Like Noah Millman , I don’t expect to learn anything from tonight’s presidential debate. For those of us that have followed the campaign from the beginning, both of these candidates are thoroughly familiar, and even for people that haven’t paid close attention to the election both Clinton and Trump are very well-known (and not coincidentally deeply disliked by most). There will be no meaningful revelations about either candidate, nor are many people going to be swayed by what they see and hear. It will mostly be an exercise in avoiding self-inflicted wounds, and the one that comes out with fewer unforced errors will likely be deemed the winner.
Trump has never been interested in outlining policy proposals in any detail during debates, and he isn’t going to start now. That gives him a slight advantage in that most voters don’t especially care about policy specifics, and tend not to react well to candidates that are absorbed with them. If there is one thing Trump knows about, it is how to perform on television, so I don’t know that it matters so much that this will be the first head-to-head debate he has done as a candidate. Clinton has considerably more experience with these formats from both her Senate and presidential campaigns, but she has never faced off against an opponent quite as shameless and unconventional as Trump. Clinton probably has the edge in being able to give the canned, scripted answers that these events demand. Trump’s willingness to say almost anything means that he may surprise her with an attack or proposal that she isn’t anticipating.
The debate “topics”  that have been announced in advance are very vague, but I assume “securing America” will be the section of the debate related to foreign policy and national security. Because of her tenure at the State Department, this is the section during which Clinton will be expected to dominate Trump, who knows little and understands even less about the rest of the world. However, because of her record of poor judgment on foreign policy, especially as it relates to military intervention, Clinton will be vulnerable to attacks that Trump won’t hesitate to make regarding the Iraq and Libyan wars. Trump may be a lousy messenger for these criticisms, but they are attacks that she was mostly spared during the primaries and for that reason she hasn’t had much practice in defending against them. This section of the debate seems likely to serve as a microcosm of the election as a whole: Clinton has experience but also has lousy judgment, while Trump is a shameless opportunist who doesn’t know much except for how to take advantage of his opponents’ poor records.
P.S. I will be covering the debate tonight on Twitter (@DanielLarison ). The debate begins at 9:00 p.m. Eastern.