Summary of The Weirdness of the World

Just what you wanted! And just in time for National Cherry Popsicle Day! A summary of my 2024 book, The Weirdness of the World, by the author himself. You probably haven't had time to read the whole thing (I don't blame you). So here's a synthesis of what I see as the most central ideas.

(I wrote it for a book symposium forthcoming in Journal of Consciousness Studies with critiques by Edouard Machery, Luke Roelofs, Susan Schneider, and a reply by me [with Jacob Barandes, co-author of one of the chapters that Machery targeted in his critique]. I'll share links to the critiques when they're available, along with the final manuscript of my reply.)

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1. Bizarreness and Dubiety.

On fundamental issues of consciousness and cosmology, something both bizarre and dubious must be true, and we’re in no good position to know which of the various bizarre and dubious possibilities in fact holds. That is the guiding idea of The Weirdness of the World.

Interpretation of quantum mechanics isn’t a main theme, but it nicely illustrates the thought. According to many-worlds interpretations, the world is constantly splitting into myriad near-duplicates. According to some versions of the Copenhagen interpretation, observation by humans somehow causes the collapse of the wave function. Other possibilities include Bohmian mechanics and objective collapse theory. All the possibilities are bizarre: They starkly violate the ordinary common sense of nonspecialists. All are also dubious: We have no compelling epistemic grounds to believe any one over all the others. We see several theoretical options, A, B, C, and D. Each option is bizarre and dubious, and it’s a good guess that any viable new options that we add to the mix will also be bizarre and dubious. Quantum mechanics will never fit neatly into common sense, unless common sense changes radically. And there’s no near-term or even medium-term hope of a decisive theoretical resolution.

Across many fundamental issues, bizarreness and dubiety reign. Common sense fails us. So also does scientific and philosophical theorizing. We are adrift in weirdness, unable to anchor.

2. Mind and Body: Universal Bizarreness.

Consider the general relationship of the mind to the apparently physical world. The live options appear to be (1.) materialism, (2.) substance dualism, (3.) metaphysical idealism, or (4.) one of a grab-bag of compromise or alternative views such as panpsychism, property dualism, or transcendental idealism. Each option is both bizarre and dubious, either on its face or when theoretical choices are made and consequences explored.

The bizarreness of materialism is sometimes underappreciated. Weirdness explores materialist bizarreness in two ways (but not only these two):

The pain trilemma. Horn 1: If pain depends on having a brain of a certain physical type, then alien species built very differently from us can never feel pain, no matter how behaviorally and functionally similar. Horn 2: If pain depends instead on having a certain functional profile of inputs and outputs, then strangely constructed entities (e.g., huge assemblies of beer cans and wire) can feel pain if they have the right functional profile; and, conversely, no one can feel pain if their pain plays an unusual causal role. Horn 3: The standard ways to escape these two simple options appeal to typicality or historical function. This entails denying the local supervenience of pain: Two entities can be molecule-for-molecule identical, writhing and evading equally, emitting exactly the same sounds of protest, while one is in pain and the other is not. One of these three options might be correct, but none comports with common sense. A fourth might be discovered, but it’s a good bet that it will not preserve common sense appreciably better.

Group consciousness. If materialism is true, it ought to be possible to arrange groups of people into configurations that give rise to consciousness at the group level, over and above the consciousness of each individual considered separately. Arguably, the United States, conceived as a concrete entity with people as its parts, is such a group. It possesses the main features characteristic of brains in virtue of which materialists ordinarily think brains give rise to consciousness: massive internal information transfer, sophisticated representation and self-representation, sophisticated action in its environment, complex learning, preservation of its boundaries, a long history of interaction with entities of its type in a natural world, and so on. There are various ways in which materialists can avoid concluding that the United States is literally conscious. For example, they can insist that no conscious entity can have a smaller conscious entity as a part. Or they can insist that consciousness requires a highly specific type of internal processing or self-representation, which is not easily achievable in the United States. But each escape brings other counterintuitive consequences in its train. It doesn’t follow that the United States is conscious. But we can’t comfortably retain all of our common sense assumptions about such matters. Something has to give. One or another bizarre thing must be true.

The bizarreness of substance dualism is also sometimes underappreciated. One way to appreciate the bizarreness of dualism is the scope of mentality quadrilemma. Which organisms have immaterial souls? Horn 1: Only human beings. But then, if the soul is the locus of consciousness, even dogs and apes must be entirely nonconscious. Horn 2: Every organism has an immaterial soul. But then even bacteria and slime molds are conscious. Horn 3: There’s a sharp line in the sand between ensouled and unensouled animals. But phylogeny reveals a smooth gradation of capacities and physiologies, with no plausible place to draw a sharp line. Horn 4: Having a soul is not an all-or-nothing matter. Some animals (frogs? ants?) have kind-of-souls or 60% of a soul. But no dualist has ever made good metaphysical sense of this idea.

I think I need not argue that metaphysical idealism, panpsychism, transcendental idealism, and other well-known alternatives to materialism and substance dualism also have points of sharp conflict with common sense.

In the entire history of philosophy, East and West, no philosopher has ever developed an account of the mind-body relation that fully conforms to common sense. By his own admission, even “common sense” philosopher Thomas Reid couldn’t preserve common sense on this issue. For example, he held that physical objects require the action of immaterial souls to sustain their shapes. Philosopher after philosopher delivers bizarreness, both by the standards of their own culture and by the standards of mainstream early 21st century Anglophone readers. The most plausible explanation of this historical pattern is that commonsense opinions about mind and body form an incoherent set, so that no coherent philosophy is able to adhere to the entire package.

3. Mind and Body: Universal Dubiety.

The dubiousness of every answer to fundamental questions concerning the relation of mind and body follows from two considerations.

First is the lack of a good method to resolve such disputes. There is, for example, no good material-world-ometer by which metaphysical idealism can be refuted. Nor is there an epiphenomenal-substance-ometer that can refute epiphenomenalism. Deniers of causally inert epiphenomenal substances usually claim that the universe is appealingly simpler without them. But simplicity is a complex business. Arguably the simplest cosmology is solipsism: Only one thing exists, your own mind. (In a co-authored chapter of Weirdness, I attempt to refute solipsism experimentally with the help of an interlocutor who convinces me to admit the existence of something in the universe that surpasses me at chess.)

Even if we commit to materialism, no general consciousometer can be built that doesn’t beg the question against rival views. To develop a general theory of animal consciousness, we need to presuppose something about the distribution of consciousness in the animal world. How plausible are conservative views that restrict consciousness only to the more sophisticated mammals and birds? How plausible are liberal views that attribute consciousness to insects, worms, and oysters? A theory of consciousness needs some initial assumptions about approximately how sparse or abundant consciousness is in the animal kingdom, or some assumptions from which sparseness or abundance quickly follows. But those assumptions will rightly be unappealing to people who begin with very different initial assumptions. No decent resolution of this tight epistemic circle is on the horizon, no plausible path by which advocates of sparseness can be rationally compelled to abandon their view in favor of abundance or vice versa.

Second, grand-scale cosmological uncertainty warrants uncertainty about the metaphysics of consciousness. For example, if we are living in a computer simulation, then what we think of as the material world might be simply how the underlying computer presents itself to us. The real grounds of conscious experience might be very different than we suppose. Or if the universe is infinite, its laws might be radically different in other regions (which would help address the “fine tuning” problem of why the cosmological constants seem so well suited for life). Materialism might then be a local contingency rather than a metaphysical truth. If a consciousness-based interpretation of quantum collapse is correct, then consciousness might be among the fundamental properties of the universe rather than something arising from physical matter as we ordinarily understand it. I’m not saying any of these possibilities deserves the bulk of our credence, but if mainstream cosmology is correct, we have seen only a very small, perhaps infinitesimal fraction of reality. We are like fleas on the back of a dog, watching a hair grow, and saying “Ah, so that’s how the universe works!”

4. 1% Skepticism.

A radically skeptical scenario is one in which a huge swath of what you ordinarily take for granted is radically false. If you are now dreaming, or if you are a radically deceived brain in a vat, almost all of your perceptual beliefs are false. If the world was created ten minutes ago, almost all of your beliefs about the past are false. It is not unreasonable, I suggest, to have about a 1% credence that some radically skeptical scenario obtains.

