The table demonstrates the pattern. Imperial presidents perform better than limited-power republican presidents. Average presidents are found in both categories, but within the extremes—the great and the terrible—there are only two modern exceptions. Eisenhower was a good president who did not try to expand his power, and Nixon was a bad president who did. Indeed, Nixon alone is probably responsible for the modern view that the imperial presidency is the worst kind of presidency. But if a constitutionally weak presidency prevents another Nixon, it also prevents another FDR or Lincoln. Although once in a while an Eisenhower could come along, most of the time we would have to make do with a Jimmy Carter, a Gerald Ford, or a Millard Fillmore. Such a state of affairs would hardly be appealing.

This argument, of course, is open to several objections. First, the character of the president might explain more than the power of the presidency. Lincoln and FDR might have been great presidents even if they couldn’t have exercised as much power as they did. But it seems just as likely that a limited office, with limited powers, would not have attracted a person with a powerful character; or else, such a person would have overreached and been blocked by other institutions such as congress and the courts.

Second, the ratings themselves may reflect the scholars’ emphasis on heroic traits rather than actual contributions to the welfare of the nation. A weak presidency implies more power is invested in institutions such as congress, state governments, and courts. However, it’s hard to find a single historical example in which these institutions produced great achievements during a weak presidency. In contrast, the most ambitious and successful legislation—including the Social Security Act of 1935 and the Civil Rights Act of 1964—has almost always been propelled by an imperial president.

Finally, many are concerned that the great imperial presidents set the stage for the awful ones. The familiar argument is that FDR established precedents that would be used by Nixon. But FDR also established precedents that would be used by Truman, Eisenhower, and Reagan.

None of this is to say that presidents should be unconstrained. They would then be dictators. Popular elections, a two-term limit, congressional participation in ordinary legislation, and judicial limitations are all good and necessary, and no one today would object to them. But much of the structure of the presidency—especially in foreign affairs—is hampered by 18th century restrictions that were motivated by fears of monarchy. By pushing against these restrictions, Bush is not bolstering a dangerous and all-powerful executive as much as he is further modernizing the office of the presidency and preparing it for the challenges ahead. Bush’s critics should argue with the way the president is using his powers, not the fact that he is expanding them.