It becomes clearer every day that Barack Obama, a historic president, presided over a somewhat less than historic presidency. With only one major legislative achievement (Obamacare)—and a fragile one at that—the legacy of Obama’s presidency mainly rests on its tremendous symbolic importance and the fate of a patchwork of executive actions. How much of that was due to fate and how much was due to Obama’s own shortcomings as a politician is up for debate and is a question that emerges from Princeton historian Julian Zelizer’s new edited volume, The Presidency of Barack Obama. With contributions from seventeen historians, the...