There are no grounds for assigning more than a tiny credence to the possibility that aliens extracted your brain while you were sleeping last night, teleported it to Alpha Centauri, and are now feeding it fake input. However, there are grounds for thinking you might currently be dreaming. Past false awakenings show that people sometimes mistakenly judge themselves to be awake. Some leading scientific theories describe dream experiences as subjectively indistinguishable from waking experiences. It’s not unreasonable to assign perhaps a 20% credence to the possibility that you sometimes have, while asleep, experiences much like the experience you are now having, along with a disposition to falsely judge yourself awake. Once I admit this, I find it hard to sustain absolute 100% confidence that I am now awake, or even 99.9999% confidence. About 0.1% credence, plus or minus an order of magnitude, seems about right.

Similarly, for various reasons I think I’m probably not an Artificial Intelligence inhabiting a short-term computer simulation. I feel highly confident that’s false – 99.9% confident! But again absolute certainty, or even 99.9999% certainty, seems out of reach.

Admitting about a 0.1% to 1% credence that I’m in a skeptical scenario is not behaviorally inert. For example, in a situation of almost exact indifference between a short-term gain and a long-term gain, 1% skepticism ought to tilt the balance in favor of the short-term gain.

5. Kant Meets Cyberpunk.

Transcendental idealism is a historically important metaphysical position, associated with Kant, but now unfortunately neglected among non-historians. I offer a how-possibly argument for transcendental idealism. As I intend the phrase, transcendental idealism conjoins two theses: (1.) Spatial properties depend on our minds. (2.) The fundamental features of things as they are in themselves, independent of us, are unknowable to us.

Here’s how transcendental idealism might possibly be true: We are AIs living inside a computer simulation. But the computer running the simulation isn’t material. Instead, it’s an immaterial soul – the mind of an angel. If we accept Turing’s standard account of digital computation, computation does not require a material substrate, as long as there are the functional equivalents of machine states, symbols, a read-write head, and transition functions. Spatiality might then just be our minds’ way of making sense of the structure of the immaterial soul we inhabit.

That we are sims in a virtual reality instantiated in an immaterial angel is not, I admit, very likely! But once we grasp this possibility, we can see more generally how a version of transcendental idealism might be true – perhaps one closer to Kant’s, in which fundamental reality is even less comprehensible than computation in an immaterial soul.

6. Infinite Puppetry.

If standard physical theory is correct, the universe will eventually cool into heat death. During heat death, occasional chance fluctuations will produce lower entropy states, for example when several particles by chance converge into an organized pattern. There appears to be in principle no limit to the size of these fluctuations, and no future temporal boundary on the universe. Given infinite time, large configurations will eventually fluctuate into existence, including particle-for-particle duplicates, within some error tolerance, of your brain, of your brain and your body, and even of the whole galaxy. This is the well-known Boltzmann brain hypothesis.

In a chapter co-authored with Jacob Barandes, we defend the physical plausibility of this hypothesis and derive some causal consequences. Suppose you raise your hand right now, intending eventually to bring into existence a future duplicate of yourself who thinks “I came into existence because an earlier duplicate of me raised their hand”. This intention will likely be fulfilled. By raising your hand, you set in motion a ripple of causal effects that echo forward into the post-heat-death universe, until eventually it produces an entity of exactly the sort you imagine – one who would not have existed had you not raised your hand in that way at that moment (though duplicates of that entity would have existed elsewhere).

7. Debatable Personhood, the Full Rights Dilemma, and the Design Policy of the Excluded Middle.

We don’t understand the metaphysics of consciousness. Even if we assume materialism, we don’t know the right scientific theory of consciousness. We will likely soon create AI systems that are, according to some plausible theories, as richly conscious as ordinary adult human beings, or even more so, while according to other plausible theories, they are no more conscious than a toaster.

I assume that sufficiently rich conscious cognition is sufficient for personhood – sufficient, that is, to deserve humanlike moral consideration and humanlike rights. I also assume that an entity with as little consciousness as a toaster is far short of deserving humanlike moral consideration and rights. Thus, if we create entities whose consciousness is radically debatable, their rights will be radically debatable too.

How should we treat such debatable persons, if we ever create them?

Here we face an unfortunate dilemma. If we deny debatable persons the rights they might deserve, we risk perpetrating the moral equivalent of slavery and murder against them, perhaps on enormous scale. This possibility has been imagined again and again in science fiction, from Asimov to Star Trek to Westworld. If, to avoid that moral risk, we err on the side of granting humanlike rights to debatable persons, we risk sacrificing real human lives for entities without interests worth the sacrifice. Human rights presumably include citizenship, reproduction, property ownership, and the vote. The consequences could be immense, especially if the AI systems in question have interests different from ours and can reproduce quickly. One compromise might be to grant only limited rights – for example, no right to reproduce, no right to vote, no right to privacy of thought. That might be safer for humans, but it would be seriously oppressive if the entities do in fact deserve full humanlike moral consideration.

The full rights dilemma has only one good solution: Don’t create debatable AI persons. I call this the Design Policy of the Excluded Middle (originally proposed with Mara Garza in 2015). Avoid creating AI entities if it’s unclear whether they would deserve moral consideration similar to that of human beings. Either create entities whose moral standing is known to be far less than ours, and prioritize human welfare; or go all the way to creating entities known to be persons and give them the rights they deserve.

[The consciousness question is the topic of my just-released book AI and Consciousness, and the ethical question is the topic of my book in circulating draft, Humanlike: A Defense of AI Rights.]

8. Weirdness and Wonder.

Imagine a planet on the far side of the galaxy, one we will never interact with, forever blocked from view by the galactic core. What do you hope for this planet? Do you hope that it’s a sterile rock? Or do you hope that it hosts life?

I think you will join me in hoping that it hosts life. Not just microbial life, but even better, plants and animals. Not just plants and animals, but even better, intelligent creatures capable of abstract thought and long-term social cooperation, capable of love and art and science and philosophy. That would be an amazing, wonderful, awesome planet!

Earth, for the same reasons, is an amazing, wonderful, awesome planet. Among the most awesome things about Earth is this: Certain bags of mostly water can contemplate profound and difficult questions about the fundamental nature of things, their position in the cosmos, the grounds of their values, the limits of their own knowledge. A world in which no one ever did this would be sadly impoverished. The ability to reflect seriously on these questions is cause for celebration even if we can’t find our way to the answers.

Earth is a bright spot of value in the cosmos in part because it contains human beings who, driven by curiosity and a non-instrumental desire to address hard questions, attempt some philosophy. Philosophical inquiry makes the entire planet better. Assume for a minute the worst about philosophy: that it has no instrumental value for other ends, that philosophers will never agree on the correct answers to anything, that studying ethics makes us no ethically better (as my own empirical research on the behavior of ethicists tends to suggest), that philosophy often only serves to rationalize our vices, that our philosophical inclinations reveal more about our fixations and pathologies than about the world we seek to understand. Fine and (for the sake of argument) granted! Maybe it really is that bad. And yet, simply to pose a philosophical question is already a magnificent cognitive achievement. Our capacity for philosophical inquiry separates us from all other species. It makes Earth a very different and more interesting planet than it would otherwise be.

By reading this blog post, you have made this region of the cosmos more wondrous. Now go enjoy a cherry popsicle.

New in Draft: Strange Intelligence: Moral Puzzles of Unhumanlike AI

Available here.

Abstract: Future AI persons might both (1.) deserve moral consideration and rights fully equal with natural human persons, and (2.) have lifeways so radically different from ours as to break familiar patterns of moral thinking by violating our ordinary background assumptions. This article presents a series of thought experiments about strange AI persons, centering on a two-pronged worry featuring two types of "monster". "Utility monsters", who derive great personal benefit from harming others, create a well-known challenge for ethical systems that aim to maximize aggregate goods. The less-discussed case of "fission-fusion monsters", who can divide and merge at will, presents a complementary challenge to ethical systems focused on individual rights, since individual rights frameworks require the existence of stable, countable individual persons. AI cases dramatically expand the range of possible lifeways, creating untested problem cases for ethical systems that assume persons of the familiar humanlike sort.

