A passage from Mark Twain's Connecticut Yankee in King Arthur's Court has been stuck in my head since I read it some 35 years ago:

As for me, all that I think about in this plodding sad pilgrimage, this pathetic drift between the eternities, is to look out and humbly live a pure and high and blameless life, and save that one microscopic atom in me that is truly me: the rest may land in Sheol and welcome for all I care.

That "one atom that is truly me"!

I recognize that there are parts of my body that I wouldn't consider "me," such as my hair or fingernails, or even substantial parts of my limbs if I had to lose them. But if I were to lose large parts of my brain, I would be considerably less myself—it certainly takes more than a single atom.

That's why mental illness is so harrowing, including the impairment that accompanies aging, even when not due to disease. Mere forgetfulness is a gradual way to lose one's self, if personal identity is defined by psychological continuity (that is, "I am the person I was yesterday because I remember being that person yesterday"). HAL's disassembly in 2001 comes to mind, in which his cognitive functions were removed one at a time: "Dave, my mind is going. I can feel it. There is no question about it... I'm afraid, Dave."

Most people, myself included, are inconsistent in the way we talk about compositeness of our selves. We know that our brains are made of parts and have heard of clinical cases in which one part or another gets cut or removed, and then that person forgets what words mean but can still spell, or loses the ability to make new memories but keeps old ones, or acts without social inhibitions, etc. We've heard of cases in which people have two functional brain hemispheres that don't communicate with each other—one half literally doesn't know what the other half is doing. And yet, despite that knowledge, we still talk about to ourselves as atomic beings—atomic in the Greek sense of "indivisible" (ἄτομος) and also in the sense that one being is categorically distinct from another.

A lot of important concepts rest on this idea that we are individuals. In ethics, we want to be able to say, "Alex is the murderer!" to mean that all of Alex, as a whole person, committed the crime of murder and all of Alex, not just half of Alex's brain, should be punished for that act. (Where would we put the rest of him?)

Or on a smaller scale, just to be able to say, "I like spicy food." Maybe there are parts of me that don't like spicy food, and the parts that are in control enjoy torturing the other parts with the pain of the spice—they do seem to struggle and writhe, and that's part of the fun.

Also, it's common—almost instinctive—for people to distinguish between their "true self" and outside influences, particularly to draw an ethical distinction between them. A human animal has all sorts of desires, but the desire to cheat on one's spouse or eat all the cookies are considered forces this human is striving against (unless you already think he's a scoundrel) while the desire to rescue a puppy from drowning is considered his true essence (even if you think he's mostly a scoundrel).

Judeo-Christian religions generally start from the assumption that consciousness is atomic, called a soul. Not only does there need to be an accounting of a soul's goodness, but the entire soul is either saved or damned. Even if we disregard fire-and-brimstone preachers who think of heaven and hell as physical places and damnation as something that happens to you, rather than something you do to yourself, the assumption that a whole soul either comes to a good or a bad end seems inescapable.

Here's an account of hell that I like quite a bit, from C.S. Lewis's The Great Divorce, because it corresponds with living human psychology. However, it still presumes a unity of consciousness:

"That's right. They went up and looked through one of the windows. Napoleon was there all right."

"What was he doing?"

"Walking up and down—up and down all the time—left-right, left-right—never stopping for a moment. The two chaps watched him for about a year and he never rested. And muttering to himself all the time. 'It was Soult's fault. It was Ney's fault. It was Josephine's fault. It was the fault of the Russians. It was the fault of the English.' Like that all the time. Never stopped for a moment. A little, fat man and he looked kind of tired. But he didn't seem able to stop it."

All of Napoleon degenerated into this little spiral, not just a part of him.

There have been other opinions. Manichaeism starts with the idea of two fundamental principles/gods, a good one ("Father of Greatness") and a bad one ("King of Darkness"). The physical world we know is a result of them getting all mixed up, and the work a good person should do on Earth is to separate them, removing the badness from themselves so that the goodness is free to fly away. Manichaeans didn't expect to end up in heaven or hell: they expected parts of themselves to end up in both.

Manichaeism was highly influenced by Buddhism (it was a deliberate combination of Buddhism, Christianity, and Zoroastrianism), and Buddhism famously opposes the concept of a unified self. Sometimes, Buddhists say that any "I" or "me" is an illusion, but in longer explanations, it sounds more like they believe that "I" or "me" is a construct, like a chair is a temporary, nebulous assembly of atoms, or the Mississippi River is a way of saying, "water usually flows here," but doesn't correspond to specific, particular water atoms, and the currents and even course of the river can change.

Buddhists describe sentient beings as five "aggregates, heaps, collections, groupings" (स्कन्ध skandha in Sanskrit), namely form (रूप rūpa), sensations (वेदना vedanā), perceptions (संज्ञा saṃjñā), mental activity (संस्कार saṃskāra), and consciousness (विज्ञान vijñāna). Even broken down like this, I find these words to be vague concepts in English, but I'm assured that it's a precise, technical vocabulary in the original languages. If any one of these heaps is taken away, there's no more person/sentient being, but taken together, the person exists. In an early encounter between Buddhism and the west, Nagasena talked about himself as decomposable like a chariot: a chariot is not its wheels, not its axle, not its seat, and when you remove these pieces, there's no more chariot. (Given that, I wouldn't say that the chariot is an "illusion," but that's a manner of speaking.)

In a similar, but not quite the same way, we can talk about a person being the sum of their hippocampus, amygdala, prefrontal cortex, and so on. HAL is the sum of his (removable) cognitive modules.

