What if everything we know is fundamentally uncertain?

I used to think finding truth was simple: do research, make observations, think carefully, and the truth would be revealed. After all, that's how it worked in school, where the facts always seemed obvious and clear.

Then I got into the real world, working at startups by day and researching AI by night, and was surprised to learn that finding truth is anything but simple.

We reckon truth by combining evidence with logic, which should be a straightforward process. But all logic, no matter how solid, depends on assumptions that cannot themselves be proven true. This makes truth tricky to nail down.

In particular, we must assume that the rules of logic, and all methods for knowing truth, are themselves true. We have to assume them because otherwise we’d need to prove their truth using the very same rules and methods we’re trying to prove, setting up an infinite loop of unjustified arguments. Thus we are forced to assume that we know how to know the truth, creating fundamentally inescapable uncertainty at the heart of all knowledge.

Fundamental uncertainty about what’s true might sound like a philosophical puzzle, irrelevant to daily life, but it lurks in the shadows behind every question we ask. Even simple questions like “what does this word mean?” and “what’s the right thing to do?” are complicated by uncertainty. And for our most difficult questions, fundamental uncertainty is often why we cannot, despite our best efforts, find satisfying answers.

Thankfully, we can learn to work with, rather than against, fundamental uncertainty. It’s not easy, but by learning to accept the limits on our ability to know, we can give ourselves the tools to start making real progress towards solving the world’s most important problems.