The philosophical view known as panpsychism has ancient roots, with its earliest adherents being pre-Socratic thinkers. Simply stated, it is the notion that all matter and energy is sentient. The idea can also be found in the works of Aristotle (“soul is mingled with everything in the whole universe”) and Plato (“this world is a living body endowed with a soul”). The theory saw a revival in the Renaissance: Philosophers Baruch Spinoza and Gottfried Wilhelm Leibniz advocated variations of it. “All things are animate in various degrees,” Spinoza wrote in his Ethics.

Now, some might argue that this sounds like hippie nonsense. A word of caution, then, before we go any further: Panpsychist claims such as these should not be interpreted over-literally.

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One of the most enduring conflicts in philosophy concerns the so-called “mind-body problem,” the relationship between mind or consciousness (not obviously physical) and brain or body (physical, obviously). Battle lines have been drawn, and thinkers have, for the most part, split themselves into two camps: On the one hand, there are physicalists or materialists, who say, essentially, that states of mind can be reduced to states of the brain. And on the other hand, there are dualists or Cartesians (after French philosopher René Descartes), who say, essentially, that mind lives in a world of its own, that consciousness exists over and above physical matter—a kind of ghost in the machine. The battle between these two factions has raged for centuries, with no peace treaty in sight.

But panpsychism offers a scandalous third possibility. As Seattle University’s Daniel Dombrowski writes, panpsychism rejects the dilemma; instead, it “suggests that every instance of reality is mind-like or at least exhibits some slight ability to feel the difference between itself and the rest of what is” (emphasis supplied).

In (what has become) the standard Western worldview, an extraordinary claim like this one would seem to require some extraordinary evidence. And panpsychists, for the most part, do not—and, maybe, cannot?—offer any. Perhaps the most famous modern panpsychist, 20th-century philosopher Charles Hartshorne, preferred to argue for panpsychism by extended analogy: If we can imagine a human mind as conscious, why not a dog’s? If a dog’s, why not an insect’s? If an insect’s, why not an amoeba’s? Why not the individual cells that compose the brain? Why not the atoms that make up those cells? “We in our human way,” Hartshorne wrote, “share in the subhuman emotional life of cells; they in their subhuman way share in our emotional life. Because cells are limited creatures, compared to us, the vagueness … must be much more extreme in the cell’s sense of our feelings.” Like, wow, that’s trippy, man.

If you ask contemporary panpsychists, however, they’ll say that their philosophy’s scope is much broader than modern scientific materialism’s. (In other words, “there are more things in heaven and earth, Horatio…”.) And, they’ll add, panpsychism is perfectly capable of accounting for science’s appeal as a method of reasoning. As Dombrowski wrote: “We should all be materialists if what is meant by ‘materialism’ is that human beings and everything else are made up of smaller integrated unities”—i.e., cells, molecules, atoms, protons, quarks, etc., things that can be studied scientifically. He continues: “But this is not what is usually meant by the term; it usually means belief in inert lifeless stuff as the building blocks of the world. It is only a short step from this belief to the widely shared view that nature is ‘mere resource’ for human exploitation.” And indeed, some environmental ethicists, such as ecofeminist Val Plumwood, have taken up the panpsychist cause (though not without criticism).

In other words, what justifies the assumption—and it is, in an ultimate sense, merely an assumption—that all matter and energy is not alive? Isn’t it true that subatomic particles move in spooky ways via quantum entanglement—as though serving some higher will, perhaps? And isn’t it true that all living things—and even nonliving things like electrons—respond to changes in their environments (broadly conceived)? There is in all matter an animate or vibrant quality, even if we can discern no obvious message in the vibrations.

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Two virtues are usually claimed for panpsychism—namely, that it elegantly resolves two of the deepest mysteries in the universe.

1. It explains how life can result from nonliving matter.
2. It explains how consciousness can result from nonconscious matter.

It solves these problems simply—by denying that they exist. Since all matter and energy is, to varying degrees, sentient, there’s really no such thing as “nonliving” or “nonconscious” matter, only matter whose potential to participate in these “higher” states has not been realized. In other words, animals, cells, and even inanimate objects have in them some innate potential to participate in higher states of consciousness, including rationality. As the poet William Wordsworth said of birds in his “Lines Written in Early Spring”:

Their thoughts I cannot measure:—

But the least motion which they made

It seemed a thrill of pleasure.

Not everyone agrees, of course, that the theory is actually capable of doing everything that’s claimed for it. Positivist philosopher Karl Popper, for example, argued in 1977 that panpsychism doesn’t really resolve these mysteries at all. There is still, he notes, a massive leap forward from nonliving to living, and yet another from nonconscious to conscious. Panpsychism doesn’t even try to explain how these happen. What’s more, Popper argues, the fact that humans can put unconscious water molecules to use in our body’s conscious systems doesn’t automatically mean that water contains some sort of “proto-conscious” potential. Finally, Popper argues, science has shown that atoms have no memory, a minimum of which would seem to be required for their having even proto-consciousness. This last argument, however—like so many philosophical claims tethered to the science of their day and age—proved overconfident: It turns out that Bose-Einstein condensates can retain “memory.”

Despite Popper’s criticisms, panpsychism’s proponents have gradually worked their way back into the philosophical mainstream. Most notably, philosopher David Chalmers began suggesting, in the late 1990s, that the mere existence of the panpsychist theory has important logical consequences for how we understand scientific materialism. And, in his 2013 Amherst Lecture in Philosophy (as well as an entertaining series of YouTube videos), Chalmers joined others who began directly arguing in favor of panpsychism.

Even if panpsychism sounds zany, its revival may benefit both philosophy and science. It is, at the very least, an intriguing hypothesis, and one that is not so easily refuted. Popper’s criticisms mostly read like the work of someone determined to reverse-engineer an argument against a view that he—an ardent devotee of a particularly hard-nosed brand of philosophy of science—instinctively disliked. That panpsychism, similar to science itself, doesn’t explain everything—like how species evolve—is obvious. As is the fact that it isn’t the only possible explanation for the link between mind and brain. But are these really adequate reasons to dismiss out of hand one of the most intriguing alternatives to the standard Western conception of the mind? Should we so hastily push aside a view that attracted even Plato and Aristotle? One wants to suggest that Popper “open the doors.”

Perhaps the biggest strike against panpsychism, then, is simply that it seems “far out”—loopy and spiritual—in an era when the dominant culture is fixated on the ideas of scientific accuracy, logical rigor, and quantitative precision. It dares, in other words, to speak about the fundamental nature of the world in an imprecise and metaphorical style. Panpsychists speak of matter having “feelings,” of “the will,” of “Nature, which is the same as God,” of a “world soul.” These are phrases our discourse has all but banished to the broom cupboard, along with alchemy, astrology, hex-craft, and magic.

But what’s baffling about this situation is the short-sightedness about scientific progress—about the incredible frontiers of the unknown—that it reflects. It’s as though 2015—an arbitrary time at an arbitrary point in an unimaginably vast and complex space-time continuum—were the moment of knowledge and certainty. Why not risk expanding our minds? If panpsychism is true, and if, as postulated by some contemporary physicists, the cosmos is expanding, might we not think of the universe as literally a mind expanding, a world soul growing up?

As Hartshorne, at the age of 80, wrote—barring further discoveries—the virtue of panpsychism for our age (probably) won’t lie in its ability to generate new insights or technologies. Rather, the trippy possibility of a world soul bears on a wide variety of “strictly philosophical, religious, aesthetic, and ethical issues.” And these, it seems clear, have not become less pressing.