[sneakymichael]

"If you can't write it down you can't do it." - elaborate?

[itronitron]

I think this might have two, maybe more meanings. The first is that if the person asking you to do something won't put it in writing, then it's probably not legal and therefore you can't do it. The second is that if you haven't thought through something well enough to write it down (the problem and the solution) then you haven't thought about it long enough to have found a solution.

[ByThyGrace]

Maybe it means that the ability to spell out the entirety of the work process is an indication of the ability to fulfill the task.