You might have noticed that I've come to the conclusion that consciousness is composite (and on this site, I expect most readers to agree), but the consequences of that are hard to swallow. Perhaps it's not too disturbing to get rid of the concept of blame: "Alex is the murderer! Let's punish Alex!" is a retributive concept of justice, and many of us prefer restorative justice, anyway: "Something went wrong and Alex committed murder. Let's fix Alex!" But if there's no blame, then there's no praise, either. When I apply this kind of thinking to myself, I slip into the third person, because "parts of myself that I want to encourage" are described at a greater distance than "me."

And what about when I eat spicy food because it hurts my mouth and I like it when my mouth hurts? If this interaction were happening between two human bodies—one human animal deliberately causing pain in another human animal—then it would be a Bad Situation, the kind that might need some restorative (if not retributive) justice. Splitting the atom of consciousness into consciousness-bits opens at least the possibility that consciousness-bits in different heads are composable in the same sort of way that consciousness in one head is decomposable.

For the past few years, I've been wondering if the idea of atomic consciousness needs to be replaced by another physics-metaphor: nuclear consciousness. Nuclear forces are messy and complicated, yet short-range. Within a proton or neutron, three (valence) quarks attract each other by exchanging gluons, and while the gluons are in flight, they spawn new quark-antiquark pairs that themselves attract each other with yet more gluons. In a popular physics article, I once drew it like this:

Individual protons and neutrons attract each other in a nucleus through a much weaker, fringe-field effect of this interaction. Gluons rarely stray from the quarks that produced them, and protons and neutrons in the nucleus are farther apart than quarks within the nucleus. (For fellow nerds: whereas electric fields fall off like $1/r^2$, gluonic fields fall off like $e^{-r/r_0}/r^2$.) Nuclear forces between particles in different atoms are vanishingly small, but not strictly zero.

The boundaries between quarks-in-protons, protons-in-nuclei, and nuclei of different atoms are not categorically distinct things, but well-separated by quantitatively large magnitudes. To demonstrate the fact that they can be mixed, all of the quarks and gluons of two whole nuclei become a kind of soup if the nuclei are collided hard enough. Here's how I drew that process in another article:

In the very early universe, all of space was filled with a uniform quark-gluon plasma, until it expanded enough that quarks were far apart from each other, and congealed into protons and neutrons.

Now for the metaphor: perhaps the decomposition of consciousness is like the decomposition of protons. A thinking being seems to be a single, indivisible unit like a proton, but if you look inside, you see that it's made of parts. Buddhists in introspective meditation see five aggregates; neuroscientists see brain functions. In Reality and reality-boxes, I emphasized that I consider both of these valid approaches that do not investigate the same sorts of things: introspection reveals the very real subjective reality, and scientific investigation reveals the very real physical reality, which are things that are different enough they should probably have distinct words and not overload the single word "reality."

In addition to a single proton being decomposable, multiple protons are composable: they can be mushed together into a fluid. The non-atomicity of protons goes both ways, below the level of a unit and above it. In this consciousness metaphor, there are subconscious scraps of thoughts and feelings floating around in our heads, and also not-quite-conscious thoughts and feelings flowing through communities: groups of people think. Whereas the parts of my brain are strongly connected, with thick bundles of neural wire between them, the brains of people who live together are weakly connected, through facial expressions, group activities, and words.

Are these two kinds of connection different only in scale, like the direct quark-gluon interactions within a proton and the fringe-fields between them? Maybe. That's the idea I've been tinkering with and calling nuclear, as opposed to atomic, consciousness. We do know there are neurological effects that happen between primates, such as mirror neurons, and natural selection does not respect dividing lines between bodies. When I read about Jung's notion of the collective unconscious, this is how I'm interpreting it. (Interestingly, only the middle level is fully awake: neither lobotomized people nor groups of people act coherently.)

I've long ascribed to (and felt) that people are existentially isolated: that there would be no way to know if the color I see as red is red for you, as long as words matched to distinct things. Like in Wittgenstein's beetle-in-a-box metaphor in Philosophical Investigations:

If I say of myself that it is only from my own case that I know what the word "pain" means—must I not say the same of other people too? And how can I generalize the one case so irresponsibly?

Now someone tells me that he knows what pain is only from his own case! Suppose everyone had a box with something in it: we call it a "beetle." No one can look into anyone else's box, and everyone says he knows what a beetle is only by looking at his beetle. Here it would be quite possible for everyone to have something different in his box. One might even imagine such a thing constantly changing. But suppose the word "beetle" had a use in these people's language? If so it would not be used as the name of a thing. The thing in the box has no place in the language-game at all; not even as a something: for the box might even be empty. No, one can "divide through" by the thing in the box; it cancels out, whatever it is.

That is to say: if we construe the grammar of the expression of sensation on the model of "object and designation" the object drops out of consideration as irrelevant.

But I do believe that parts of my brain know what it's like to be other parts of my brain because the beetle is not hidden from them. Now if the separation among parts of my brain is the same sort of separation as between individuals, maybe we do see inside each other's skulls, to a degree. Nuclear consciousness is a rebuttal against existential isolation in principle—that there's only a larger separation between people than within a person, not a different kind of separation.

I wonder, if telepathy ever becomes possible—through radios deeply wired into our neurons or something—would we still feel like we're talking to each other, as it's depicted in stories about telepathy, or would we feel like we are all one person, as the individual bits of my brain do with each other? Is knowing someone (connaître, not savoir) a small step toward being that someone?

I would like to read a version of Invasion of the Body Snatchers from the perspective of the Pod People. They wanted to communicate with Earthlings, but they're telepathic, so they became the Earthlings...

Even though I think we can rule out atomic consciousness (sorry, Mark Twain), I'm not sure how much it dissolves, how seriously to take the idea that we're all one, loosely connected and barely conscious, brain.