Market Pundits Walk Fine Line Between Hot and Has-Been

J.P. Morgan -- the Bill Gates of the 1890s -- was constantly being asked about his expectations for the stock market. His standard response, "It will fluctuate," is still famous today because of what it implies: If a guy who's smart enough to become richer than most countries isn't sure where the market is going, then maybe it, like the rest of the future, is inherently unpredictable.

Most investors accept this in theory. But in practice, uncertainty is uncomfortable -- especially when it comes to money. So no matter how many times we get burned trying to time the market, we're always open to the next guru with a string of good calls. And we're always a little sad when a big, unexpected market move exposes our favorite pundits for what they are: Very smart humans who, like the rest of us, are stuck in the present without a functioning crystal ball.

My first brush with this syndrome was back in 1982 when a flamboyant technician named Joseph Granville built a following that let him move the markets with a press release. One of his sell recommendations sent the Dow down 28 points, the equivalent of 300 points today in percentage terms. ...