What’s going on in your head right now? How about ... now? Or ... now? Answering this question is harder than you might think. As soon as you pay attention to your thoughts, you alter them, as surely as you alter an electron’s course by looking at it. You can’t describe your thoughts the way you describe, say, the room in which you are reading, which remains stolidly unaffected by your scrutiny.

William James draws attention to this paradox in “The Stream of Thought,” a section of The Principles of Psychology. Trying to examine your thoughts through “introspective analysis,” he writes, is like studying snowflakes by catching them in your “warm hand,” “seizing a spinning top to catch its motion” or “trying to turn up the gas quickly enough to see how the darkness looks.”

I’ve been brooding over these sorts of puzzles a lot lately, even more than usual. In 2020 I released a book entitled Pay Attention: Sex, Death, and Science, a stream-of-thought account of a day in my life. Or rather, in the life of my fictional alter ego, Eamon Toole, a “divorced science writer and professor struggling to remain rational while buffeted by fears and desires.” As soon as I send a book out into the world, I compulsively think of things I should have put in it.

Also, my ongoing attempt to learn quantum mechanics has mystified my world, inner and outer. So, I’d like to offer a few thoughts (second thoughts? afterthoughts?) about thoughts, the most inescapable and maddeningly elusive features of our existence.

Meta-Thoughts and Thoughtless Thoughts

A note on terms. James coined the phrases “stream of thought” and “stream of consciousness” and sometimes used them interchangeably, but I distinguish thoughts from consciousness in the following way: Thoughts are the contents of consciousness, including fears, fantasies, recollections, realizations, deliberations, decisions and all the other flora of subjective experience. If consciousness is the medium, thoughts are the message.

I also like the easy self-referentiality of “thoughts about thoughts,” which captures a deep truth about us. We are what Douglas Hofstadter calls self-generating “strange loops,” akin to M. C. Escher’s famous drawing of two hands drawing each other. (Who draws the drawer?) Thoughts spring from thoughts and—in ways still beyond our ken—from our brains, which contain roughly 100 billion neurons linked by one quadrillion synapses, each of which processes an average of 10 electrochemical signals, or action potentials, every second.

If you equate action potentials with the operations of a computer, as many neuroscientists do, then the brain carries out 10 quadrillion operations in a typical second. That approaches the speed of the world’s fastest supercomputers, and the brain may perform exponentially more calculations via processes other than action potentials. The result of all this activity is that brains churn out thoughts as ceaselessly as hearts pump blood.

As James puts it, thoughts are “continuous,” they “flow,” they keep coming even when we pay no attention to them, and they keep changing; no thought is precisely like another. James thus doubts whether psychologists can reduce the human mind to a mental equivalent of atoms as physicists have done with matter.

With some effort, I can direct my thoughts, focus them, but they often seem to have a will of their own. They swerve this way or that for reasons obscure to me, a tendency that Buddhists disparage as “monkey mind.” When we do notice a thought and reflect on it—perhaps to convey it to ourselves or to others—we instantly transform it, turning it into a different, higher-order thought. Call it a meta-thought, a thought about a thought.

Meta-thoughts—the thoughts I express to myself and to others through writing and speech—are my bread and butter. I make my living off them. But they constitute an infinitesimal fraction of my thoughts. The vast majority are unformed, incoherent, inexpressible, and they come and go without my dwelling on them. You might call them thoughtless thoughts. Thoughtless thoughts are what course through your head when no one is watching you, not even you.

Consciousness Without Thought?

I once tried to teach meditation to a class of stressed-out freshmen. I told them to close their eyes, still their minds and stop thinking. After 10 minutes of silence, I asked how many had succeeded in thinking of nothing. To my surprise, about half raised their hands. I didn’t believe them. Even freshmen always have thoughts, whether or not they notice them.

Is thoughtless consciousness possible? Yes, according to religious scholar Robert Forman, a veteran meditator. He claims that he and others have achieved “pure consciousness,” a mystical state devoid of any specific thoughts. You are conscious but not conscious of anything. Consciousness without content strikes me as a contradiction, an oxymoron, like a book without words or a film without images. And how would you know you’re in a state of pure consciousness? How would you remember it? Even Forman admits that states of pure consciousness, if they exist, are rare.

Meditation is touted as a route to knowledge of your deepest self, your innermost thoughts. I’ve had delightful experiences meditating, especially on a silent retreat in 2018. But meditation and other contemplative techniques are designed to control and suppress thoughts rather than to understand them. Meditation is self-brainwashing aimed at taming your monkey mind. I don’t want to tame my monkey mind; I want to study it, to comprehend its antics.

