I'm also skeptical about the magnitude of their effect, but I wouldn't entirely discount it, either. The actual campaigns are limited in what they can do. They

I'm also skeptical about the magnitude of their effect, but I wouldn't entirely discount it, either. The actual campaigns are limited in what they can do. They can buy a lot of advertising that insinuates terrible things about their opponent, but they can only lie so much before they are subject to defamation charges. They can't get away with paying operatives to pretend to be the other side, "concerned" about something the candidate did or said. I don't know how effective such tactics really are. It's entirely possible that they lay a groundwork of negativity: "Sure, that troll on the Internet might have been lying, but maybe that just means that this less-unbelievable thing is actually true." It's impossible to measure. But in an election that's close, it doesn't take much, especially with the Electoral College. Elections swing on a few thousand votes -- a microscopic fraction of the ~150,000,000 votes that are cast. So I concur that the effect is probably small. But I'm not so sure that the small effect is unimportant. It gets to shift things in ways that the campaigns, and even the supposedly non-aligned SuperPACs, can't do.