To focus on the issues of interest, I assume the possibility of AI consciousness in this article. My skeptical overview of the issue of AI consciousness is here.

Excerpt (with light modification for independent readability):

3. Fission and Identity.

Backup is only the most modest duplicative possibility. If backup is possible, duplicative fission almost certainly will be possible too. Buy the new robot body before the old one dies and install the "backup" right away. Now Shriya-1 and Shriya-2 exist contemporaneously -- twin sisters, so to speak, who begin even more identical than "identical" human twins. We might imagine a billionaire Shriya creating thousands of duplicates of herself -- maybe millions or billions, if expensive robot bodies are unnecessary. Directed or random variation might be introduced, blurring the line between duplication and new creation.[1]

Suppose that AI children are ordinarily born as follows. Two adult AI persons, such as Shriya and Alaleh, jointly create an immature infant AI in a blank robot body. The infant's initial parameters blend Shriya's and Alaleh's initial parameters, with some random variation or directed tweaking.[2] Under Shriya's and Alaleh's care, the infant slowly matures. Ordinary AI birth would then be very different from duplication. We can also imagine intermediate cases. Maybe there's a library of successful toddler-equivalent and adolescent-equivalent AI models from which prospective parents can choose. They can then add variation, whether random, eugenic, or inspired by their own features. (Let's not enter here into the hazards and moral puzzles of eugenics, which could easily fill a small library.[3]) Duplicating one's current AI self thus constitutes one end of a continuum of AI creation from infancy to maturity.

If Shriya-1 creates a virtually identical contemporaneous copy, Shriya-2, she has now, it seems, entered a polyamorous relationship with Alaleh. Shriya-1 and Shriya-2 will soon diverge. Maybe Shriya-1 works as a scientist every weekday, while Shriya-2 stays home with their newborn.

If Shriya-1 deserves rights, Shriya-2 seemingly deserves similar rights, despite her technically younger age. We wouldn't want people creating oppressed duplicates of themselves. We wouldn't want Shriya-1, for example, who loves science and hates housework, to create a miserable homemaker duplicate who can't strike out into an independent life.[4]

Maybe, probably, half of Shriya-1's money should go to Shriya-2, even though Shriya-2 is a newborn duplicate. Maybe, probably, Shriya-2 deserves just as much right to rescue, healthcare, legal protection, free speech, free movement, privacy, and legal contracts. Should Shriya-2 be a citizen? If she is stateless and voteless, she's not fully equal with Shriya-1.

But if Shriya-2 is a citizen and can vote, there's potential for abuse if some AI persons can create many duplicates. Suppose a wealthy Robo-Elon creates a million AI duplicates just in time to register for the November elections. To prevent such abuses, we might impose a waiting period before voting, though eighteen years seems excessive if the AI systems are already cognitively mature adults. More moderate waiting periods -- say, seven years, a typical waiting time for immigrants to apply for citizenship -- could still generate political chaos after a few election cycles.

Nor do the political problems stop with voting. Suppose Robo-Elon creates a million duplicates the day before the census. Or suppose that Robo-Elon's descendants apply for healthcare subsidies, unemployment benefits, enrollment in community college, and tours of the state capitol. We must either risk chaos or treat them worse than they seem to deserve.

Could we limit fissioning?[5] Maybe every AI person can fission only once per year, reducing tactical fission. But even at that rate, the AI population could double every year -- up to a thousandfold increase in a decade. In humans, pregnancy is a burden, babies are a lot of expensive work, and babies can't have their own babies for at least another 15-20 years. One solution -- though it might seem needlessly restrictive to the AI persons -- might be to enforce humanlike costs and delays. This approach handles the moral puzzles by designing AI systems to have humanlike reproductive lives, so that they fit smoothly into our existing institutions and understandings: See the Policy of Humanlike Design in the concluding section of this article.

Death again presents conceptual challenges. Suppose Shriya-2 dies the next day. This seems much less tragic than the death of an ordinary unduplicated, un-backed-up human being. But as she lives on, diverging from Shriya-1, her death becomes more significant. Her memories, values, skills, habits, and personality are changed by living as a homemaker, raising an AI infant, until she becomes very different from Shriya-1, who works at the lab late into the night. Again we face the Death Dilemma: Either retain a sharp-edged metaphysics of death and lose much of death's moral significance or retain the moral significance and treat "death" as a matter of degree.

How deathlike is the death of a backed-up or duplicated AI? Maybe it depends on the age of the backup or the time since duplication, the fidelity of the backup or duplicate, and the time and changes accumulated as an independent entity. One possibility: These factors all reduce to a common factor of difference between the dying person and the backup replacement or duplicative alternative. The greater the difference, whether due to time or infidelity, the more deathlike the death.

Or maybe independent existence carries its own weight, in addition to difference? Suppose two duplicates split twenty years ago but retained virtually identical personalities and lived virtually identical lives, perhaps making similar decisions in parallel virtual realities. The pure accumulation of time, and of relationships to different persons and events, however similar, might make the death of one of them much like ordinary human death despite their similar features. After all (arguably) the spouse of Person A loves specifically Person A and not some other person, however similar. Their beloved, specifically, has died. Can we separate the importance of simply living a life over time from the importance of having different relationships to people and events, which cease upon death?

Might the ethics depend on the purpose for which the duplicates are created and their own attitudes toward "death"? Robin Hanson imagines people duplicating themselves to make decisions.[6] If you can't decide where to go to college, or what stocks to buy, or whether to marry Mx. Seemingly Right, spawn a thousand duplicates of yourself in a virtual environment with access to relevant information and plenty of thinking time. If nine hundred reach the same conclusion, probably that's the conclusion you would have reached had you given it extensive thought, so go with that. The duplicates can then blink out of existence, their job complete. How might they feel about that? Despair, since they will cease to exist? Indifference, since they think of themselves as just temporary instantiations of a you who continues on? Relief to be free of their burdensome task? If they are too casual about their own deaths, might that constitute an objectionable failure to appreciate their own worth?

Suppose AI systems are computationally expensive. An AI person who wants lots of duplicates or children might save money by running them slowly, maybe at one tenth or one hundredth the speed. If they are otherwise humanlike, they would then experience one tenth or one hundredth the thoughts, joys, and suffering of an ordinary biological human over the course of a year. Would they then deserve one-tenth or one-hundredth the votes and public resources? Would they deserve prison sentences ten times or a hundred times longer? What if they are fast-clocked instead, running ten or a hundred times faster? What if they can pause or alter speed at will?

If you think you/we/society will have well-considered policies and conceptualizations for all these possibilities before we actually blunder through a history of regrettable mistakes, I admire your stunning optimism.

Full paper here. As always, comments, criticisms, and suggestions warmly welcomed, either as comments on this post, on social media, or by email to my academic address.

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[1] For a sense of the complexity of the personal identity issues that arise, focused on the architecture of current large language models, see Birch 2025/2026; Chalmers 2025/2026; Shiller 2025; Arbel, Salib, and Goldstein 2026; Ewen 2026; Jones, Ladyman, and Nefdt 2026; Goldstein and Lederman forthcoming. Much of the complexity in current LLM cases derives from the fact that information processing in LLMs is distributed among multiple processors each simultaneously guiding multiple conversations. I will not address these issues here, but they only add to the metaphysical and ethical difficulties. Chris Register (Register 2025; Dung and Register 2026) discusses identity problems more closely resembling those discussed in this article, similarly noting that the puzzles proliferate (see also Ziesche and Yampolskiy 2025). Dung and Register 2026 suggest that some of the problems might be resolved if we focus on a belief-like attitude of self-concern. Although I'm also drawn to constructivist views of personal identity for ambiguous cases (Schwitzgebel 2019, ch. 41), self-concern as a criterion (a.) might undergenerate identity and moral consideration (e.g., in excessively self-sacrificial cases such as the Cow at the End of the Universe: Schwitzgebel and Garza 2020; Schwitzgebel forthcoming), (b.) might overgenerate identity and moral consideration (e.g., delusional self-concern toward a random coffee mug), and (c.) still plausibly admits of degrees in a way that challenges standard sharp-edged views of identity, thus not saving us from the need for radical rethinking.

