Right now, you're reading these words. You assume I exist—that someone wrote them, that there's a world beyond your screen filled with billions of other minds. But here's a thought experiment that's troubled philosophers for centuries: what if none of that is true?

Solipsism is the philosophical position that only your mind definitely exists. Everything else—other people, the physical world, even your own body—might be nothing more than elaborate projections of your consciousness. It sounds absurd. It probably is absurd. But here's the unsettling part: you can't prove it wrong.

Think about what you actually know with absolute certainty. You know you're having experiences right now. You know thoughts are happening. Descartes landed on this bedrock truth: cogito ergo sum—I think, therefore I am. But notice what's missing from that certainty. It doesn't include anyone else.

When you talk to a friend, you experience seeing their face, hearing their voice, feeling their presence. But all of that is happening inside your consciousness. You never step outside your own mind to verify that your friend has their own inner experience. You assume they do because they act like you, but a very sophisticated puppet could do the same.

This isn't just wordplay. Every single piece of evidence you have for other minds comes to you through your own perceptions, which are themselves mental events. You're trying to prove something exists outside consciousness using only tools that exist inside consciousness. It's like trying to determine if you're dreaming—while still in the dream.

Takeaway

The only existence you can be absolutely certain of is your own consciousness—everything else is inference, however reasonable that inference might be.

Last night you probably dreamed. In that dream, there were objects, maybe people, perhaps entire landscapes. They felt real at the time. You didn't think, mid-dream, "Ah yes, this is clearly a fabrication of my sleeping brain." The dream presented itself as reality, and you bought it completely.

Now, what's the test that distinguishes your waking life from an incredibly detailed, internally consistent dream? You might say waking life is more vivid, more continuous, more logical. But dreams can be vivid. And you've forgotten most of your dreams, so how would you know if they were continuous? As for logic—dreams often feel logical until you wake up.

The philosopher Zhuangzi famously wondered if he was a man who dreamed he was a butterfly, or a butterfly dreaming he was a man. This isn't poetry—it's pointing at a real epistemological gap. You have no dream-proof test for waking life. The best you can say is that this reality is much more stable and detailed than any dream you remember. But that's not the same as proving it's fundamentally different.

Takeaway

The line between "real" and "elaborate mental construction" may be blurrier than we'd like—stability and detail don't prove external existence.

Here's where philosophy gets practical. Let's say you can't disprove solipsism. Does that mean you should live as if you're the only conscious being? That everyone around you might be philosophical zombies—bodies without inner experience—or projections of your mind?

Consider two scenarios. In the first, solipsism is true, and you've spent your life being kind to beings that don't actually experience anything. In the second, solipsism is false, and you've spent your life treating real conscious beings like they don't matter. The downside of being wrong in scenario two is catastrophic. The downside of being wrong in scenario one is basically zero.

This is a kind of moral Pascal's Wager. Even if you can't resolve the metaphysical question, the ethical response is clear. Treat other apparent minds as real minds. Not because you've proven they exist, but because the cost of being wrong the other way is unconscionable—and because, frankly, solipsism makes for a lonely and impoverished way to live.

Takeaway

Philosophical certainty isn't required for ethical action—when stakes are asymmetrical, treat uncertain minds as if they matter.

Solipsism probably isn't true. The world's stubborn consistency, its resistance to your wishes, its endless capacity to surprise you—all of this suggests something beyond your mind is doing the heavy lifting. But probably isn't the same as certainly.

Perhaps the creepiest thing about solipsism isn't the possibility that you're alone. It's the reminder that your entire picture of reality is built on foundations you can't inspect—and that you've been trusting those foundations your whole life without ever checking the receipts.