Playing off a very entertaining Kevin Drum post on the dismal history of “October Surprises” (dating all the way back to 1940!), Jonathan Bernstein offers a fine encapsulation of why such late-cycle shenanigans tend to have little effect on presidential election outcomes:

October Surprises are unlikely to matter to the outcome in November for exactly the same reasons that the debates are unlikely to matter, as John Sides explains it. Those include: most people have made up their minds by October; the people most likely to know about a news event are the ones most likely to have already decided; and partisans and other decided voters are apt to interpret the events through their own prior attitudes — that is, President Obama’s supporters are likely to heavily discount any new information they receive at this point, or simply just interpret it to fit in with their already-set belief that Obama is doing a decent job.

Jonathan goes on to acknowledge that external events (as opposed to debates or campaign speech and ads) can have an effect on elections by “changing the subject.” But even then, the effect is limited to voters who haven’t make up their minds and don’t process new information strictly through a partisan lens.

Earlier today I was talking to a BBC producer about a prospective appearance on Wednesday to discuss the first Obama/Romney debate. I allowed as how I was a skeptic about the game-changing potential of debates, and she responded that Brits were acutely aware of the 2010 impact of “Cleggmania” after LDP leader Nick Clegg’s impressive performance in a Leaders’ Debate prior to the last general election. I responded that UK elections lasted weeks, while ours lasted years. This may in fact be a rare advantage of our political system, insofar as Nick Clegg is now settling into a role as the least popular major national political figure in the United Kingdom.

In any event, I’d be surprised if the debates or any non-cataclysmic event had anything other than a marginal impact on the presidential elections. The contest may be close enough that “marginal impact” could ultimately be decisive, but in that case, many things that happened long ago could wind up mattering even more.

Ed Kilgore

Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.