Whiteboard Markers & Black Swans

A valuable lesson for me today in heuristics vs rules & black swans…


I had a rule:

“Markers with white bodies are for the whiteboard”

This worked well for making sure we didn’t use sharpies on the whiteboard as the whiteboard pens actually had white bodies.

I’d never seen a white bodied marker that was a permanent marker – that was until today.

Just goes to show a cursory glance might have saved me some mild embarrassment…

So now my rule is a heuristic & I will always be checking the marker, regardless of its colour.

And here’s a link just in case you need to remove permanent marker from a whiteboard