There are domains in which expertise is not possible. Stock picking is a good example. And in long-term political strategic forecasting, it's been shown that experts are just not better than a dice-throwing monkey.

The effort invested in 'getting it right' should be commensurate with the importance of the decision.

If there was one ubiquitous recommendation about marriage it was this: "Don't go to bed angry."

To know whether you can trust a particular intuitive judgment, there are two questions you should ask: Is the environment in which the judgment is made sufficiently regular to enable predictions from the available evidence? The answer is yes for diagnosticians, no for stock pickers. Do the professionals have an adequate opportunity to learn the cues and the regularities? The answer here depends on the professionals' experience and on the quality and speed with which they discover their mistakes.

In essence, the optimistic style involves taking credit for successes but little blame for failures.

Unfortunately, skill in evaluating the business prospects of a firm is not sufficient for successful stock trading, where the key question is whether the information about the firm is already incorporated in the price of the stock. Traders apparently lackthe skill to answer this crucial question, but they appear to be ignorant of their ignorance.

There's a tendency to look at investments in isolation. Investors focus on the risk of individual securities.