"Consumer spending accounts for about 70% of all demand in the U.S. economy."
Our last economic boom was fueled by greed and ignorance, as our next one will be, but should we truly educate our children to focus on what matters, on what makes a good life, to critically analyze their choices, well, there's going to be a lot less "consuming" going on.
A deep understanding of "the economy" requires knowing some biology and a lot of agriculture. You can only get so many turnips out of an acre of ground, and we can live the way we have lived, borrowing and borrowing, for only so long. Biologists recognize limiting factors to growth.
If by the economy, Duncan means a grasp of how we obtain and allocate the things we need to live, recognizing our limits, factoring in the cost of our wastes, then yes, he is right--we can educate our way to a better economy.
If, however, Duncan means The Economy, the abstract world of huge numbers flickering in the CPU for milliseconds, wheat futures based on an unpredictable climate, and the myth that the new economy keeps us immune from Malthusian catastrophe, well, then our Secretary Education shows that even a Harvard education can go terribly wrong.