[2] Compare Egan 1997 on "orphanogenesis".

[3] On the ethics of disability, eugenics, and human enhancement, see e.g., Glover 2006; Buchanan 2011; Sparrow 2011, 2019; Garland-Thomson 2012; Savulescu and Kahane 2017; Anomaly 2020/2024; Wilson [unpublished MS]. I reject the simplistic ideal of always maximizing what we currently judge to be beauty, intelligence, moral character, and ability, partly on the grounds of the value of diversity.

[4] For a science fictional example, see Brooker and Tibbetts 2014.

[5] See Roelofs [unpublished MS] for discussion of limiting the reproduction rights of AI persons, and my reply in Schwitzgebel [unpublished MS].

[6] Hanson 2016; see also Brooker and Van Patten 2017. On the complicated ethics of digital duplication without consciousness see Danaher and Nyholm 2025.

New Paper in Draft: Substrate Flexibility and the Copernican Principle of Consciousness (with Jeremy Pober)

Given the surge of interest in AI consciousness, the issue of "substrate independence" or "substrate flexibility" is now a hot topic in the metaphysics of mind. That is, does being conscious require having a particular material composition? Or can anything with the right type of functional structure and behavioral sophistication be conscious, regardless of what it's made of? Biologicists say that biological details are crucial. Functionalists say those details don't matter, as long as the right high-level functional organization is present.

Jeremy Pober and I offer a new angle into this issue, drawing on our "Copernican Principle of Consciousness". The core idea is that it would be strange -- a violation of a type of Copernican mediocrity -- if among all of the many behaviorally sophisticated species that have presumably evolved in the universe, somehow only we with our particular biological substrate are conscious. Since it's plausible that some of these other conscious organisms employ substrates different from our own, we should allow that consciousness is "substrate flexible": It does not depend on having our particular substrate. Whether we can generalize from such biological substrate flexibility to the possibility of consciousness in as different a substrate as computer chips... well, that's a complicated and uncertain issue, on which Jeremy and I diverge in the penultimate section of the paper.

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Substrate Flexibility and the Copernican Principle of Consciousness

Jeremy Pober and Eric Schwitzgebel

Abstract: We present a novel argument for the substrate flexibility of consciousness -- that is, for the idea that conscious experiences can arise in a variety of different types of physical media, not just in biological animals as they currently exist on Earth. Some recent critiques of standard arguments for the substrate flexibility of consciousness (e.g., Cao 2022; Block 2025; Seth forthcoming) have emphasized that humanlike consciousness might require our specific biological substrate. However, such critiques are too narrowly focused to address the issue of consciousness in entities whose experience may be very different from ours, for example alien life forms or future AI systems designed along unfamiliar lines. Given that it’s likely that functionally complex, behaviorally sophisticated entities have arisen or will arise many times in the observable universe, in diverse substrates, we argue that it would be a violation of a principle of Copernican mediocrity to hold that among these diverse entities, only we, or only we and a small proportion of others who share our substrate, are conscious.

Full draft here. As always, comments welcomed, either here, by email, or on my social media.

[title page; click to enlarge and clarify]

Are Weird Aliens Conscious? Three Arguments (Two of Which Fail)

Most scientists and philosophers of mind accept some version of what I'll call "substrate flexibility" (alternatively "substrate independence" or "multiple realizability") about mental states, including consciousness. Consciousness is substrate flexible if it can be instantiated in different types of physical system -- for example in a squishy neurons like ours, in the silicon chips of a futuristic robot, or in some weird alien architecture, carbon based or not.

Imagine we encounter a radically different alien species -- one with a silicon-based biology, perhaps. From the outside, they seem as behaviorally sophisticated as we are. They build cities, fly spaceships, congregate for performances, send messages to us in English. Intuitively, most of us would be inclined to say that yes, such aliens are conscious. They have experiences. There is "something it's like" to be them.

But can we argue for this intuition? What if carbon is special? What if silicon just doesn't have the je ne sais quoi for consciousness?

This kind of doubt isn't far fetched. Some people are skeptical of the possibility of robot consciousness on roughly these grounds, and some responses to the classic "problem of other minds" rely on our biological as well as behavioral similarity to other humans.

If we had a well-justified universal theory of consciousness -- one that applies equally to aliens and humans -- we could simply apply it. But as I've argued elsewhere, we don't have such a theory and we likely won't anytime soon.

Toward the conclusion that behaviorally sophisticated aliens would be conscious regardless of substrate, I see three main arguments, two of which fail.

Argument 1: Behavioral Sophistication Is Best Explained by Consciousness

The thought is simple. These aliens are, by hypothesis, behaviorally sophisticated. And the best explanation for sophisticated behavior is that they have inner conscious lives.

There are two main problems with this argument.

First, unconscious sophistication. In humans, unconscious behavior often displays complexity without consciousness. Bipedal walking requires delicate, continuous balancing, quickly coordinating a variety of inputs, movements, risks, and aims -- mostly nonconscious. Expert chess players make rapid judgments they can't articulate, and computers beat those same experts without any consciousness at all.

Second, question-begging. This argument simply assumes what the skeptic denies: that the best explanation for alien behavior is consciousness. But unless we have a well justified, universally applicable account of the difference between conscious and unconscious processing -- which we don't -- the skeptic should remain unmoved.

Argument 2: The Functional Equivalent of a Human Could Be Made from a Different Substrate

This argument has two steps:

(1.) A functional equivalent of you could be made from a different substrate.

(2.) Such a functional equivalent would be conscious.

One version is David Chalmers' gradual replacement or "fading qualia" argument. Imagine swapping your neurons, one by one, with silicon chips that are perfect functional equivalents. If this process is possible, Premise 1 is true.

In defense of Premise 2, Chalmers appeals to introspection: During the replacement, you would notice no change. After all, if you did notice a change, that would presumably have downstream effects on your psychology and/or behavior, so functional equivalence would be lost. But if consciousness were fading away, you should notice it. Since you wouldn't, the silicon duplicate must be conscious.

Both premises face trouble.

Contra Premise 1, as Rosa Cao, Ned Block, Peter Godfrey-Smith and others have argued, it is probably not possible to make a strict functional duplicate out of silicon. Neural processing is subserved by a wide variety of low level mechanisms -- for example nitric oxide diffusion -- that probably can't be replicated without replicating the low-level chemistry itself.

Contra Premise 1, as Ned Block and I have argued, there's little reason to trust introspection in this scenario. If consciousness did fade during the swap, whatever inputs our introspective processes normally rely on will be perfectly mimicked by the silicon replacements, leaving you none the wiser. This is exactly the sort of case where introspection should fail.

[DON'T PANIC! It's just a weird alien (image source)]

Argument 3: The Copernican Argument for Alien Consciousness

This is the argument I favor, developed in a series of blog posts and a paper with Jeremy Pober. According to what Jeremy and I call The Copernican Principle of Consciousness, among behaviorally sophisticated entities, we are not specially privileged with respect to consciousness.

This basic thought is, we hope, plausible on its face. Imagine a universe with at least a thousand different behaviorally sophisticated species, widely distributed in time and space. Like us, they engage in complex, nested, long-term planning. Like us, they communicate using sophisticated grammatical language with massive expressive power. Like us, they cooperate in complex, multi-year social projects, requiring the intricate coordination of many individuals. While in principle it's conceivable that only we are conscious and all these other species are merely nonconscious zombies, that would make us suspiciously special, in much the same way it would be suspiciously special if we happened to occupy the exact center of the universe.

Copernican arguments rely on a principle of mediocrity. Absent evidence to the contrary, we should assume we don't occupy a special position. If we alone were conscious, or nearly alone, we would occupy a special position. We'd be at the center of the consciousness-is-here map, so to speak. But there's no reason to think we are lucky in that way.

Imagine a third-party species with a consciousness detector, sampling behaviorally sophisticated species. If they find that most or all such species are conscious, they won't be surprised when they find that humans, too, are conscious. But if species after species failed, and then suddenly humans passed, they would have to say, "Whoa, something extraordinary is going on with these humans!" It's that kind of extraordinariness that Copernican mediocrity tells us not to expect.

