The election of Donald Trump, and the early days of his presidency, have driven many Americans to rummage through history in search of context and understanding. Trump himself has been compared to historical figures ranging from Ronald Reagan to Henry Ford, and from Andrew Jackson to Benito Mussolini. His steps have been condemned as unprecedented by his critics, and praised as historic by his supporters.

To place contemporary events in perspective, we turned to a pair of historians of the United States. Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author, most recently, of The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society. Morton Keller is a professor emeritus of history at Brandeis University. He has written or edited more than 15 books, including Obama’s Time: A History. They’ll be exchanging views periodically on how to understand Trump, his presidency, and this moment in political time. —Yoni Appelbaum

Julian Zelizer: President Trump’s first 100 days in office are coming to a close. The grades will soon come out. Politicians, journalists, historians are all starting to evaluate how well or how poorly he has done. This does not go down in the “unprecedented” part of this presidency. Ever since President Franklin Roosevelt pushed through Congress a historic legislative agenda in the early part of his term, the 100-day mark has been a standard part of the political lexicon.

There are many reasons for why we keep using this measure. Once FDR set the bar, it became difficult not to make this comparison. For journalists the 100 day-mark is a nice, clean, and simple way to measure how things are going, while politicians look for ways to gauge the strength of the commander in chief. In our current culture of quick, instant satisfaction, we want presidents to deliver on promises right away—and we have little patience for waiting.

But the first 100 days in office don’t really tell us much. Some presidents who get off to a strong start, like Jimmy Carter, go on to struggle during the remainder of their terms. Others, like Ronald Reagan and Bill Clinton, have tough early months, but then go on to serve two terms and end their term with strong approval ratings. Some of the biggest presidential achievements, like President Richard Nixon’s trip to China or President Obama’s health-care reform, come long after the 100 days are over.

It’s also not clear what we should measure. In the current era of strong presidents, executive orders and action should certainly be part of what we evaluate. So, too, should actions by Cabinet leaders, as we see in the current administration when rightward leaning agency secretaries are working hard to undercut the missions of their own programs.

Putting too much pressure on success in the first 100 days creates incentives for quick, and sometimes hasty, action. Great legislation can take time to produce. The legislative process requires what political scientist Nelson Polsby called periods of policy incubation when experts revise and strengthen ideas, where policy makers build support for a bill, and when elected officials can evaluate what kind of legislation will work best. Doing everything up front and right away is often antithetical to success especially in a polarized age when “no” is usually the easiest answer to new ideas.

I am as guilty as anyone else for still using this concept but it is probably time to move on to other measures. Asking how presidents did in the first 100 days usually tells us little about what is to come and might even create the exact political incentives we need to avoid.

Morton Keller: The concept of the 100-day marker appears to have originated in the time between Napoleon’s leaving Elba and reinstatement as emperor in Paris, and the restoration of the French monarchy after Waterloo. It appeared in American politics with FDR’s first three months in office after his March 1933 inauguration. In both cases the term’s appeal lies in its implication of a revolutionary turnover in political events: Napoleon’s final removal from power, Roosevelt’s first New Deal.

The term has been applied in more recent times, and to more normal leaders, to describe their pivots from a determination to fulfill what were seen as their electoral mandates (usually without success) to more nuanced or even quite different policies (usually with some success). This was true of Ronald Reagan and Bill Clinton.

And what about Trump? You are quite right, Julian, to reserve judgment on that score. Initially, the new president seemed hell-bent on fulfilling his most fearsome nationalist, xenophobic, isolationist rhetoric. More recently, he has shown signs of leaning toward policies, personnel, and politics that are more mainstream than slipstream.

Which is it to be? Reinstatement of the Trumpian Revolution in all its often maleficent character, a la Napoleon after Elba? A modified, and ultimately more successful, reshaping of his initial policy intent, a la Reagan? Or a sea change in policy a la FDR or, less sweepingly, Clinton?

I am in full agreement with you that this is no time to attempt a conclusive assessment of what the Trump presidency is up to, and where it is heading. The media savants who explain politics to the masses appear to be quite certain of their positions, varied though they are. As historians, we are duty-bound to withhold judgment when the available evidence is as varied and conflicting as, just now, it is.

Zelizer: I’m glad we are in agreement on this one. I would add that the entire concept, as we commonly use it, does reflect a problem with our current approach to politics generally. As you taught me many years ago, and I keep learning, legislating just takes time and many tries. I was always struck when writing about the history of Medicare, that it really took almost a decade until legislators got it right. Many versions were tried, voted on, and revised until we reached the breakthrough of 1965.

I do think we have a president who has especially little appreciation for that, and won’t put much work into doing this with policies. But that’s for another conversation. At a minimum maybe we can give presidents 200 days?

Keller: When Harold Macmillan was asked what determined the course of British politics, he is supposed to have replied: “Events, my dear boy, events.” That was certainly the case with Clinton, who was shaken into a new policy course by the 1994 bye-election results (and perhaps by the spectacular failure of Hillarycare). Similarly, 9/11 turned George W. Bush from a rather inert president to one whose new-found reputation as a leader in the fight against terrorism may well have been the determining factor in his 2004 defeat of John Kerry.  

So why substitute the 100 days invention with a 200 days one? Why don’t we wait on events, and when in our judgment a substantive pattern is emerging, say so?