I've never had a career. I've had a PhD in physics, a stint teaching, a decade in banking across various functions, and now I build AI products for a hedge fund. If you asked me at any point along the way what my "career" was, I wouldn't have had a clean answer. What I had was a sequence of contexts: a combination of skills and curiosity that happened to be valuable.

When I was growing up, a career meant something specific and stable. You picked a category, engineer, doctor, banker, lawyer, and you progressed through it for life. The category was large and durable enough to sustain millions of people for life. These professional categories were oceans: vast, deep, and slow to change. Everybody swam in the same water and competed for the same roles.

That world seems to be ending with AI specializing work so fast. The person who understands how to apply AI output to credit risk in emerging market debt under a regime of high inflation isn't a "quant". They have a short-term gig addressing a small population, until the problem reshapes itself into something new. Then they move. Professional categories, the oceans, are fragmenting into smaller and more numerous puddles.

Ben Thompson recently described a version of this on the Cheeky Pint podcast, framing AI as enabling people to create their own "ponds" rather than competing in someone else's market. In my view, what's forming is more like puddles: smaller, shorter-lived, and more numerous. They form where conditions are right, sustain what they sustain, and when they evaporate, the water reconstitutes somewhere else.

Instead of one career that lasts a long time, you will have dozens of distinct professional identities, each defined by a specific intersection of skills, domain knowledge, and timing. A critical skill becomes knowing how to move to where the next puddle is forming before the current one dries up.

While the old model looked stable, it had a brutal feature: millions of people competing for the same roles with the same credentials along the same dimensions. This often led to unfairness. Fragmentation changes that equation. More puddles means more surface area for a specific combination of talent and judgment to be genuinely valuable rather than commodity labor in a massive pool.

But careers provided an identity. "I'm a lawyer" is a complete sentence that tells everyone who you are. Puddles require you to be comfortable with impermanence, and to trust that the next opportunity will form even when you can't see it yet.

Not sure if this take will hold the test of time, but here goes: I believe that puddles are forming. AI is accelerating career fragmentation in ways that will make the last decade of internet-driven disruption look gentle by comparison.