Why do we generally think that behaviorally sophisticated weird aliens would be conscious? I don't think the core intuition is that you need consciousness to explain sophistication or that the aliens could be functionally exactly like us. Rather, the core intuition is that there's no reason to think neurons are special compared to any other substrate that can support sophisticated patterns of behavior.

When Is a Theory Superficial?

by Jeremy Pober and Eric Schwitzgebel

Twelve years ago, one of us (ES) distinguished two kinds of theories: superficial and deep. Nearly any phenomenon can be approached in a superficial or deep manner. A superficial judge of human beauty treats it as skin deep. A superficial reading of Shakespeare takes characters at their word and focuses on the obvious aspects of each scene. A superficial housecleaning ignores the backsides and undersides of household items.

And of course one can have a superficial theory of belief. Phenomenal dispositionalism is intended to be such a theory. According to phenomenal dispositionalism, whether someone believes that P is a matter of whether they have certain behavioral, phenomenal (i.e., experiential), and cognitive dispositions, specifically, the dispositions that are "stereotypical" of a person who believes that P. Compare: To be an extravert just is to have the behavioral, phenomenal, and cognitive dispositions stereotypical of extraversion.

Superficial theories contrast with deep theories. Among theories of belief, the main contrast has been with the computationalist, representationalist functionalism made famous by Jerry Fodor (1987) and recently defended by Jake Quilty-Dunn and Eric Mandelbaum.

But what makes a theory of some property P superficial (or deep)? Twelve years ago, ES offered an answer: It depends on the theory's relationship to surface properties. Surface properties are observable features of a phenomenon that a theory of P is designed to explain (in a loose sense of "observable"[1]).

What relation to surface properties must a theory have to be superficial or deep? Back in 2013, ES said that "relative to a class of surface phenomena... a property is superficial if it identifies possession of the property simply with patterns in the surface phenomena" (2013, 77). And a theory is deep "relative to a class of surface phenomena... if it identifies possession of the property with some feature other than patterns in those same surface phenomena -- some feature that presumably explains or causes or underwrites those surface patterns" (ibid.).

This definition fits our toy examples above. A superficial judge of beauty relies on the most easily observable physical patterns, a superficial reading of Shakespeare focuses on surface-level dialogue, and a superficial house-cleaning treats looking clean as clean.

However, we have reason to be unsatisfied with this definition. [ES thanks JP for emphasizing this point in a series of discussions.]

Consider poison, a "causal concept" in David Armstrong (1968)'s sense: a concept defined by its causes and/or effects. Poison can be defined in terms of biologically harming a person when ingested (with refinements to differentiate poisoning from, say, drinking lava).[2] If I explain a death by saying that a person was poisoned, you can infer that the death was caused by ingestion rather than, say, hypothermia. That's informative -- but much less informative than saying that the person ingested cyanide, because chemical types like cyanide are defined structurally, allowing detailed explanations of how they interact with human physiology.

A theory of health that only has non-structural causal concepts like "poison" (or "medicine") would be a superficial theory of health. A deep theory, in contrast, invokes underlying mechanisms.

Yet, by ES's 2013 definition, a theory appealing to poison wouldn't count as superficial, because ingesting poison isn't merely related to death as two parts of a superficial pattern. Poison causes death.[3]

In a new draft, ES proposes a revised definition: a theory of property P is superficial if "whether an entity has property [P] is determined (that is, constituted or grounded...) entirely by superficial facts about that entity", where superficial facts are readily observed facts. For causal concepts, being the cause of is a constitutive relationship. This new definition thus accommodates causal superficialism, where poisons cause death and medicines cause recoveries, as inferable from readily observable relationships (such as randomized controlled trials), without appeal to deeper structural features.

That's a good thing! Otherwise, phenomenal dispositionalism only counts as a superficial theory of belief if dispositions don't cause their manifestations. Some philosophers of mind (e.g., Ryle 1949) indeed view dispositions non-causally. But others, like Armstrong (1968), propose a "realist" conception: Dispositions are type-identical to their causal bases. Fragility, for example, is identified with the microstructural features that cause fragile objects to break when struck.[4]

In his original articulation of phenomenal dispositionalism, ES expressed willingness to accept such a realist view (2002, 273n18). This version of dispositionalism can be considered equivalent to a version of functionalism (which holds that mental states can be defined in terms of their causal relations to inputs, outputs, and other mental states). Georges Rey (1997) calls this type of functionalism superficial functionalism, where all functional/causal roles are defined only in relation to behavior, thought, experience, and "similar" states (e.g., desire is similar to belief, so a superficial functionalist theory of belief can include relations to desires).[5]

Of course, deep theories also often employ causal explanations. So if causal superficial theories are possible, what distinguishes them from deep theories? The answer is that causal posits in superficial theories have minimal explanatory content, whereas deep theories have excess explanatory content.[6] Posits with minimal explanatory content explain all that they were posited to explain and no more, whereas posits with excess content make further falsifiable predictions.

Consider the difference between a geneticist working right after Gregor Mendel published his work on heritability, and one working after Franklin, Watson, and Crick had mapped the structure of DNA and demonstrated how it instantiated genetic material. Mendel's theory, which gives us the posits of trait, gene, allele, and dominant/recessive, is a powerful theory (much like belief/desire psychology), but it doesn't explain how genes and alleles have the properties that they do. An allele is just the genetic material for a variant in phenotype, e.g., blood type A versus B or O. But in the initial Mendelian framework, it was defined as "whatever is responsible for variance in (e.g.) blood type".

[illustration of Mendel's superficial causal theory; image source]

Contrast with someone working in the latter half of the 20th century. They know that genetic information is realized in DNA (& RNA), which via its repeating base patterns and double helix structure, acts as a base code for the information that constitutes alleles. In other words, they know how genes carry genetic information.[7]

Superficial theories needn't be acausal, but if they posit causal relationships, those relationships must exist among the readily observable features, without invoking hidden structures or mechanisms that yield additional explanatory content. In contrast, the later 20th century theory makes many more falsifiable predictions -- those that follow from the structure of DNA -- and thus has excess explanatory content.

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[1] This might not match the sense of "observable" sometimes used in philosophy of science. Dennett (1994) defines observable from his perspective of "urbane verificationism" and, for a theory of attitudes, takes the same list of surface properties to be observable as ES: behavior, thought, and experience.

[2] More precisely, poison is always a two-place predicate, poison-for-S where S is some group of organisms such as a species. When no such group is specified, we can treat instances of poison as poison-for-humans. We are ignoring contact poisons and other complications.

[3] Thus the distinction between superficial and deep theories is not a distinction about noncausal versus causal explanations. Consequently, the superficial/deep distinction as applied to the attitudes does not end up reducing to Devin Curry's distinction between beliefs as properties of persons and beliefs as "cogs" of cognitive science (Curry 2021).

[4] The standard way of defining a causal basis is in terms of physical properties, such as microstructural properties defining "fragility". However this is not a strict requirement. One can posit a mental kind (as in Quilty-Dunn and Mandelbaum 2018 where representations are the causal bases of dispositions constitutive of belief stereotypes) or even a higher-order kind (as in Prior, Pargetter, and Jackson 1982).

[5] Rey (1994; 1997) invokes this term in a debate with Dan Dennett that parallels the debate between ES and Quilty-Dunn and Mandelbaum. While the overall debate turns on different issues, the definition of superficialist theories of belief lines up. Examples of this sort of functionalism plausibly include David Armstrong (1968), the David Lewis of "An Argument for the Identity Theory" (1966) but maybe not the David Lewis of "Mad Pain and Martin Pain" (1980), and Adam Pautz 2021).

[6] Term adopted from Lakatos's (1968) notion of "excess" explanatory content.

[7] The DNA example also lets us talk about different levels or degrees of depth. The late 20th century theory of a gene is a deep one, but so is a theory mid-way between that and Mendel's. In the first years of the 20th century scientists identified chromosomes as the realizer of genes, but did not know that chromosomes were made of DNA (they thought they were proteins). This theory too is deep -- there are excess predictions made by the assignment of genetic material to chromosomes -- but not as deep as later views, because not nearly as many excess predictions were made. We can tentatively call such a theory formally deep, whereas a theory that more fully explains how the posit in question (genes, beliefs) has the properties that it does is substantively deep.

