Historians often judge presidents by how effectively they respond to crises.

The George W. Bush presidency, for example, will always be seen through the prism of the Sept. 11, 2001, terrorist attacks. Historians also will be debating the war in Iraq for many decades to come: Was it necessary, was it executed properly, did the president know what he was getting into—and have any idea how to get back out?

Herbert Hoover’s ineffective response to the Great Depression will forever condemn his presidency, while Franklin D. Roosevelt’s activist response to the Depression he inherited from Hoover—equally ineffective overall—has earned his presidency unwarranted high praise.

The presidency of John F. Kennedy is evaluated in part by his resolve during the Cuban missile crisis, a crisis he needlessly helped create. This brought us to the brink of nuclear abyss, but burnished Kennedy’s reputation. After the failed Bay of Pigs invasion 18 months earlier, which fueled the missile crisis, the young president needed the boost.

Lyndon B. Johnson’s moment of truth—or untruth, as history now indicates—came in August 1964, when North Vietnamese PT boats allegedly attacked a U.S. Navy destroyer in the Gulf of Tonkin, off Vietnam. Johnson administration officials alleged two attacks on two separate days. We now know there was just one incident—and the U.S. was on offense, not defense. Johnson used the incident to drum up congressional support for dramatically escalating U.S. military involvement in Vietnam—a bad decision that generated an unpopular war, damaged his reputation, and ultimately cost him his job.

Ronald Reagan, praised excessively for his assertive role in “winning” the Cold War, in the process helped create the biggest threat to the American homeland since the War of 1812: al-Qaida. Reagan, in his anti-communist zeal, also secretly subverted the central power retained by Congress under the Constitution—the decision to fund federal programs—during the Iran-Contra affair.

As Zachary Karabell, biographer of President Chester Arthur, lamented, “Presidents who govern during time of calm and prosperity often suffer the barbs of history,” and are either ignored or written off as inconsequential. Those who adopt an active response when faced with major problems generally are deemed heroic—even if their response was the wrong one or the calamity was partly (or totally) of their own making.

A biographer of President James Polk, John Seigenthaler, has written that “presidents who combine a mesmeric personality with dynamic performance in times of crises” usually are rated the highest.

The truth is that most presidential scholars have a bias toward activism rather than outcomes. A president who creates new government programs to deal with societal problems will generally be seen as a better president than one who deals more cautiously—and cost-effectively—with problems. This is true even if those programs do little good, or even exacerbate the problems. Thus, despite Vietnam, President Johnson is viewed by many as a well-above-average president because he also declared war on poverty with a multitude of Great Society income-transfer programs, from Food Stamps, enacted in 1964, to Medicaid and Medicare, which became law a year later.

As we now realize, many of Roosevelt’s economic-recovery programs were wasteful and ineffective. And many of Johnson’s Great Society programs increased government dependency among the poor and made poverty more intractable. Yet, FDR and LBJ consistently are rated ahead of President Martin Van Buren, a low-key chief executive who promoted recovery from the economic panic of 1837 by using restraint in government and letting the market correct itself. This very restraint should earn Van Buren high marks.

Presidential performance ratings should be based on results—not rhetoric, personality, popularity, preference for basketball over bowling, or even crisis-management abilities, except to the extent that these qualities produce the right outcomes.

Results, moreover, should be measured not by the number of new laws passed or the number of new international “partners” the president aligns with the United States, but by the degree to which his actions, or deliberate inaction, contribute to peace, prosperity and liberty, which should be every president’s priority.