Ideas from the books — one at a time.
Behavioral theory you can use, and old stories sorted by the moment you need them. Most of these are adapted from Product Theory and Words; each one stands on its own.
Every incentive creates a game. The Cobra Effect is what happens when it's not the game you wanted—and why your best-looking metric might be the one breeding snakes.
People value what they build far beyond its objective worth. The best products don't just get used — they get built on. Here's how to design for it.
A distinguished professor watched a Zen master pour tea until it spilled across the floor. The lesson still lands: you can't fill a cup that's already full.
People don't stay in bad situations because they can't see better options. They stay because their brain protects the known from the threat of the unknown.
The seams in your product are copies of the seams in your org chart. That's not a metaphor — it's Conway's Law, and it predicts what your app feels like to use.
Three old stories about choosing well: the crossroads, the strawberry on the cliff, and the woman carried across the mud. What they teach about the moment of decision.
Most product decisions go wrong for reasons that already have names. Here are 12 mental models — what each one is, a concrete product example, and when it quietly lies to you.
Everyone knows the $9.99 trick. Everyone still falls for it. Here's why the last digit of your price is a positioning decision, not a math one.
Being stuck and going nowhere are not the same thing. Three old stories about the difference — and what to do when you can't see your own progress.
A fast-food chain couldn't sell more milkshakes—until they stopped studying the milkshake and started watching who bought it, and when. That's Jobs to Be Done.
The medium popcorn was never meant to sell. It was meant to sell the large. Meet the decoy effect—and why it lives on your pricing page.
Temptation rarely shows up as a villain. It shows up as a reasonable-sounding voice. Three old stories for the moment you're about to give in.
Direct advice about letting go bounces right off. A story slips past the guard and stays. Here are nine of the best — on control, grudges, outcomes, and certainty.
A real estate agent shows you an $800,000 house you don't love. The next one is $650,000, and suddenly it's a steal. You're not judging the house. You're judging the first number that entered your head.
Some of the things you carry are cracked. An old Indian folk tale about the leak you keep apologizing for — and the flowers growing on the trail behind you.
Past investment shouldn't influence future decisions, but it always does. How the sunk cost fallacy retains your users — and why the retention it buys you might be a prison, not a product.
Every chapter in Product Theory — the mental models behind how users price, choose, stay, and churn. Read the free essays or get the book.
Three old stories for the days the floor drops out from under you — and why the smartest response to disaster might be four small words.
The military wanted to armor the bullet holes. A statistician told them to armor everywhere else. The same mistake is quietly wrecking your product decisions.
Price isn't a number. It's a story people tell themselves about what something is worth. Here are seven rules — anchoring, decoys, charm pricing, mental accounting — that quietly decide what people buy.
The more useful something is, the harder we scrutinize its price. Why we under-invest in essentials, over-invest in indulgences, and how great products flip the switch.
DAU up. Churn down. Everyone nods. Meanwhile a user is quietly switching to a competitor. That gap has a name — Metric Theater — and it's killing your product.
Set a target, and your team will hit it — often without touching the thing you actually care about. Goodhart's Law explains why every metric you optimize eventually lies to you.