sf-isms.a field guide to san francisco slang

noun · first recorded 1988 · status: og

Forcing function

1.A constraint you build on purpose so you can't back out: the demo you announced before writing the code, the launch date, the lease. SF's answer to discipline is engineering a situation where discipline is no longer optional.

He announced the launch date before the repo existed. Not recklessness: a forcing function.

01Origin

The term comes from design and engineering, canonized in Don Norman's 1988 The Design of Everyday Things: a forcing function is a constraint that physically prevents the wrong action, like a car that won't start out of park. The concept was about preventing errors. SF read it and asked the only question SF asks: can I point this at myself?

The local usage is entirely self-inflicted. You announce the launch to create the deadline. You book the demo slot before the demo works. You hire before revenue so the payroll forces the revenue. Demo day is a forcing function with an audience; the mixer was a forcing function for an entire city's dating life. The logic is always the same: motivation is unreliable, so replace it with consequences.

The tell that it's an SF-ism is its migration into biography. Moving in together is a forcing function. The wedding date is a forcing function for the proposal. The one-way flight is a forcing function for the resignation. It is high agency applied to your own future self, whom you correctly do not trust, and the load-bearing mechanism under every lock-in: you do not need willpower if you have burned the boats and posted about it.

02Notable sightings

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04See also