I was thumbing through a discussion between Davelj of Professor Piggington and Karl Denninger of Market-Ticker. The discussion itself is interesting and worth reading. However, what I'm including below is a comment by Davelj regarding the difference between experts and amateurs. It's poignant and I'm blogging on it merely to keep it for the record (Also on my Furl)

I've found that any reasonably intelligent person can learn/understand about 90% of almost any industry fairly quickly. The economics, critical profit drivers, financials, etc. The problem is that the last 10% is the only part that matters. That's what distinguishes real expertise from amateurs. There are a LOT of ninety percenters out there that don't even know what they don't know, although they will be quite dogmatic regarding those things that they think they know (but don't). Personally, I've exceeded the 90% threshold in two industries, one of which is banking. If I'm really lucky that number might get to three (or maybe four) before I die. As Mark Twain once said, "It ain't the things you don't know that get you in trouble; it's the things you know for sure that just ain't so." Just something to think about.