I can believe it's too easy to believe that something non-obvious is obvious once you've understood it. But that doesn't mean that some things aren't legitimate

I can believe it's too easy to believe that something non-obvious is obvious once you've understood it. But that doesn't mean that some things aren't legitimately obvious. It seems like we ought to take an empirical approach to distinguishing which are which -- take skilled engineers either in groups or singly who haven't heard of a given solution, pose them the problem that the solution is meant to solve, let them brainstorm or think for some fixed amount of time, and see if anything they come up with largely reproduces the solution in mind. If fewer than k engineers are needed before someone thinks of it, then it's obvious. If more than l > k engineers are needed before someone thinks of it, then it's not obvious. If somewhere between k and l engineers are needed, then maybe you still get to argue about it. On a related note, I think I have a new strategy for generating interview questions.