Ran into the phenomenon of an "expert beginner" in one of the mailing lists that I subscribe to. It immediately stuck a chord as I've run into lot of people in my career (and I myself have been one, though I'd like to believe occasionally). Expert beginner is a dangerous (to the health of the team) person who is neither an expert (therefore we can't trust the person's judgement), nor is a beginner. The big problem is that he/she believes he/she is "indeed an expert". They have stopped learning having maxed-out (at a local maxima), and have beliefs like "I know that I'm doing it right because, as an expert, I'm pretty much doing everything right by definition" and/or "If I don't know something, it must be easy or may not be worth looking at it".
This is how the author Eric Dietrich describes them:
Expert Beginners are developers who do not understand enough of the big picture to understand that they aren’t actually experts. What I mean by this is that they have a narrow enough perspective to think that whatever they have been exposed to is the best and only way to do things; examples would include a C# developer who pooh-poohs Java without ever having tried it
Found it interesting? You may want to read the two complete posts on this topic: