Back in the day, the unutterably brilliant Jon Postel framed what will forever be known as “Postel’s Law:”

Be conservative in what you emit, and liberal in what you accept.

It stems from RFC 761, and it was originally intended to guide the creation of computer-computer interactions. In a nutshell, the law describes the nature of a robust system: when sending to another system, adhere as closely to a rigid standard as possible, but when receiving data from another system, allow for as much variability as possible.

I’ve since taken this principle as foundational for computer human interaction. Humans are by nature vague, imprecise, and sloppy beasts, so the computer should be prepared to accept a great deal of variability from them, while delivering precision to them.

But lately, I’ve been musing on this as also a fundamental principle of human-human interaction.

It’s not a new idea. We all know humans are inaccurate, imprecise, and vague creatures; we’ve known it for centuries. But I think in the digital age we live in, it may be wise to revisit the brilliant scientist who made so much of it possible, and take some advice.

Postel’s Law is a principle of robustness, meaning it makes sure the system continues to work, even under stress. Think about it: isn’t that what we expect from, and even need in, human interactions?

A system that follows the path set by Jon Postel will continue to function in the presence of garbage input. Shouldn’t we do as much?

If I’m following Postel’s Law and you say something that I disagree with, or am even offended by, I don’t blow up. Also I don’t immediately cut you off. I try and make sense first of what you say, and if I can’t I say so and ask for clarification. In worst case, I identify the offensive bits, drop them, and get on with the meaningful ones. “Be liberal in what you accept.”

From the other side, “Be conservative in what you emit” means I don’t call you names. I don’t shout at you. I don’t call you stupid because you don’t see what I see.

I don’t make the claim that applying Postel’s Law to human-human interaction is either a novel or a unique idea. In times past it went by the names of courtesy and civility. “Turn the other cheek” could be part of it, as could “A soft answer turns away wrath.” Proverbs like this abound in the world’s Wisdom Literature.

But perhaps we need a new, digital, formulation of the policy to reach the citizens of this digital world.

I’m not saying be phony or two-faced. “Be liberal in what you accept” doesn’t mean that, nor does it mean be a doormat. I’m saying you don’t need to retaliate for every offense, you can pass on by, noting the bad behavior of your communicant, like a warning flag from a compiler.

I’m also not saying you have a license to be deliberately offensive or hostile, to abuse the protocol. “Be conservative in what you emit.” No matter how you’re treated, you treat others with a high standard.

I realize we’re none of us computers, so we won’t follow any protocol laid out for us perfectly. At bottom line, I’m saying we should all try to behave as civilly toward other people as our computer behaves toward other computers, thanks to Jon Postel.