Lower taxes, House Speaker Newt Gingrich told a national radio audience last Saturday, mean "less time at work and more free time, so you can be a better volunteer, a better parent, more active in your community, and more involved in charitable activities." That's curious. For more than a decade the supply-side tax cutters of the GOP have been telling us that cutting taxes would spur more, not less work effort, thereby speeding economic growth and replenishing the Treasury. In fact, economic theory tells us, lower taxes do have contradictory effects--they prompt us to work harder, because we net more from each hour of labor, and to goof off because higher total take-home pay means we can satisfy our needs more easily. For each individual the relative strength of the two effects may differ, but for the society as a whole there is a net result. Either you get more work effort in the aggregate, or less. You can't have it both ways.