The ethical rule is from Samuel Johnson who believed that maintenance of easily removable ignorance by a responsible office holder was treacherous malfeasance in meeting moral obligation. The prudential rule is that underlying the old Warner & Swasey advertisement for machine tools: "The man who needs a new machine tool, and hasn't bought it, is already paying for it". The Warner & Swasey rule also applies, I believe, to thinking tools. If you don't have the right thinking tools, you, and the people you seek to help, are already suffering from your easily removable ignorance.
Charlie MungerWhen we were young, there weren't very many smart people in the investment world. You should have seen the people in the bank trust departments. Now, there are armies of smart people at private investment funds, etc . If there were a crisis now, there would be a lot more people with a lot of money ready to take advantage.
Charlie MungerFixable but unfixed bad performance is bad character and tends to create more of itself, causing more damage to the excuse giver with each tolerated instance.
Charlie MungerWhat matters most: passion or competence that was born in? Berkshireis full of people who have a peculiar passion for their own business. I would argue passion is more important than brain power.
Charlie MungerBlack-Scholes is a know-nothing system. If you know nothing about value - only price - then Black-Scholes is a pretty good guess at what a 90-day option might be worth. But the minute you get into longer periods of time, it's crazy to get into Black-Scholes. For example, at Costco we issued stock options with strike prices of $30 and $60, and Black-Scholes valued the $60 ones higher. This is insane.
Charlie Munger