Who was the greatest baseball player of all time? Some people say Willie Mays. They emphasize that he had all of baseball’s “five tools”: he could run, hit, field, throw, and hit with power. Other people insist on Ty Cobb, who had the highest career batting average in baseball history. Still others say Cy Young, on the ground that good pitchers are more important than good hitters, and Young won more games than any pitcher who ever lived. Joe DiMaggio has his advocates, who note that he had the longest hitting streak in baseball history, and who emphasize that hitters, unlike pitchers, play every day. Still others say Hank Aaron, who had the most career home runs (except for Barry Bonds, whose all-time record was marred by steroid use).

It is certainly possible to rank baseball players in terms of batting average, wins, hitting streaks, and home runs. But people vigorously disagree about the relationship among those particular rankings and overall “greatness.” Can we mediate these disagreements? Baseball statisticians are trying. After all, the goal of a baseball player is to help his team to win. Maybe we can measure greatness in baseball by exploring how much a player contributes to wins. In fact, a statistical measure called Wins Above Replacement Player (warp) tries to isolate each player’s contribution, by specifying how many wins a player adds, compared with a standardized lesser player (say, a player who does not normally make it into the starting lineup). It turns out that Mays had 156 warp over his career, Cobb 151, Young 168, DiMaggio 78, and Aaron 142. With these numbers, we might be inclined to conclude that Young was baseball’s all-time greatest player (with the exception of Babe Ruth, who heads the warp list at 184).

Whatever its limitations, warp is a far better measure than imaginable alternatives. To identify the greatest baseball player of all time, it would not make a lot of sense to use some kind of poll or referendum. People might choose a recent player, because he is familiar to them or because he is their personal favorite. (David Ortiz, president of Red Sox Nation, might do well this year.) Not knowing about statistics, people might rely on a measure, such as batting average, that is not a valid test of baseball greatness. A poll would enable us to identify the player that polltakers favor, but unless their own measures are fairly reliable, it will not tell us a lot more than that. As compared with polls, statistical analysis has real advantages.

And who was the greatest president in American history? Reasonable people might say George Washington, Abraham Lincoln, or Franklin Delano Roosevelt. But how is presidential greatness measured? Can we devise a warp for presidents—something like Wins Above Replacement President? If so, we would need to specify the functional equivalent of “wins.” Maybe the term would refer to economic growth or to wars averted or to wars won, controlling for historical circumstances; if so, we would need to produce some kind of measure twhat would aggregate presidential “wins.” The problem is that history is run only once. Outside science fiction, it is not possible to say what a Replacement President would have done, and to specify how things would have turned out if he had done it. In the fullness of time, we might be able to make some progress in measuring presidential greatness in statistical terms, but it is not exactly surprising that, to date, rankings of presidents tend to rely on polls, flawed as they are.

And what about religious leaders, scientists, philosophers, artists, and novelists? Can they be ranked as well—in terms of greatness or importance? Might we be able to play some kind of Moneyball with Joyce Carol Oates, Stephen King, James Joyce, Charles Dickens, and Thomas Hardy? Can cultural figures from diverse fields be ranked against each other? How might we compare Einstein, Plato, Descartes, Hume, Michelangelo, Suzanne Farrell, and Bob Dylan? True, it might be ridiculous, or even a bit crazy, to try. Skeptics might wonder about the point of such efforts: what kind of game is this? This is a good and potentially devastating question, but if we want to understand the arc of history and the nature of social influence, the endeavor might turn out to be interesting and perhaps even worthwhile. (And besides, many people find it fun.)