Understanding customers in terms of what they cannot not do is a way to discover authentic demand and found a potentially successful company.

You can’t avoid doing the things that make you who you are. In a chess game, almost all the pieces can attack, defend, or be sacrificed for strategic reasons. But the king is an exception. If you are the king in a chess game, then the job you cannot not do is survive. The king can be a powerful attacking piece, or it can protect other pieces. But attacking and protecting are optional, they are jobs the king can avoid. Surviving is different; the king cannot not survive, because if it’s checkmated, then the game is over and it can’t be itself anymore. In our lives, you can’t be a leader if you’re not leading, a mother if you’re not mothering, or a developer without developing.

This sounds straightforward, but three things make it tricky:

First, many of the things we are are hidden. We hide them from others because they expose vulnerabilities, we hide them from ourselves out of shame, or we just don’t have the requisite self-knowledge. It can be really hard to ferret out what people are.

Second, many of the things we think or say we are are just lazy labels. Maybe I call myself a programmer, but really I spend my days managing programmers or evaluating other people’s work, and the actual writing of lines of code is something I have no trouble avoiding.

Third, paradoxically enough, we’re often not doing what we can’t avoid doing. People can’t avoid eating, but there are lots of starving people. Some musicians can’t avoid playing music but they’re forced by circumstance to spend their days driving cabs or waiting tables.

These people have internal or external constraints that prevent them from being who they are. Think of it like gravity. A marble rolling around in a bowl cannot not come to rest at the lowest point in the bowl. But the world around it might intervene with a constraint – maybe a cat bats the marble around, or someone holds it against the side of the bowl. Gravity is intrinsic to the marble and compels it to the bottom of the bowl, but there are lots of possible constraints or situations that might prevent it from getting there.

A customer is a person who is presently constrained to not be who they are. Something is holding them against the side of the bowl, preventing them from getting to the bottom.

For a customer, a product is a constraint remover. If I’m an on-the-go music listener, an iPod is a constraint remover. If I’m a downtown worker, the bus is a constraint remover. If I’m an educator, a textbook is a constraint remover.

When you know what a group of people cannot not do, you have something you can rely on to create a business. Reliability is the key, and it explains why “not not” is a better way to think about customers than want or need. There are plenty of things people want that they never go out and get, and meanwhile, there are plenty of things they buy that they never wanted. A startup cannot count on “want” to translate into sales.

In a chess game, you can’t count on the king to attack or defend, but you can count on him to avoid checkmate. That doesn’t mean the king will never be checkmated, but it does mean that, given a checkmate threat on the board, you know how he will move. The “not not” approach gives founders reliable insight into how their customers will move.