it is in fact necessary. The existence of the mere possibility of existence necessarily implies, indeed amounts to, existence in full, and hence the suggestion that existence may merely be contingent, and that there could instead have been absolutely nothing, is revealed to be impossible and indeed incoherent in this way as well.

Beyond that, one can use a similar contingency-versus-necessity argument to argue for the necessity of physical existence in particular (without assuming that physical existence is coterminous with existence). For the claim that the non-existence of the physical world could have obtained also amounts to claiming that its existence is merely a contingent fact: a possibility that could have not obtained. Yet the fact that the physical world does exist proves that its existence is necessarily (at least) a possibility. Thus, by this reasoning, there must necessarily exist (at least) a potential for the physical world as we know it to emerge. And yet such a potential is not nothing, nor is it non-physical proper, at least not in the widest sense of the term “physical”, which includes not only physical actualities but also physical potentials, provided they exist.

One may object that the notions of contingency and necessity ultimately do not make sense, or that they are just human ideas that we cannot derive deep metaphysical truths from. Yet it should then be noted that the notion of contingency is exactly what a claim such as “physical reality might not have been” itself rests upon. So if these terms and the argument above make no sense or have no bearing on the actual nature of reality, then neither does the problem the argument is trying to address in the first place.

No Purpose or Reason Behind Existence, Only Within

The all-inclusive nature of existence implies that, just as there cannot be a mechanism or principle that lies behind or beyond existence, there could not be a reason or purpose behind it either, since behind and beyond existence lies only that which does not exist. And hence there could not possibly be an ultimate purpose, in this sense at least, behind our being here.

Yet this by no means implies, contrary to what may be naturally supposed, that reasons and purposes, of the most real and significant kinds, do not exist within existence. Indeed, it is obvious that they do. For instance, the ability to pursue purposes and act on reasons has clearly emerged over the course of evolution. Beyond that, it is also clear, at least to me, that some states of the world — especially states of extreme suffering — are truly more disvaluable than others, and hence, I would argue, that we have good reason to act so as to minimize the realization of such disvaluable states, and to work to create a better world. This seems to me our true and highest purpose.

A Brief Note on Eternalism and Impacting the Future

Something I find puzzling is that many people in intellectual circles seem to embrace the so-called eternalist view of time, which holds that the past, present, and future all equally exist already, yet at the same time, in terms of practical ethics, these same people focus exclusively on impacting the future. These two positions do not seem compatible, and it is interesting that no one seems to take note of this, and that no attempt seems to be made at reconciling them, or otherwise examining this issue. 

For why, given an eternalist view of time, should one focus on impacting the future rather than the past? After all, the eternalist view of time amounts precisely to the rejection of the common sense view that the past is fixed while the future is not, which is the common sense view of time that seems to underpin our common sense focus on trying to impact the future rather than the past. So how can one reject the common sense view of time that seems to underlie our common sense practical focus, yet then still maintain this focus? If the past and the future equally exist already, why focus more on trying to impact one rather than the other?

The only attempted reply I have heard to this question so far, which came from Brian Tomasik, is that if, hypothetically, the present were different, then the future would be different, and hence it makes sense to focus on such changes that would render the future different. The problem, however, is that the same argument applies to the past: if, hypothetically, the present were different, then, for the equations of physics to be consistent, the past would also have to be different. Tomasik seemed to agree with this point. So I fail to see how this is an argument for focusing on impacting the future rather than the past given an eternalist view of time.

Possible Responses

There are various ways to respond to this conundrum. One can, for instance, try to argue that there is no conflict between eternalism and focusing only on impacting the future (which seems the prevailing assumption, but I have yet to see it defended). Another path one could take is to argue that we in fact should focus on impacting the past just as much as the future (something I find highly dubious). Alternatively, one could argue that it is just as senseless to try to change the future as it is to change the past (something few would be willing to accept in practice). Lastly, one could take the tension between these two widely esteemed views to imply that there may be something wrong with the eternalist view of time, and at the very least that we should lower our credence in eternalism, given its ostensible incompatibility with other, seemingly reasonable beliefs.

