Obama supporters are tripping all over themselves, sputtering out Mitt Romney's "47 percent" line to anyone who will listen. This, they argue, is the real Romney! To his donors, when cameras aren't -- or at least aren't supposed to be -- rolling, Romney unveils his real beliefs! The phony, obsequious Romney we see on the campaign trail is revealed as the worst stereotype of a heartless conservative.

Conservatives, for their part, are thrilled by this peek beneath the veneer. This, they argue, is the real Romney! A bit coarse, but this is the rhetoric many wish they'd see on the campaign trail. This is the Romney they love.

That reaction from the right means that, in that room on that day, Romney was probably saying exactly the right thing. He wasn't there to be honest, he was there to accomplish his goal: getting wealthy conservative donors to pony up.

Mitt Romney is a habitual liar. But that's only because Mitt Romney is a perpetual candidate.

Students of politics will note that the most revealing thing said at either convention was this, by Michelle Obama:

Well, today, after so many struggles and triumphs and moments that have tested my husband in ways I never could have imagined, I have seen firsthand that being president doesn't change who you are -- it reveals who you are.

The First Lady meant this as a testament to the character of her husband, whose actions in the White House were the ones that voters could take to the bank. But, read another way, it was a tacit admission that the candidate -- Democrat or Republican -- who a voter or donor sees on the campaign trail is not necessarily who a candidate will be as an elected official.

We may as well disabuse ourselves that our elections are contests between two candidates presenting plans of action on tidy little platforms from which informed voters choose. It's an endearing idea, that we weigh the intentions of two earnest servants and negotiate our own beliefs to select the one we find most appealing. But it's naive. Candidates are job applicants presenting themselves to you. Like anyone else, they will present a resume that fits your job requirements while answering questions about their negative traits with a sly, "Maybe I work too hard!" Everything gets scrubbed down, worn away, sanded. Candidates know the audience to which they're speaking and present a shiny, blank slate for you to read into.

Candidates often ban cellphones at fundraisers not because they don't want the truth to be released, but because they don't want to pollute the message they've crafted for one audience with one crafted for another. Was Romney being more honest to the funders than he is to voters? There's not really any way to know. There's hardly much more incentive for him to present a completely honest accounting of his beliefs to a group of people from whom he needs money than there is to a group from whom he needs votes. The difference is in expectations and context: donors want to feel like they have the inside scoop on what's happening and donors are fine with turning off the cameras. Which means that candidates' pitches can be more virulent, even if they're no more accurate.

Understanding modern politics means recognizing both that candidates will talk up their positions that are popular and talk around their positions which are not. It means understanding that how they do that shifts, depending on audience. But most of all, it means recognizing that you're being played by the candidates, that who you see running for office is a hologram created mostly by the candidate and his or her opponent.

Let's have Tom Friedman serve as an example. A few weeks ago, he wrote this of Romney:

I know Romney doesn’t believe a word he’s saying on foreign policy and that it’s all aimed at ginning up votes: there’s some China-bashing to help in the Midwest, some Arab-bashing to win over the Jews, some Russia-bashing (our “No. 1 geopolitical foe”) to bring in the Polish vote, plus a dash of testosterone to keep the neocons off his back.

"I know Romney doesn't believe a word he's saying." How? How can anyone, besides Mitt Romney, feel 100 percent confident in knowing how President Romney will act once in office? Had you asked Tom Friedman in 2006 what a President Romney would do about healthcare, he probably wouldn't have answered: he'll repeal federal legislation based on what he accomplished in Massachusetts. Tom Friedman is confident in the vision he has created of what candidate Romney stands for -- which means that candidate Romney has done his job well.

Romney is also taking advantage of a shift in the relationship between the candidate, the press, and the media. Since the 1950s, campaigns have had increasingly sophisticated tools for contacting voters directly. Television ads, direct mail, phone banking, social media. Candidates no longer need to rely on the press to translate a message to the voter -- the campaign can tell the voter itself. And without a filter, the message can be much more finely crafted. A voter of a certain age and income on a certain block can see a piece of mail in the afternoon that's echoed in a TV ad two hours later, just as the campaign predicted. Of course the campaign isn't going to let fact-checkers dictate the campaign -- they aren't going to let the press interfere with the message at all. The press, a campaign will argue, is if anything there to point at the message as it drifts by, not to stand in its way.

When asked about the "47 percent" comments at his hasty press conference, Romney took issue with the idea that he'd said anything wrong. "You said a number of things there, and the answer is that I'm talking about a political process of drawing people into my campaign." That's the answer. The answer to a question about what he meant by his comments is that he's drawing people into his campaign.

Candidates suck up to you so that they can lie to you. It doesn't matter how much money you give, it doesn't matter how much they need your vote, it doesn't matter if you write for the New York Times. A candidate will say whatever he thinks you need to hear -- even, sometimes, if it directly contradicts things he's said in the past. It's a tangled web which sometimes, as Romney keeps finding out, gets torn.

There's only one sure-fire way to see what a candidate will do in office. Elect him.