Postel’s Law and the Art of Working with Humans
Postel’s Law, also known as the Robustness Principle, comes from the early days of the internet. It states:
“Be conservative in what you do, be liberal in what you accept from others.”
— Jon Postel, 1981
It was meant to help build systems that could cope with unpredictable data, a web built not just on rigid standards, but a bit of patience and grace.
And while it was written for machines, I’ve always thought it sounded like good advice for working with people.
The human version
In L&D, we spend a lot of time creating structure. Rules, processes, checklists, learning objectives, assessment criteria, all useful in theory, but the real world doesn’t always behave the way we’d like.
People misinterpret instructions. They forget things. They learn in unexpected ways. They bring context, pressure, stress, humour, and history with them, and we don’t always catch it in the design.
If we followed Postel’s lead, we might take a slightly different stance:
Be precise in what you build. Be generous in what you expect.
That doesn’t mean dropping standards, but recognising that we’re not the only ones with a system to run. Everyone’s interface is messy.
How this shows up in our work
You see Postel’s Law at play when:
A learner uses your course to solve a different problem than the one you designed it for
A manager delivers your carefully crafted training in a 15-minute huddle and still gets results
A team ignores your eLearning entirely, but applies the checklist you posted in the break room
It’s not a failure of your design. It’s a reminder that if people get what they need, even by accident, we should probably consider that a win.
What it means for L&D
There’s a lesson here in humility. We can build clean, elegant learning paths, but once they’re out in the world, people will do what they need to do. They’ll adapt, ignore bits, and use the material out of order, in a hurry, while being asked for three other things. And if our goal is performance, not perfection, then maybe that’s okay.
So let’s keep building with care. Let’s write with clarity and structure for sense. But let’s also expect mess, plan for it, and leave room for it. Because in the end, the best systems and the best learning experiences are the ones that stay useful even when things don’t go to plan.