In 1974, philosopher Thomas Nagel published an essay with a title that sounds like it belongs to a children’s book: What Is It Like to Be a Bat? But behind this seemingly playful question lies one of the most profound philosophical challenges of the modern age: the mystery of consciousness. Specifically, whether we can ever understand what it feels like to be something—or someone—else.

Nagel wasn’t interested in bats because they’re spooky or exotic. He chose bats precisely because they are close enough to us to share some fundamental traits (they’re mammals, after all), yet different enough that we can’t easily project ourselves into their experience. They see the world not through sight in the way we do, but through echolocation—mapping their surroundings with sound. It’s so foreign to our own sensory experience that imagining what that feels like is nearly impossible.

And that’s the point.

Nagel’s argument is deceptively simple but revolutionary: even if we knew everything there is to know about how a bat’s brain works—if we could trace every neural firing, decode every echo-response, map its entire sensory and motor system—we still wouldn’t know what it is like to be a bat. We’d have knowledge, yes. But we’d still be missing the experience.

This inner experience, Nagel argues, is subjective. It is what philosophers now call qualia: the felt qualities of perception, like the redness of red or the pang of nostalgia. These are things we can describe or even measure in terms of brain activity, but we can’t actually share them in any direct way. Consciousness, then, is not something that can be entirely captured from the outside.

Science, for all its triumphs, is built on objectivity. It operates on what can be observed, quantified, and explained. But consciousness doesn’t present itself that way. It’s not something you look at—it’s something you are. You don’t just observe consciousness; you live it.

This creates what Nagel calls the “explanatory gap”—the chasm between what science can say about brain processes and what it feels like to be a conscious being. We can measure the neural firings that happen when you fall in love, but no equation can convey the aching wonder or vulnerability of that moment. Similarly, we could record every detail of a bat’s life, but we’d still be shut out of the strange, echoic world it inhabits.

And so, Nagel’s bat becomes a symbol of humility in the face of mystery. His essay doesn’t dismiss science or claim that consciousness is some magical essence beyond understanding. Rather, he points out that our current tools may not be sufficient. To explain what consciousness is, we might need a new kind of science—one that can integrate both the objective and the subjective, the third-person view and the first-person feel.

This has vast implications. It challenges the idea that the mind can be fully reduced to the brain, or that artificial intelligence—no matter how advanced—can be conscious just by simulating neural networks. Could an AI feel anything? Could it ever know what it’s like to be something? Or is it just processing information with no inner world at all?

Nagel’s essay remains a cornerstone of debates in both philosophy and neuroscience because it forces us to confront the limits of knowledge. It’s not that we know too little—it’s that there may be something we can’t know, at least not through observation alone. The mystery of consciousness isn’t about gaps in data; it’s about a fundamental difference between knowing about something and knowing what it’s like.

So, what is it like to be a bat?

We don’t know. And maybe we never will. But Nagel’s point is not to despair over what we can’t grasp. It’s to remind us that consciousness—our own and others’—isn’t just a riddle to be solved. It’s a reality to be respected. We live it every day, and yet we barely understand it.

In the end, the bat is not just a symbol of other minds—it’s a mirror for our own. When we ask what it’s like to be a bat, we’re also asking what it’s like to be us—to be conscious, alive, and always just beyond the reach of full understanding.

Credits: Inspired by Thomas Nagel’s essay What Is It Like to Be a Bat? (1974).