Although we may not notice them and may even deny their existence, thoughtless thoughts are always there, underpinned by our brains’ incessant chatter. Without thoughtless thoughts, we would lack meta-thoughts. Thoughtless thoughts are the dark matter of our minds, giving shape via hidden mechanisms to what is observable, visible, luminous in our inner cosmos.

The Limits of Stream-Of-Thought Fiction

Can we study thoughtless thoughts, the mind’s dark matter, given that simple introspection doesn’t work? Some neuroscientists predict that external brain-scanning devices, such as MRIs, or arrays of implanted electrodes will soon allow us to read minds. But this feat would require cracking the neural code, the set of rules or algorithms that turn neural activity into mental activity—that is, thoughts. The neural code is the enigma at the core of the mind-body problem. The more we investigate it, the more intractable it seems.

I try to describe my thoughts in my book Pay Attention (original title: What Is It Like to Be a Science Writer?). The book is based on journals in which I wrote down what I did, saw, said, heard and thought over the course of a typical day, as I commuted to the university where I work, talked to a freshman humanities class (about James’s “Stream of Thought”), jawed with colleagues over lunch (about Thomas Kuhn’s views of “truth”) and spent the evening with “Emily,” my girlfriend.

In the first draft of my book, to make my thoughts seem more raw and real, I expressed them as sentence fragments running into each other, with little punctuation. An editor who read this draft described it as “sludge.” Even I found that draft hard to read. So I cheated. I rewrote the book with more or less coherent sentences with conventional grammar and punctuation. I also added contextual information for readers, information that I wouldn’t have actually thought about because I just knew it implicitly.

To justify these moves in the direction of readability, I could point out that the book’s narrator is an extremely self-conscious science writer trying to make his private thoughts public. He is in a sense performing his thoughts, first for himself and then for readers. But that means my book consists of meta-thoughts. It isn’t an accurate depiction of my thoughtless thoughts, which remain veiled from me.

Nobody depicts thoughts in all their raw weirdness as vividly as James Joyce. In Ulysses, Joyce plops us inside the heads of Stephen Dedalus, a teacher and aspiring writer and an avatar for Joyce as a young man; Leopold Bloom, a nerdy, genial ad salesman; Bloom’s voluptuous wife, Molly; and other characters living in Dublin in the early 20th century. We see, feel, remember what they see, feel, remember.

But Joyce’s notoriously difficult masterpiece isn’t entirely stream of thought. If it were, it would be far more difficult. To help orient us, give us a little context, Joyce occasionally shifts his point of view from inside characters’ heads to outside, that is, from a first-person to a third-person perspective.

Joyce’s final opus, Finnegans Wake, which I “read” in college, makes no concessions to readability. Even Joyce’s admirers complained about its opacity, but James defended his gobbledygookian work. “One great part of every human existence,” he told a friend, “is passed in a state which cannot be rendered sensible by the use of wideawake language, cutanddry grammar and goahead plot.” But even Finnegans Wake, an unrivaled imagining of mental dark matter, consists entirely of Joyce’s hyperconscious, insanely erudite meta-thoughts. And what about all the thoughts that cannot be captured by words?

Hidden-Variable Theories of the Mind

A final point: I see analogies between efforts to understand thoughts and the quantum realm. I alluded to one correlation above: observing particles alters them, as does observing thoughts. Here’s another: some physicists, dissatisfied with probabilistic quantum accounts of electrons and photons, seek to explain their behavior in terms of “hidden variables” that follow deterministic rules.

Mind scientists, similarly, have proposed hidden-variable paradigms of the mind. Psychoanalysis holds that our conscious minds are yanked this way and that by deep-rooted lusts and aversions. Evolutionary psychology traces our emotions and actions to instincts embedded in our ancestors by natural selection. Cognitive science postulates that our thoughts stem from computations carried out by our neural machinery and are as far removed from our conscious thoughts as the machine code of your smartphone is from the icons on its screen.

Although each of these paradigms has appealing features, each finally falls short, as do all theories of the mind. Will science ever discover a final theory of the mind? One that solves the mind-body problem and makes us fully transparent to ourselves? That reveals the hidden variables underpinning and linking our meta-thoughts and thoughtless thoughts?

I doubt it. Physicists can’t grok the behavior of a single electron that is identical to every other electron. So what hope do we have of capturing the thought passing through your head right ... now, a thought unlike any that you, let alone anyone else, have ever had or will have? And if we can’t grasp a single thought, which melts the instant we grasp it, how can we possibly understand ourselves? Think about that.