What’s at the bottom of things? If we keep asking "Why?" where do we end up? The monotheistic faiths assert that our questions must culminate in God, a solitary, supernatural creator. Dissatisfied with that hypothesis, physicists postulate that everything stems from a single primordial force or particle, perhaps a supersymmetric string, from which flow the myriad forces and particles of our fallen world.

Notice that, for all their differences, religion and physics share the ultrareductionist conviction that reality comes down to one thing. Call this the oneness doctrine. For the past 40 years, I’ve harbored a not-entirely-rational aversion to the oneness doctrine, for reasons that I’ll disclose below. So, I’m intrigued by the conjecture that at the heart of reality there are at least two things doing something to each other. In other words, there is an interaction, a relationship. Call this the relationship doctrine.

The wildly inventive physicist John Wheeler was an early explorer of this notion. In a 1989 paper, "Information, Physics, Quantum: The Search for Links," Wheeler takes a stab at "the age-old question: How come existence?" The answer, he speculates, might come from a fusion of physics and information theory. The former traffics in "its," or physical things, and the latter in "bits," defined as answers to yes-or-no questions.

Wheeler proposes that "every physical quantity, every it, derives its ultimate significance from bits, binary yes-or-no indications, a conclusion which we epitomize in the phrase, it from bit." Noting the crucial role of measurement in the outcome of quantum experiments, Wheeler suggests that we live in a "participatory universe," in which we bring the world into existence, and vice versa.

Picking up on Wheeler’s ideas, physicist Carlo Rovelli argues in a 1996 paper, "Relational Quantum Mechanics," that quantum mechanics undermines "naive realism," the notion that science discovers a reality that exists independently of our observation of it. He proposes what he calls a "relational" interpretation of quantum mechanics, which says things only exist in relation to other things. Rovelli notes that Galileo and Kant, among others, anticipated the relational perspective.

Rovelli has continued expounding the relationship doctrine. In a volume of essays on panpsychism to be published in the Journal of Consciousness Studies, he writes: "20th-Century physics is not about how individual entities are by themselves. It is about how entities manifest themselves to one another. It is about relations." Rovelli suggests that this perspective applies not merely to electrons and photons but to all of reality, whether material or mental. "I see no reason to believe that this should not be sufficient to account for stones, thunderstorms and thoughts."

Neither Wheeler nor Rovelli cites Douglas Hofstadter in their early papers, but they might have. In his sui generis 1979 work Gödel, Escher, Bach, Hofstadter plunges into the deepest mysteries of mind and matter. Like Wheeler and Rovelli, Hofstadter, who studied physics, asserts that particles only acquire properties through interactions with other particles. But as his book’s title suggests, Hofstadter goes far beyond physics in his effort to explain the world, drawing upon mathematics, computer science, genetics, music and art.

Hofstadter is obsessed, I’d say it’s fair to say, with things that refer to, talk about or otherwise interact with themselves—notably Gödel’s incompleteness theorem, a proof about the limits of proofs. Hofstadter proposes that consciousness, the self, life, existence as a whole, stem from "strange loops," things that bring themselves into existence. The artist M.C. Escher provides a striking image of a strange loop in his famous drawing of two hands drawing each other.

Another eloquent explicator of the relationship doctrine is science writer Amanda Gefter. After hearing her give a talk last December, I interviewed Gefter for my podcast "Mind-Body Problems." Gefter seems intent on moving past old dualities, like the one between mind and matter. She is dissatisfied with both strict materialism, which decrees that matter is fundamental, and idealism, which insists that mind precedes matter. "The central lesson of quantum mechanics," Gefter told me, "is that "subject and object can never be decoupled."

Gefter has drawn inspiration from diverse sources, including Wheeler and philosopher Martin Buber, author of the classic work I and Thou. She is also intrigued by QBism, sometimes called quantum Bayesianism, an interpretation of quantum mechanics that overlaps with those of Wheeler and Rovelli. According to QBism, each of us creates our own, personal, world through our interactions with it; objective, consensual reality emerges from the interactions of all our subjective worlds.

Maybe, Gefter speculates, we don’t live in either a first-person world or a third-person world, as implied by idealism and materialism, respectively. Maybe we live in a second-person world, and the fundamental entity of existence is not "I" or "It" but "You." "The second person always deals in relations," Gefter explains, because every "You" implies an "I" interacting with the "You." This view "is definitely not materialism," Gefter says, "but it’s not idealism either."

Part of me finds the relationship doctrine, and especially Gefter’s you-centered metaphysics, beautiful and consoling, a welcome alternative to mindless materialism. The relationship doctrine also seems intuitively sensible. Just as words must be defined by other words, so we humans are defined, and to a certain extent brought into existence, by other human beings. How could it be otherwise?

Moreover, as I mentioned above, I have a long-standing aversion to the oneness doctrine. This antipathy dates back to a drug trip in 1981, during which I felt myself becoming a solitary consciousness, the only one in the universe. Nothing existed except for me. At first, this revelation thrilled me, but then it freaked me out. I felt excruciatingly, terrifyingly alone. This emotion was accompanied by a weird intellectual subtext. I thought: What is the difference between one thing and nothing? One thing only exists in relation to something else. If I am the only thing that exists, I might as well not exist.

What had been a very good trip became a very bad one, and the negative aftereffects lingered; solipsism wasn’t just an amusing fancy any more but a terrifying possibility. Since then, I’ve looked askance at the oneness doctrine, whether it comes from mysticism or science. I fear the oneness doctrine is true—that a single mind underlies everything—but I don’t want it to be true. Hence my attraction to the relationship doctrine.

And yet I have doubts about the relationship doctrine, as I do about all metaphysical systems that privilege mind, consciousness, observation, information. They smack of narcissism, anthropomorphism and wishful thinking. That’s why I have derided mindcentric theories as neogeocentrism, throwbacks to the medieval belief that the universe revolves around us. The relationship doctrine, in particular, reminds me a bit too much of the sentimental slogan "God is love."

To be honest, I’m suspicious of all ultimate theories, whether based on oneness, relationships, strange loops or some other principle. John Wheeler ends his 1989 essay on the it from bit with an uplifting exclamation, almost a prayer. "Surely someday, we can believe, we will grasp the central idea of it all as so simple, so beautiful, so compelling that we will all say to each other, ‘Oh, how could it have been otherwise! How could we all have been so blind so long!’"

I once shared Wheeler’s yearning for a revelation so powerful that it would dispel the weirdness of existence. Now I fear such an epiphany. If we become convinced that we have figured things out, our creative endeavors—whether scientific, artistic, spiritual or political—might ossify. Fortunately, I have faith in humanity’s curiosity and restlessness. My hope, and expectation, is that the world will keep us guessing forever.

Further Reading:

I delve into all sorts of knotty relationship issues in my two most recent books: Pay Attention: Sex, Death, and Science, and Mind-Body Problems: Science, Subjectivity and Who We Really Are.

See also my podcast "Mind-Body Problems," where I talk to Amanda Gefter and other experts obsessed with mysteries of existence.

This is an opinion and analysis article; the views expressed by the author or authors are not necessarily those of Scientific American.