A useful role exists for the economist is making calculations of the prospective costs and/or benefits of alternative policies. This role is precisel… - George Stigler

A modern economic system is of extraordinary complexity. Imagine a three-dimensional jigsaw puzzle, consisting of roughly 100 million parts. Some parts touch against, let us say, 1,000 other parts. (That is, each family deals at one time or another with that many employers, banks, retail stores, domestic servants, and so on.) Other parts touch—let us be conservative—50,000 other parts (firms that sell to retailers and buy from other firms and hire laborers and so on). It would be enough of a task to fit these 100 million pieces together, but the real difficulties have yet to be mentioned. The pieces change shape quite often—a family has twins; a firm does the next best thing and invents a new product. The economist has the interesting task of predicting (in the aggregate) each of these movements. Meanwhile a busy set of people—congressmen, members of regulatory bodies, central bankers, and the like—are changing the rules on who or what the jigsaw pieces will be and how they are shaped. And of course there are other jigsaw puzzles (foreign economies) of comparable complexity, and these other puzzles are connected at literally a million points with our puzzle.

Price dispersion is a manifestation — and, indeed, it is the measure — of ignorance in the market. Dispersion is a biased measure of ignorance because there is never absolute homogeneity in the commodity if we include the terms of sale within the concept of the commodity. Thus, some automobile dealers might perform more service, or carry a larger range of varieties in stock, and a portion of the observed dispersion is presumably attributable to such differences. But it would be metaphysical, and fruitless, to assert that all dispersion is due to heterogeneity.

One should hardly have to tell academicians that information is a valuable resource: knowledge is power. And yet this occupies a slum dwelling in the town of economics. Mostly it is ignored.