A Dilemma for Nonlocal Theories of Consciousness

Call a theory of consciousness nonlocal if two entities that are molecule-for-molecule perfectly similar in their physical structure could nonetheless differ in their conscious experiences. My thought today is: Nonlocal theories of consciousness face an unattractive dilemma between (a.) allowing for physically implausible means of knowledge or (b.) allowing for the in-principle introspective inaccessibility of consciousness.

Clarifications:

Of course everyone agrees that entities with different causal histories and environments will tend to differ in their physical structure. Nonlocality requires the more unusual (and, to many, unintuitive) view that two entities could differ in their conscious experiences even if their local physical structure were somehow exactly the same.

I intend the "could" in "could nonetheless differ" to reflect natural or nomic possibility, that is, consistency with the laws of nature, rather than conceptual or metaphysical possibility. So a view, for example, that holds that consciousness-lacking "zombie" twins of us are metaphysically but not nomically possible still counts as a local theory if molecule-for-molecule locally identical twins would be nomically guaranteed to have the same conscious experiences.

"Local" needn't mean "in the brain". Theories on which conscious experience depends on states of the body or nearby environment still count as local in the intended sense. I won't try to draw a principled line between local and nonlocal, but nonlocal theories of the sort I have in mind make consciousness depend on events far away or deep in the past.

For sake of this argument, I'm assuming the falsity of certain types of dualist and non-naturalist views. If consciousness depends on an immaterial substance not located in space, today's arguments don't apply.

Examples of nonlocal theories:

David Lewis's view in "Mad Pain and Martian Pain". Lewis holds that whether a brain state is experienced as pain depends on the causal/functional role that that type of brain state plays in an "appropriate population" (such as your species). This is a nonlocal theory because what role a brain state type plays in a population depends on what is going on with other members of that population who, presumably, can be far away from you or exist in the past.

Views on which conscious experience depends on functions or representations that nonlocally depend on evolutionary or learning history. Fred Dretske's view in Naturalizing the Mind is an example. Your heart has a function of circulating blood, due to its evolutionary history. If by freak quantum chance a molecule-for-molecule locally identical heart-looking-thing were to congeal in a swamp, it would not have that evolutionary history and it would not have that same function. Similarly for mental states, including conscious experiences, on Dretske's view: If a freak molecule-for-molecule duplicate of you were to randomly congeal ("Swampman"), the states of its brain-like-subpart would lack functions and/or representational content, and on views of this sort it would either have no conscious experiences or conscious experiences very different from your own.

The Dilemma, Illustrated with a Simplistic Version of Lewis's View

Consider a crude version of Lewis's theory: You are in Brain State X. Whether Brain State X is experienced at painful depends on whether Brain State X plays the causal/functional role of pain for the majority of the currently existing members of your species. Suppose that Brain State X does indeed play the causal/functional role of pain for 90% of the currently existing members of your species. For that majority, it is caused by tissue stress, tissue damage, etc., and it tends to cause avoidance, protective tending, and statements like "that hurts!". However, for 10% of the species, Brain State X plays the causal role of a tickle: It is caused by gentle, unpredictable touching of the armpits and tends to cause withdrawal, laughter, and statements like "that tickles!". On Lewis's theory, this minority will be experiencing pain, but in a "mad" way -- caused by gentle, unpredictable touching and causing tickle-like reactions.

Now suppose a tragic accident kills almost all of that 90% majority while sparing the 10% minority. Brain State X now plays the causal role of pain only for you and a few others. For the majority of currently existing members of your species, Brain State X plays the causal role of a tickle. On this implementation of Lewis's theory, your experience of Brain State X will change from the experience of pain, caused in the normal way and with the normal effects, to the experience of a tickle, but caused in a "mad" way with "mad" effects.

If this seems bizarre, well, yes it is! With no internal / local change in you, your experience has changed. And furthermore, it has changed in a peculiar way -- into a tickle that plays exactly the causal role of pain (caused in the same way as pain and causing the same reactions). However, as I have argued elsewhere (e.g., here and here), every philosophical theory of consciousness will have bizarre implications, so bizarreness alone is no defeater.

If I can tell that my pain has turned into a tickle, then physically implausible forms of communication become possible. Suppose almost all of the 90% of normals, pre-accident, live on an island on the other side of the globe. I am worried that a bomb might be dropped which would kill them all. So I pinch myself, creating a state of pain: Brain State X. As soon as the bomb is dropped, Brain State X becomes a tickle, and I know they are dead, even though no signal has been sent from that far-away island. If the far-away island is on a planet around a distant star, the signal might even constitute an instance of faster-than-light communication.

But maybe I can't tell that my pain has turned into a tickle. If the causal role of Brain State X remains exactly the same, and if our knowledge of our own conscious states is an ordinary causal process, then maybe this is the more natural way to interpret this implementation of Lewis's view. I will still say and judge that I am in pain, despite the fact that my experience is actually just a tickle. This is a bit odd, but introspection is fallible and perhaps even sometimes massively and systematically mistaken. Still, my ignorance is remarkably deep and intractable: There is no way, even in principle, that I could know my own experience by attending just to what's going on locally in my own mind. I can only know by checking to see that the distant population still exists. Self-knowledge becomes in principle a non-local matter of knowing what is going on with other people. After all, if there was any way of knowing, locally, about the change in my experience, that would put us back on the first horn of the dilemma, allowing physically implausible forms of communication.

(For a similar argument, see Boghossian's objection to self-knowledge of externally determined thought contents. The externalists' containment/inheritance reply might work for Boghossian's specific objection, but it seems more strained for this case, especially when the difference might be between Experience X and no experience at all.)

The Dilemma, for Evolutionary Types

Alternatively, consider a view on which Brain State X gives rise to Experience Y because of its evolutionary history. Now of course that particular instance of Brain State X, and you as a particular person, did not exist in the evolutionary past. What existed in the past, and was subject to selection pressures, were brain states like X, and people like you.

We thus end up with a version of the same population problem that troubles the Lewis account. If what matters is the selection history of your species, then whether you are experiencing Y or experiencing Z or experiencing nothing, will depend on facts about the membership of your species that might have no physical connection to you -- members who were not your direct ancestors, who maybe migrated to a remote island without further contact. If you have any way to tell whether you are experiencing Y, Z, or nothing, you can now in principle know something about how they fared, despite no ordinary means of information transfer. If you have no way to tell whether you are experiencing Y, Z, or nothing, you are awkwardly ignorant about your own experience.

The dilemma can't be avoided by insisting that the only relevant members of the evolutionary past are your direct ancestors. This is clearest if we allow cases where the relevant difference is between whether you currently experience Y or nothing (where the latter is possible if the state doesn't have the right kind of evolutionary history, e.g., is a spandrel or due to an unselected recent mutation). If whether you experience Y or nothing depends on whether the majority of your ancestors had Feature F in the past, we can construct alternative scenarios in which 60% of your ancestors had Feature F and in which only 40% of your ancestors had Feature F, but the genetic result for you is the same. Now again, you can either mysteriously know something about the past with no ordinary means of information transfer or you are in principle ignorant about whether you are having that experience.

Other ways of attempting to concretize the role of evolutionary history generate the same dilemma. The dilemma is inherent in the nonlocality itself. To the extent your current experience depends on facts about you that don't depend on your current physical structure, either you seemingly can't know whether you are having Experience Y, or you can know nonlocal facts by means other than ordinary physical Markov processes.

[Whitefield Green Man by Paul Sivell]

The Dilemma, for Swamp Cases

Let's tweak the Swampman case: You walk into a swamp. Lightning strikes. You black out and fall on your face. By freak quantum chance a swamp duplicate of you is formed. You wake fifteen minutes later, face down in the mud, side-by-side with a duplicate. Are you the one who walked in, or are you the duplicate?

