It is remarkable how much long-term advantage people like us have gotten by trying to be consistently not stupid, instead of trying to be very intelligent.

Another thing I think should be avoided is extremely intense ideology because it cabbages up one's mind. You see it a lot with T.V. preachers (many have minds made of cabbage) but it can also happen with political ideology. When you're young it's easy to drift into loyalties and when you announce that you're a loyal member and you start shouting the orthodox ideology out, what you're doing is pounding it in, pounding it in, and you're gradually ruining your mind. So you want to be very, very careful of this ideology. It's a big danger.

You must force yourself to consider opposing arguments. Especially when they challenge your best loved ideas.

And maybe the cereal makers by and large have learned to be less crazy about fighting for market share-because if you get even one person who's hell-bent on gaining market share.... For example, if I were Kellogg and I decided that I had to have 60% of the market, I think I could take most of the profit out of cereals. I'd ruin Kellogg in the process. But I think I could do it.

The hedge fund known as "Long Term Capital Management" collapsed last fall through overconfidence in its highly leveraged methods, despite I.Q.'s of its principals that must have averaged 160. Smart people aren't exempt from professional disasters from overconfidence. Often, they just run aground in the more difficult voyages they choose, relying on their self-appraisals that they have superior talents and methods.

Failure to handle psychological denial is a common way for people to go broke: you have made an enormous commitment to something. You have poured effort and money in. And the more you put in, the more that the whole consistency principle makes you think, "Now it has to work. If I put in just a little more, then it will work."

I regard the amount of brainpower going into money management as a national scandal. When some idiot would get rich, they'd say, 'Well, old Charlie was out in the field playing the big brass tuba on the day it rained gold.' A lot of people have become rich lately who were playing the tuba on the day it rained gold.