My Preferred Path: Questioning Eternalism

I would be curious to see attempts along any of the four paths mentioned above. I myself happen to lean toward the last one. I think many people display overconfidence with respect to the truth of eternalism. The fact that the equations of the theory of relativity, as they stand, do not demand an ontologically existing “now does not imply that no such thing exists (where this now, it must be noted, is not defined by “clocks all show the same”, as such a now clearly is impossible; yet there is no contradiction whatsoever in the existence of a unique, ontologically real “present” in which initially synchronized clocks show different times). In other words, although the equations of relativity do not demand the existence of such a now, they do not rule it out either. Yet it seems a widely entertained fallacy that they do, and people thus seem to accept that eternalist view as though it were a matter of logical certainty, when it is not. I think this is bad philosophy. And I think it is important to point this out, since false certainties can be dangerous in unexpected ways (for example, if the above-mentioned fallacy led us to falsely conclude that trying to impact the future is senseless).

Beyond that, as I have noted elsewhere, one can also question to what extent it makes sense to say — as eternalists often do, and as the name eternalism itself implies — that all moments exist “always”? After all, doesn’t “always” refer to something occurring over time? The meaning of claims of the sort that “every moment exists always” is, I believe, less obvious than proponents of eternalism appear to think, and seems in need of unpacking.

A General Note on Our Worldview

I think the tension explored here speaks to a more general point about our worldview, namely that we often do not derive the more practical views we hold (such as the view that we can influence the future but not the past), from our fundamental ontological theories of how the world works. Instead, such views are often derived mostly from tacit common sense notions and intuitions (which is not to say that these views should necessarily be rejected, and certainly not on this ground alone). This means that sometimes — quite often, in fact — the views we hold on various subjects, such as the philosophy of time and practical ethics, are scarcely compatible. The project of bringing the various beliefs we hold across these different areas in concert is, I believe, an important and potentially fruitful one, for our theoretical views in themselves, as well as for our practical efforts to act reasonably in the world.

“The Physical” and Consciousness: One World Conforming to Different Descriptions

My aim in this essay is to briefly explain a crucial aspect of David Pearce‘s physicalist idealist worldview. In particular, I seek to explain how a view can be both “idealist” and “physicalist”, yet still be a “property monist” view.

Pearce himself describes his view in the following way:

“Physicalistic idealism” is the non-materialist physicalist claim that reality is fundamentally experiential and that the natural world is exhaustively described by the equations of physics and their solutions […]

So Pearce’s view is a monist, idealist view: reality is fundamentally experiential. And this reality also conforms to description in physical terms. Pearce is careful, however, to distinguish this view from panpsychism, which Pearce, in contrast to his own idealist view, considers a property dualist view:

“Panpsychism” is the doctrine that the world’s fundamental physical stuff also has primitive experiential properties. Unlike the physicalistic idealism explored here, panpsychism doesn’t claim that the world’s fundamental physical stuff is experiential. Panpsychism is best treated as a form of property-dualism.

How, one may wonder, is Pearce’s view different from panpsychism, and from property dualist views more generally? This is something I myself have struggled a lot to understand, and inquired him about repeatedly. And my understanding is the following: according to Pearce, there is only consciousness, and its dynamics conform to physical description. Property dualist views, in contrast, view the world as having two properties: the stuff of the world has insentient physical properties to which separate, experiential properties are somehow attached.

Pearce’s view makes no such division. Instead, on Pearce’s view, description in physical terms merely constitutes a particular (phenomenal) mode of description that (phenomenal) reality conforms to. So to the extent there is a dualism here, it is epistemological, not ontological.

The Many Properties of Your Right Ear

For an analogy that might help explain this point better, consider your right ear. What properties does it have? Setting aside the question concerning its intrinsic nature, it is clear that you can model it in various ways. One way is to touch it with your fingers, whereby you model it via your faculties of tactile sensation (or in neuroanatomical terms: with neurons in your parietal lobe). You may also represent your ear via auditory sensations, for example by hitting it and noticing what kind of sound it makes (a sensation mediated by the temporal lobe). Another way, perhaps the clearest and most practical way for beings like us, is to model it in terms of visual experience: to look at your right ear in the mirror, or perhaps simply imagine it, and thereby have a visual sensation that represents it (mediated by the occipital lobe).