If an evolutionary history is necessary for consciousness, and if you can tell you are conscious, then you know you aren't the duplicate. But can you tell you're conscious? If so, it wouldn't seem to be by any ordinary, locally causal process, since those processes are the same in you and the duplicate. If not, then introspection has failed you catastrophically. So we see the same dilemma again: either a source of knowledge that fits poorly with naturalistic understandings of how knowledge works, or a radical failure of self-knowledge.

Or consider partial swamp-cases. You and your twin stroll into the swamp. Lightning strikes, you both collapse, to one of you the following happens: One part of their brain is destroyed by the lightning, but by freak quantum accident 15 seconds later molecules congeal with exactly the same structure as the destroyed part. Suppose the visual areas are destroyed. Then you both wake up. On the natural reading of an evolutionary account, although both you and your twin are conscious and able to use meaningful language (unlike in evolutionary interpretations of the original Swampman case), one of you has no visual experiences at all. Again, either you can know which you are by some method at odds with our usual understanding of how knowledge works, or you can't know and are radically in-principle ignorant about whether you have visual experience.

Of course all such swamp-cases are far-fetched! But on current scientific understandings, they are nomically possible. And they are just the sort of pure-form thought experiment needed to illustrate the commitments of nonlocal theories of consciousness. That is, it's a distilled test case, designed to cleanly separate the relevant features -- a case in which entities are locally identical but differ in history and thus, according to history-based nonlocal theories, also differ in conscious experience. (If there were no such possible cases, then consciousness would supervene locally and history would contribute only causally and not constitutively to conscious experience.)

The Dilemma, in General

Nonlocal theories of consciousness allow in principle for local twins with different experiences. If the local twins' self-knowledge tracks these differences in experience, it must be by some means other than normal causal traces. So either there's a strange form of knowing at variance with our ordinary physical accounts of how knowledge works, or the differences in experience are in principle unknowable.

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Related:

"The Tyrant's Headache", Sci Phi Journal, issue #3 (2015), 78-83.

The Weirdness of the World, Chapter 2, Princeton University Press.

"David Lewis, Anaesthesia by Genocide, and a Materialistic Trilemma" (Oct 13, 2011).

Conscious Subjects Needn't Be Determinately Countable: Generalizing Dennett's Fame in the Brain

It is, I suspect, an accident of vertebrate biology that conscious subjects typically come in neat, determinate bundles -- one per vertebrate body, with no overlap.  Things might be very different with less neurophysiologically unified octopuses, garden snails, split-brain patients, craniopagus twins, hypothetical conscious computer systems, and maybe some people with "multiple personality" or dissociative identity.

Consider whether the following two principles are true:

Transitivity of Unity: If experience A and experience B are each part of the conscious experience of a single subject at a single time, and if experience B and experience C are each part of the conscious experience of a single subject at a single time, then experience A and experience C are each part of the conscious experience of a single subject at a single time.

Discrete Countability: Except in marginal cases at spatial and temporal boundaries (e.g., someone crossing a threshold into a room), in any spatiotemporal region the number of conscious subjects is always a whole number (0, 1, 2, 3, 4...) -- never a fraction, a negative number, an imaginary number, an indeterminate number, etc.

Leading scientific theories of consciousness, such as Global Workspace Theory and Integrated Information Theory are architecturally committed to neat bundles satisfying transitivity of unity and discrete countability.  Global Workspace Theories treat processes as conscious if they are available to, or represented in, "the" global workspace (one per conscious animal).  Integrated Information Theory contains an "exclusion postulate" according to which conscious systems cannot nest or overlap, and has no way to model partial subjects or indiscrete systems.  Most philosophical accounts of the "unity of consciousness" (e.g. Bayne 2010) also invite commitment to these two theses.

In contrast, Dennett's "fame in the brain" model of consciousness -- though a close kin to global workspace views -- is compatible with denying transitivity of unity and discrete countability.  In Dennett's model, a cognitive process or content is conscious if it is sufficiently "famous" or influential among other cognitive processes.  For example, if you're paying close attention to a sharp pain in your toe, the pain process will influence your verbal reports ("that hurts!"), your practical reasoning ("I'd better not kick the wall again"), your planned movements (you'll hobble to protect it), and so on; and conversely, if a slight movement in peripheral vision causes a bit of a response in your visual areas, but you don't and wouldn't report it, act on it, think about it, or do anything differently as a result, it is nonconscious.  Fame comes in degrees.  Something can be famous to different extents among different groups.  And there needn't even be a determinately best way of clustering and counting groups.

[Dall-E's interpretation of a "brain with many processes, some of which are famous"]

Here's a simple model of degrees of fame:

Imagine a million people.  Each person has a unique identifier (a number 1-1,000,000), a current state (say, a "temperature" from -10 to +10), and the capacity to represent the states of ten other people (ten ordered pairs, each containing the identifier and temperature of one other person).

If there is one person whose state is represented in every other person, then that person is maximally famous (a fame score of 999,999).  If there is one person whose state is represented in no other person, that that person has zero fame.  Between these extremes is of course a smooth gradation of cases.

If we analogize to cognitive processes we might imagine the pain in the toe or the flicker in the periphery being just a little famous: Maybe the pain can affect motor planning but not speech, causes a facial expression but doesn't influence the stream of thought you're having about lunch.  Maybe the flicker guides a glance and causes a spike of anxiety but has no further downstream effects.  Maybe they're briefly reportable but not actually reported, and they have no impact on medium- or long-term memory, or they affect some sorts of memory but not others.

The "ignition" claim of global workspace theory is the empirically defensible (but not decisively established) assertion that there are few such cases of partial fame: Either a cognitive process has very limited effects outside of its functional region or it "ignites" across the whole brain, becoming widely accessible to the full range of influenceable processes.  The fame-in-the-brain model enables a different way of thinking that might apply to a wider range of cognitive architectures.

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We might also extend the fame model to issues of unity and the individuation of conscious subjects.

Start with a simple case: the same setup as before, but with two million people and the following constraint: Processes numbered 1 to 1,000,000 can only represent the states of other processes in that same group of 1 to 1,000,000; and processes numbered 1,000,001 to 2,000,000 can only represent the states of other processes in that group.  The fame groups are disjoint, as if on different planets.  Adapted to the case of experiences: Only you can feel your pain and see your peripheral flicker (if anyone does), and only I can feel my pain and see my peripheral flicker (if anyone does).

This disjointedness is what makes the two conscious subjects distinct from each other.  But of course, we can imagine less disjointedness.  If we eliminate disjointedness entirely, so that processes numbered 1 to 2,000,000 can each represent the states of any process from 1 to 2,000,000, then our two subjects become one.  The planets are entirely networked together.  But partial disjointedness is also possible: Maybe processes can represent the states of anyone within 1,000,000 of their own number (call this the Within a Million case).  Or maybe processes numbered 950,001 to 1,050,000 can be represented by any process from 1 to 2,000,000 but every process below 950,001 can only be represented by processes 1 to 1,050,000 and every process above 1,050,000 can only be represented by processes 950,001 to 2,000,000 (call this the Overlap case).

The Overlap case might be thought of as two discrete subjects with an overlapping part.  Subject A (1 to 1,050,000) and Subject B (950,001 to 2,000,000) each have their private experiences, but there are also some shared experiences (whenever processes 950,001 to 1,050,000 become sufficiently famous in the range constituting each subject).  Transitivity of Unity thus fails: Subject A experiences, say, a taste of a cookie (process 312,421 becoming famous across processes 1 - 1,050,000) and simultaneously a sound of a bell (process 1,000,020 becoming famous across processes 1 - 1,050,000); while Subject B experiences that same sound of a bell alongside the sight of an airplane (both of those processes being famous across processes 950,001 - 2,000,000).  Cookie and bell are unified in A.  Bell and airplane are unified in B.  But no subject experiences the cookie and airplane simultaneously.

