Politics & Power Quote by Jon Postel

Postel’s line reads like etiquette, but it’s really infrastructure politics disguised as a virtue. Written into the DNA of the early internet (as the “robustness principle” in TCP), it’s a compact governing philosophy for systems built by strangers who don’t fully trust each other and can’t afford to stop talking. “Conservative” here isn’t ideology; it’s engineering discipline: make your software predictable, restrained, and standards-compliant so you don’t spray chaos into a shared network. The quiet sting is that the burden is on you. Don’t externalize your sloppiness.

Then comes the pragmatic generosity: be “liberal” in what you accept. In the messy reality of interoperating machines, perfection is an enemy of connection. Packets arrive malformed, implementations vary, documentation lies. Postel’s advice is a survival strategy for a network meant to route around failure, including human failure. Tolerance becomes a tool for resilience.

The subtext is a particular early-internet faith: interoperability is worth bending for, and the commons grows when participants absorb friction instead of amplifying it. It’s also a warning we only fully appreciated later. Being too liberal in acceptance can harden bad behavior into de facto standards, mask security problems, and reward noncompliance. What began as a principle of robustness can mutate into a permission slip for carelessness.

That tension is the quote’s lasting power: it captures the internet’s original moral bargain - I will restrain myself so we can all keep communicating - and foreshadows how easily “be tolerant” can be weaponized by the least responsible actor in the room.