Many writers of investment books approach the topic of saving and investing without any clear economic theory. Value investors often share the sentiments of fund manager Peter Lynch, who said, "If you spend 13 minutes a year on economics, you have wasted 10 minutes."

At the other end of the methodological spectrum, MBAs trained in efficient portfolio theory disdainfully characterize the suggestion that investors should at times not hold any stocks in their portfolios as "market timing" — the investment world’s equivalent of casino gambling.

It is not possible to approach macroeconomic questions without an economic theory. A sound economic theory may or may not yield any useful insights for investors, but a false one is almost certain to mislead.

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