At this stage in the race, most people know who they want to vote for. But given the options at hand, no matter who you think you'd prefer, it's hard not to feel concerns.
The debates are mainly a chance for voters to either reconfirm their instincts or realize that those nagging concerns at the back of their minds are just too much to ignore. So the job of each candidate last night was to give people the reassurance they need. And the question coming out of the debate is whether that actually happened.
Let's take a look at how each candidate did at defending and parrying their vulnerabilities, using a scale of 1-5 (1 means they made the problem even worse and 5 means they put it to bed).
Trump: Did he debunk these concerns?
Some voters clearly like the idea of Trump upending Washington – but not to the point where he could enmesh us in warfare and conflict on a regular basis.
Trump didn't come off as overly unstable but veered in that direction a few times – the birther issue, his temperament, and, weirdly going on about lawsuits he faced. He didn't make the allegations of being unstable meaningfully better or worse, so he gets a 3 on this issue.
Trump seems to so regularly make false statements, it's almost as if his supporters are completely inoculated to them. Hillary pushed hard on this point a few times, especially on his position on invading Iraq.
Trump didn't come off as overly untruthful, though his vagueness on so many issues also didn't help (also, by constantly describing his business as "unbelievable", you start to wonder what is believable). He gets a 3 on this issue too.
(3). Not qualified/ knowledgeable
In some ways, by running as the outsider, Trump has managed to mitigate his lack of knowledge and qualifications.
Trump didn't come off as overly unqualified, although by staying on message to the exclusion of anything newly persuasive, he reassured his supporters but didn't convert many people. He gets a 3.5 on this one.
Clinton: Did she debunk these concerns?
(1). No argument for running other than ambition
Clinton's been running (or preparing to run) for president for nearly a decade and still can't really articulate why (other than that it's her turn and she wants it). The American people tend to instinctively reject these types of candidates, unless they really hate the alternative (like Bush over Dukakis).
She did a very good job rebutting this attack and making a proactive case for what she believes in. While she didn't provide an overall vision or rationale for running, she came off as clearly qualified, knowledgeable and capable. She gets a 4.5 on this issue.
Clinton's struggles with honesty have been a major theme of the campaign but was not a major theme of the debate. She parried the email issue reasonably well (and he didn't press it for some reason) and only came off untruthful on TPP. She managed to avoid a major weakness, earning her a 4 on this issue.
Allegations of corruption have dogged Hillary throughout the campaign, but not once during the debate (even when she provided Trump with openings like mentioning a special prosecutor or her Congressional hearings). She emerged totally unscathed on this front, earning a 4.
So who won? In my calculation, Trump did far less to stem his liabilities than Hillary did (by my count, she scored 12.5 and he scored 9.5). Neither of them probably lost much support, but she likely stemmed the momentum against her and he likely didn't convert anyone new to his camp.