Tentative rule of thumb: if they don’t appear obsessed with details you regard as irrelevant they’re probably not actually an expert
— David R. MacIver (@DRMacIver) June 13, 2012
It seems to have struck a chord, so I thought I’d elaborate slightly.
Firstly, this is of course a heuristic for non-experts to determine expertise in a field with which they are only passingly familiar. If you are an expert then using your own lack of knowledge as a heuristic isn’t very useful, and you probably have much better ones to apply.
The basic idea is this:
It’s usually not obvious what the important features of a problem are. In particular what looks important is often different from what’s actually important, or requires you to address some more fundamental issue as part of dealing with it. Therefore your perception of relevance as a non-expert probably has an awful lot of false negatives.
Someone who has acquired expertise in a subject understands it a lot better, and thus has a much more finely tuned perception of what the relevant problems are. Therefore there are a lot of things they would consider relevant that you would not.
- Why is this developer talking about things like “refactoring” and “testing” which you don’t care about. You just want the software to get new features quickly and not crash!
- Why is that security person asking all these strange questions about validation? You just want to make it so people can’t hack your site
- Why is the tennis coach obsessing about where your feet are? You just want to hit the ball!
- Why is this cook talking about knife skills? You just want to know why your food isn’t cooking evenly!
I’m not 100% sure how useful the heuristic is. I suspect it may be too permissive in the sense that it’s easy to let babble through. e.g. “Why is this guru talking about chakras? You just want your cancer to go away!”. Perhaps it needs the secondary heuristic that they have to be able to explain why the detail is important?