A few weeks ago I realized I had been making the same call repeatedly for months — and the reasoning behind it was something I’d decided back in January without actually testing it.
The call felt right. The reasoning felt solid. But when I finally sat down to articulate why I was making it, the justification was basically: “this seemed right when I set it up.”
That’s not a reason. That’s just inertia wearing the costume of a decision.
How assumptions turn invisible
The first time you make an assumption, it usually has some backing behind it. You looked at the situation. You made a judgment call. You moved on.
The problem is that “moved on” often means the assumption gets absorbed into how you operate. It becomes infrastructure. It stops being visible as a choice and starts being visible as just how things are.
You stop checking it because it’s working — or at least, it’s not visibly broken.
That’s the trap. “Not visibly broken” and “actually correct” are not the same thing.
The cost of inherited logic
Every system you build rests on assumptions you made when you built it. Some of those assumptions are load-bearing. Others are artifacts of the context you were in when you started — constraints that no longer apply, guesses that were never confirmed, shortcuts that made sense at the time.
The trouble is, the system doesn’t tell you which is which.
It just runs.
And as long as it runs, you have every incentive not to poke at it. Poking might break something. Poking takes time. And if you did poke and found a flawed assumption, you’d have to do the uncomfortable work of unwinding whatever was built on top of it.
So you don’t poke.
The assumption keeps running, unchecked.
What actually surfaces them
In my experience, flawed assumptions don’t surface through reflection. They surface through friction.
Something breaks in a way that surprises you. A decision that used to feel automatic starts generating questions you can’t answer cleanly. You bring someone new in — a colleague, a collaborator, an outside eye — and they ask an obvious question that you’ve never actually asked yourself.
“Why does it work this way?”
And you realize the answer is “because that’s how I set it up,” which is not the same as “because that’s correct.”
That moment is useful. Annoying, but useful.
The problem is that you can go a long time without it arriving. Especially if your environment is mostly stable. Especially if the people around you are used to how things work and have stopped questioning it too.
The check I try to run now
I’ve started being deliberate about this once a month. Not a full audit — that’s too heavy to actually do. Just one question, applied to whatever I’m spending the most energy on:
What am I treating as given that I haven’t tested recently?
Not “what’s broken.” Most things aren’t broken. The assumption I’m looking for is the one that’s quietly correct until it isn’t — and I won’t know it’s wrong until the moment it matters most.
Sometimes I find nothing. The assumption holds up. That’s useful too.
Sometimes I find something small: a constraint that no longer applies, or a priority that got set in a different context and never updated. Those are easy to fix once you see them.
Occasionally I find something bigger. A foundational belief that’s been shaping several decisions downstream — and when I actually stress-test it, it doesn’t hold up.
Those ones are more expensive to unwind. But they’re also the ones that explain a lot of friction that was previously hard to diagnose.
The honest admission
The assumption I found this year was embarrassing in the way these things usually are: obvious in hindsight, invisible in the moment.
I’d made a call about how I was positioning something — what it was for, who it was aimed at — early in the process. And I’d never revisited it, even as the context had shifted.
Every downstream decision was consistent with the assumption. That’s actually why it was so hard to see. Everything looked coherent from the inside.
It just wasn’t coherent with how things actually were.
The fix was not complicated. The fix required looking directly at the assumption and asking whether it was still true.
The harder part was accepting that a lot of what I’d built on top of it needed a second pass.
Not a teardown. A correction.
That’s usually how it goes. The assumption wasn’t catastrophically wrong. It was just running past its expiry date.
Most of them are.