In defence of assumptions

Posted: 9th March 2017

"Never ASSUME, because when you ASSUME, you make an ASS of U and ME."

-- Jerry Belson

Because what else are you going to start a post on assumptions with[1]?

The obvious defence of assumptions is simple: in the vast bulk of cases it doesn't matter. We want to get on with our lives and we'll just have to leave that doubt behind and trust.

The defence that many things we assume don't matter isn't much of a defence though. The reason I think assumptions get a bad rep is that too often we mean untested or unstated assumptions not assumptions in general.

You make thousands of assumptions all the time. Being upfront and explicit about the ones you're using is only being responsible. Make it clear to others when you're making a guess, or will need to check something, and then get back to what's important.

A benefit to clear assumptions is they make finding what went wrong, what might go wrong or what is wrong becomes a lot easier. Assumptions are necessary so just be explicit about them. You'll always have to assume something at some point and that's OK: assumptions aren't the problem. Not checking nor stating them is.

[1]: I'm assuming that wikipedia is correct in attributing this to Jerry Belson but I'm not sure, and frankly, don't care... [back]