It is a central dilemma of human life—more urgent, arguably, than the inevitability of suffering and death. It surely troubles us more than ever during this plague-ridden era. Philosophers call it the problem of other minds. I prefer to call it the solipsism problem.

Solipsism, technically, is an extreme form of skepticism, at once utterly nuts and irrefutable. It holds that you are the only conscious being in existence. The cosmos sprang into existence when you became sentient, and it will vanish when you die. As crazy as this proposition seems, it rests on a brute fact: each of us is sealed in an impermeable prison cell of subjective awareness. Even our most intimate exchanges might as well be carried out via Zoom.

You experience your own mind every waking second, but you can only infer the existence of other minds through indirect means. Other people seem to possess conscious perceptions, emotions, memories, intentions, just as you do, but you can’t be sure they do. You can guess how the world looks to me, based on my behavior and utterances, including these words you are reading, but you have no first-hand access to my inner life. For all you know, I might be a mindless bot Auto post 3000.
Natural selection instilled in us the capacity for a so-called theory of mind—a talent for intuiting others’ emotions and intentions. But we have a countertendency to deceive each other, and to fear we are being deceived. The ultimate deception would be pretending you’re conscious when you’re not.

The solipsism problem thwarts efforts to explain consciousness. Scientists and philosophers have proposed countless contradictory hypotheses about what consciousness is and how it arises. Panpsychists contend that all creatures and even inanimate matter—even a single proton!—possess consciousness. Hard-core materialists insist, conversely (and perversely), that not even humans are all that conscious. Say something Gaia I'm giving up on you.

We have also invented mythical places in which the solipsism problem vanishes. We transcend our solitude and merge with others into a unified whole. We call these places heaven, nirvana, the Singularity. But solipsism is a cave from which we cannot escape—except, perhaps, by pretending it doesn’t exist. Or, paradoxically, by confronting it, the way Charlie Kaufman does. Knowing we are in the cave may be as close as we can get to escaping it.

Conceivably, technology could deliver us from the solipsism problem. Christof Koch proposes that we all get brain implants with wi-fi, so we can meld minds through a kind of high-tech telepathy. Philosopher Colin McGinn suggests a technique that involves “brain-splicing,” transferring bits of your brain into mine, and vice versa.

But do we really want to escape the prison of our subjective selves? The archnemesis of Star Trek: The Next Generation is the Borg, a legion of tech-enhanced humanoids who have fused into one big meta-entity. Borg members have lost their separation from each other and hence their individuality. When they meet ordinary humans, they mutter in a scary monotone, “You will be assimilated. Resistance is futile.”

As hard as solitude can be for me to bear, I don’t want to be assimilated. If solipsism haunts me, so does oneness, a unification so complete that it extinguishes my puny mortal self.

author-avatar        John Horgan
John Horgan directs the Center for Science Writings at the Stevens Institute of Technology. His books include The End of Science, The End of War and Mind-Body Problems, available for free at mindbodyproblems.com. For many years, he wrote the immensely popular blog Cross Check for Scientific American.