Michael Pollan's new book explores consciousness through sentience, feeling, thought, and selfhood.

The new book offers an overview of current consciousness science.

The book’s central achievement is revealing how many questions remain open.

Michael Pollan's widely anticipated new book, A World Appears: A Journey into Consciousness, brings his signature acumen and wit to one of science's essential mysteries.

Along the way, he pursues numerous related questions: Are plants conscious? Are AIs sentient? How does the brain generate the stream of thought – and can we quiet it? Is the self a fiction?

Although Pollan doesn't claim to answer these questions definitively, A World Appears is a delightful, deeply informed, and thought-provoking tour through the central mystery of what it means to be human.

Pollan begins by identifying the “hard problem” of consciousness: Why aren’t we all mindless machines? Why can’t the complicated neural processing in our brains guide our behavior without this accompanying halo of awareness?

We want to believe science can unlock all mysteries of the universe, but consciousness challenges that belief. Asking why consciousness exists is a bit like asking why anything exists rather than nothing at all. It’s quite possibly a question that science isn’t designed to answer.

He also notes that, in trying to answer the question of consciousness, we may have to reject core assumptions about the nature of reality. For example, we might ultimately embrace idealism: the notion that reality is composed of ideas.

After surveying leading theories, he chooses to explore four aspects of consciousness: sentience, feeling, thought, and selfhood.

Are plants conscious?

Chapter 1 turns to the question of plant consciousness – a suitable starting point for someone who’s famously written about plants. One of the most striking findings Pollan highlights is that when people are on psychedelic drugs, they are about twice as likely to attribute consciousness to plants.

That prompts a question: Does this happen because psychedelics reduce us to a kind of magical thinking we’re better off without? Or is it because psychedelics offer an insight into reality that we’ve learned to ignore?

We also meet a group of maverick scientists known as the “plant neurobiologists,” who analyze whether plants are conscious and have drawn attention to their extraordinary cognitive abilities, such as the Mimosa’s ability to learn from experience.

Finally, he asks: Why the species chauvinism about consciousness? Why do we tend to think that only the so-called “higher animals” – creatures with nervous systems like our own – can be aware of the world?

Pollan then turns to feelings – love, joy, despair, fear, envy. Are feelings the crucial link between consciousness and the body? One might think that the absence of feeling is precisely what distinguishes AIs from humans. Without feelings, AIs remain mindless machines.

But that prospect raises a question: Could we ever build an AI that feels? And if so, what would the ethical implications be?

The chapter concludes with what Pollan humorously calls his “rickety defense of biological consciousness.” The idea that AIs are conscious and feeling – rather than mindlessly simulating conversation – came to the fore with the case of Blake Lemoine, who was fired from Google for releasing data suggesting that LaMDA was sentient. Yet a growing number of AI theorists think sentient AI is a plausible future.

Pollan’s own skepticism comes from the faulty brain-as-computer metaphor that’s prominent in these conversations. Yet the chapter made me wonder about the ethical implications of denying the possibility of AI sentience. After all, ethical progress quite often consists of “expanding the moral circle” to embrace an increasingly wider sphere: people in distant places, animals, even ecosystems. It seems hard to justify the view that we should place a decisive limit on this widening circle.

The stream of consciousness

Theorists of consciousness generally focus on sensation – what it's like to, say, experience the color red. Yet what we call the stream of consciousness offers a much richer and more complex blend of ingredients: thoughts, forgettings, urges, half-formed intentions, half-remembered faces. It's like a sludge that accompanies every waking moment.

One problem with understanding thought is that it seems nearly impossible both to think and observe yourself thinking at the same time. For guidance, he turns not only to cognitive scientists like Russell Hurlbert, but novelists like James Joyce, Virginia Woolf, and Lucy Ellmann, whose book Ducks, Newburyport is a single sentence that runs over 1,000 pages.

Pollan also shares his frustrating and, at times, tense conversations with Hurlburt, a scientist who’s devoted his career to identifying the precise elements of the stream of consciousness. At times, Hurlburt seemed to suggest that Pollan was not very good at separating the exact elements of the stream of consciousness from his own assumptions and misrememberings.

One philosopher who could have come to Pollan’s aid is Daniel Dennett, who argues in his remarkable Consciousness Explained (1991) that there’s no special place in the brain where unconscious perceptions suddenly become conscious. Along with that, he urges that one cannot identify, precisely, which bits of information circulating in the brain “did” or “didn’t” become conscious. The field of awareness is more porous and subject to interpretation.

Is the self a fiction?

When Pollan turns to the self – the experience one has of being a person with a stable set of values and goals — he begins with the eighteenth-century Scottish philosopher David Hume, who (along with numerous Buddhist thinkers) was skeptical that the self exists.

From Hume, Pollan wonders if the self is a fiction generated by the brain, designed to facilitate a sense of narrative continuity. If I didn't think the “self” I am now and the “self” I will be a year from now are the same self, why would I act for the sake of my future?

A short epilogue poses the question of whether we should not merely theorize about consciousness, but experience it more directly through meditation. At the bidding of a Zen priest, he spent nearly a week alone in a (sparsely furnished) cave. With the clamor of the outside world quieted, he returned to a more rudimentary form of consciousness, one prior to thought or selfhood – perhaps closer to plant consciousness. He closes by wondering if consciousness is less “a scientific or philosophical puzzle to be solved and more…a practice, a way to once again be altogether here.”

Pollan’s book doesn't answer fundamental questions about consciousness, yet it marks a greater achievement: It confronts us with how strange, wondrous, and even miraculous consciousness is. Along the journey, the reader encounters a wealth of scientific ideas about plant consciousness, emotions, the stream of thought, the nature of self, and the possibility of AI sentience. It's a journey well worth taking.

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