Barack Obama and John McCain are busy demonstrating that in close elections during tough economic times, candidates for president can be economically illiterate and irresponsibly populist.

In Raleigh, N.C., last week, Sen. Obama promised, "I'll make oil companies like Exxon pay a tax on their windfall profits, and we'll use the money to help families pay for their skyrocketing energy costs and other bills."

Set...