[For most of us, these different forms of modeling are almost impossible to keep separate, as our touching our ears automatically induces a visual model of them as well, and vice versa: a visual model of an ear will often be accompanied by a sense of what it would be like to touch it. Yet one can in fact come a surprisingly long way toward being able to “unbind” these sensations with a bit of practice. This meditation and this one both provide a good exercise in detaching one’s tactile sense of one’s hands from one’s visual model of them. This one goes even further, as it climaxes with a near-total dissolution of our automatic binding of different modes of experience into an ordered whole.]

Now, we may ask: which of these modes of modeling constitute the modeling we call “physical”? And the answer is arguably all of them, as they all relate to the manifestly external (“physical”) world. This is unlike, say, things that are manifestly internal, such as emotions and thoughts, which we do not tend to consider “physical” in this same way, although all our sensations are, of course, equally internal to our mind-brain.

“The physical” is in many ways a poorly defined folk term, and physics itself is not exempt from this ambiguity. For instance, what phenomenal mode does the field of physics draw upon? Well, it is certainly more than just the phenomenology of equations (to the extent this can be considered a separate mode of experience). It also, in close connection with how most of us think about equations, draws heavily on visuospatial modes of experience (I once carefully went through a physics textbook that covered virtually all of undergraduate level physics with the explicit purpose of checking whether it all conformed to such description, and I found that it did). And we can, of course, also describe your right ear in “physics” terms, such as by measuring and representing its temperature, its spatial coordinates, its topology, etc. This would give us even more models of your right ear.

 

The deeper point here is that the same thing can conform to description in different terms, and the existence of such a multitude of valid descriptions does not imply that the thing described itself has a multitude of intrinsic properties. In fact, none of the modes of modeling an ear mentioned above say anything about the intrinsic properties of the ear; they only relate to its reflection, in the broadest sense.

And this is where some people will object: why believe in any intrinsic properties? Indeed, why believe in anything but the physical, “reflective”, (purportedly) non-phenomenal properties described above?

To me, as well as to David Pearce (and Galen Strawson and many others), this latter claim is self-undermining and senseless, like a person reading from a book who claims that the paper of the book they are reading from does not exist, only the text does. All these modes of modeling mentioned above, including all that we deem knowledge of “the physical” are phenomenal. The science we call “physics” is itself, to the extent it is known by anyone, found in consciousness. It is a particular mode of phenomenal modeling of the world, and thus to deny the existence of the phenomenal is also to deny the existence of our knowledge of “physics”.

Indeed, our knowledge of physics and “the physical” attests to this fact as clearly as it attests to anything: consciousness exists. It is a separate question, then, exactly how the varieties of conscious experience relate to descriptions of the world in physical terms, as well as what the intrinsic nature of the stuff of the world is, to the extent it has any. Yet by all appearances, it seems that minds such as our own conform to physical description in terms of what we recognize as brains, and, as with the example of your right ear, such a physical description can take many forms: a visual representation of a mind-brain, what it is like to touch a mind-brain, the number of neurons it has, its temperature, etc.

These are different, yet valid ways of describing aspects of our mind-brains. Yet like the descriptions of different aspects of an ear mentioned above, these “physical” descriptions, while all perfectly valid, still do not tell us anything about the intrinsic nature of the mind-brain. And according to David Pearce, the intrinsic nature of that which we (validly) describe in physical terms as “your brain” is your conscious mind itself. The apparent multitude of aspects of that which we recognize as “brains” and “ears” are just different modes of conscious modeling of an intrinsically monist, i.e. experiential, reality.

 


The view of consciousness explored here may seem counter-intuitive, yet I have argued elsewhere that using waves as a metaphor can help render it less unintuitive, perhaps even positively intuitive.

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