Here's a different approach. Don't ask what you can doubt. Ask what you've tested. Not intellectually. Physically. Metabolically. With hours and failure and adjustment. You think you know how to build muscle. Have you gained twenty pounds of it? You think you understand sleep

Descartes attempted this excavation. Strip away everything that could possibly be doubted. Senses? They deceive. Mathematics? Perhaps a demon manipulates your reasoning. Strip, strip, strip—until you reach bedrock. Cogito ergo sum. I think, therefore I am. Descartes' solution was God. A perfect being wouldn't deceive us,

There is a question that returns, no matter how many times you think you've answered it: What do you actually know? Not what you've read. Not what sounds convincing when you repeat it. What you know—tested, earned, verified against the world's resistance. Most