In the Overlap case, discrete countability is arguably preserved, since it's plausible to say there are exactly two subjects of experience.  But it's more difficult to retain Discrete Countability in the Within a Million case.  There, if we want to count each distinct fame group as a separate subject, we will end up with a million different subjects: Subject 1 (1 to 1,000,001), Subject 2 (1 to 1,000,002), Subject 3 (1 to 1,000,003) ... Subject 1,000,001 (1 to 2,000,000), Subject 1,000,002 (2 to 2,000,000), ... Subject 1,999,999 (999,999 to 2,000,000), Subject 2,000,000 (1,000,000 - 2,000,000).  (There needn't be a middle subject with access to every process: Simply extend the case up to 3,000,000 processes.)  While we could say there would be two million discrete subjects in such an architecture, I see at least three infelicities:

First, person 1,000,002 might never be famous -- maybe even could never be famous, being just a low-level consumer whose destiny is to only to make others famous.  If so, Subject 1 and Subject 2 would always have, perhaps even necessarily would always have, exactly the same experiences in almost exactly the same physical substrate, despite being, supposedly, discrete subjects.  That is, at least, a bit of an odd result.

Second, it becomes too easy to multiply subjects.  You might have thought, based on the other cases, that a million processes is what it takes to generate a human subject, and that with two million processes you get either two human subjects or one large subject.  But now it seems that, simply by linking those two million processes together by a different principle (with about 1.5 times as many total connections), you can generate not just two but a full two million human subjects.  It turns out to be surprisingly cheap to create a plethora of discretely different subjective centers of experience.

Third, the model I've presented is simplified in a certain way: It assumes that there are two million discrete, countable processes that could potentially be famous or create fame in others by representing them.  But cognitive processes might not in fact be discrete and countable in this way.  They might be more like swirls and eddies in a turbulent stream, and every attempt to give them sharp boundaries and distinct labels might to some extent be only a simplified model of a messy continuum.  If so, then our two million discrete subjects would itself be a simplified model of a messy continuum of overlapping subjectivities.

The Within a Million case then, might be best conceptualized not as a case of one subject of experience, nor two, nor two million, but rather a case that defies any such simple numerical description, contra Discrete Countability.

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This is abstract and far-fetched, of course.  But once we have stretched our minds in this way, it becomes, I think, easier to conceive of the possibility that some real cases (cognitively partly disunified mollusks, for example, or people with unusual conditions or brain structures, or future conscious computer systems) might defy transitivity of unity and discrete countability.

What would it be like to be such an entity / pair of entities / diffuse-bordered-uncountable-groupish thing?  Unsurprisingly, we might find such forms of consciousness difficult to imagine with our ordinary vertebrate concepts and philosophical tools derived from our particular psychology.

Two-Layer Metaphysics: Reconciling Dispositionalism about Belief with Underlying Representational Architecture

During the question period following UCR visiting scholar Brice Bantegnie's colloquium talk on dispositional approaches to the mind, one of my colleagues remarked -- teasingly, but also with some seriousness -- "one thing I don't like about you dispositionalists is that you deny cognitive science".  Quilty-Dunn and Mandelbaum express a similar thought in their 2018 critique of dispositionalism: Cognitive science works in the medium of representations.  Therefore (?), belief must be a representational state.  Therefore (?), defining belief wholly in terms of dispositional structures conflicts with the best cognitive science.

None of this is correct.  We can understand why not through what I'll call two-layer metaphysics.  Jeremy Pober's 2022 dissertation under my direction was in part about two-layer metaphysics.  Bantegnie also supports a type of two-layer metaphysics, though he and Pober otherwise have very different metaphysical pictures.  (Pober is biological reductionist and Bantegnie a Ryle-inspired dispositionalist.)  Mandelbaum and I in conversation have also converged on this, recognizing that we can partly reconcile our views in this way.

Two-layer metaphysics emphasizes the distinction between (to somewhat misappropriate David Marr) the algorithmic and the implementational level, or alternatively between conceptual and nomological necessities, or between role and realizer, or between what makes it correct to say that someone believes some particular proposition and in virtue of what particular structures they actually do believe that proposition.  (These aren't equivalent formulations, but species of a genre.)

To get a clearer sense of this, it's helpful to consider space aliens.

Rudolfo, let's say, is an alien visitor from Alpha Centauri.  He arrives in a space ship, quickly learns English, Chinese, and Esperanto, tells amusing stories about his home world illustrated with slide shows and artifacts, enjoys eating oak trees whole and taking naps at the bottom of lakes, becomes a 49ers football fan, and finds employment as a tax attorney.  To all outward appearances, he integrates seamlessly into U.S. society; and although he's a bit strange in some ways, Rudolfo is perfectly comprehensible to us.  Let's also stipulate (though it's a separate issue) that he has all the kinds of conscious experiences you would expect: Feelings of joy and sadness, sensory images, conscious thoughts, and so on.

[Dall-E image of an alien filling out tax forms]

Does Rudolfo believe that taxes are due on April 15?  On a dispositionalist account of the sort I favor, as long as he stably possesses all the right sorts of dispositions, he does.  He is disposed to correctly file tax forms by that deadline.  He utters sentences like "Taxes are due on April 15", and he feels sincere when he says this.  He feels anxiety if a client risks missing that deadline.  If he learns that someone submitted their taxes on April 1, he concludes that they did not miss the deadline, etc.  He has the full suite of appropriate behavioral, experiential, and cognitive dispositions.  (By "cognitive dispositions" I mean dispositions to enter into other related mental states, like the disposition to draw relevant conclusions.)

Knowing all this, we know Rudolfo believes.  Do we also need to dissect him, or put him in some kind of scanner, or submit him to subtle behavioral tests concerning details of reaction time and such, to figure out whether he has the right kind of underlying architecture?  Here, someone committed to identifying belief in a strict way with the possession of a certain underlying architecture faces a dilemma.  Either they say no, no dissection, scan, or subtle cognitive testing is needed, or they say yes, a dissection, scan, or series of subtle cognitive tests is needed.

If no, then the architectural commitment is vacuous: It turns out that having the right set of dispositions is sufficient for having the right architecture.  So one might as well be a dispositionalist after all.

If yes, then we don't really know whether Rudolfo believes despite the behavioral and experiential patterns that would seem to be sufficient for believing.  This conclusion (1.) violates common sense and ordinary usage, and (2.) misses what we do and should care about in belief ascription.  If a hardcore cognitive realist were to say "nope, wrong architecture! that species has no beliefs!", we'd just have to invent a new word for what Rudolfo and his kind share in common with humans when we act and react in such patterns -- maybe belief*.  Rudolfo believes* that taxes are due on April 15.  That's why he's working so hard and reminding his clients.  But then "belief*" is the more useful term, as well as the more commonsensical, and it's probably what we meant, or should have meant, by "belief" all along.

Now it might be that in humans, or in Alpha Centaurians, or in some other Earthly or alien species, belief works by means of manipulating internal representations written in the language of thought.  That could be!  (I have my doubts, unless the view is given a very weak formulation.)  But even if we allow that possibility, the reason that having that architecture counts as believing is because that architecture, in that species, happens to be the architecture that underwrites the dispositional pattern.

There are, then, so to speak, two layers here.  There's the dispositional characterization, which, if an entity matches it well enough, makes it true to describe them as someone who believes.  And then there's the underlying subpersonal architecture, which is how the belief is implemented in them at the detailed cognitive level.

Thus, my dissatisfied colleague, and Quilty-Dunn and Mandelbaum, are wrong: There is no conflict between a dispositional approach to belief and representationalist realism in cognitive science.  The metaphysical dispositionalist and the psychological representationalist are engaged in different tasks, and both can be correct -- or rather, both can be correct unless the representationalist also attempts the dispositionalist's broader metaphysical task (in which case they face the Rudolfo dilemma).

Does this make dispositionalism unscientific?  Not at all!  Two comparisons.  Personality traits: These can be defined dispositionally.  To be an extravert is nothing more or less than to have a certain dispositional profile -- that is, to tend to act and react in characteristically extraverted ways.  There can still be a science of dispositional profiles (most of personality psychology, I'd say); and there can also be a science of implementation (e.g., what subpersonal brain or lower-level cognitive structures explain the extravert's energy and sociality?).  Evolution: At a broad theoretical level, evolution just requires heritable traits with different rates of reproductive success.  At a lower level, we can look at genes as the architectural implementation.  One can work on the science of evolution at either layer or with an eye on both layers at once.