Stock prices are likely to be among the prices that are relatively vulnerable to purely social movements because there is no accepted theory by which to understand the worth of stocks....investors have no model or at best a very incomplete model of behavior of prices, dividend, or earnings, of speculative assets.

Physicists have a bias to aspire to be "seers" like Einstein rather than "craftspeople" who do simple and practical research. I have seen that in economics departments. The same must be true to some extent in other departments.

My father, Benjamin Shiller, told me not to believe in authorities or celebrities - that society tends to imagine them as superhuman. It's good advice. People are snowed by celebrities all the time. In academia people have this idea of achieving stardom - publishing in the best journals, being at the best university, writing on the hot topic everyone else is writing about. But that's what my father told me not to do. He taught me that you have to pursue things that sound right to you.

Marketers know that if people you respect - perhaps laughably including entertainers and athletes - say they like a product, you're more likely to buy.

A major boom in real stock prices in the US after Black Tuesday brought them halfway back to 1929 levels by 1930. This was followed by a second crash, another boom from 1932 to 1937, and a third crash. Speculative bubbles do not end like a short story, novel, or play. There is no final denouement that brings all the strands of a narrative into an impressive final conclusion. In the real world, we never know when the story is over.

The ability to focus attention on important things is a defining characteristic of intelligence.

Economists who adhere to rational-expectations models of the world will never admit it, but a lot of what happens in markets is driven by pure stupidity - or, rather, inattention, misinformation about fundamentals, and an exaggerated focus on currently circulating stories.