The last Obama-McCain debate tonight – and yes, you do have to watch, and besides there’s no point in quitting just before the end of the marathon – can remind you of the actual great debates in American history.

They did not involve 90-second answers with 30-second follow-ups, or questions from the audience, or painstakingly negotiated seat arrangements, or carefully vetted moderators, or fixed camera angles, or even candidates for president.

The Lincoln-Douglas debates, in the 1858 Illinois race for U.S. Senate, were completely inaudible beyond the range of the candidates’ voices, and there were no cool questions sent in through YouTube and no practice debate with the tallest Democrat that Douglas could find pretending to be Lincoln.

But the debates turned out pretty well. Two years later, both the candidates became their parties’ nominees for president.

After two 2008 debates, it seems likely that if John McCain and Barack Obama weren’t already their parties’ nominees for president, these debates wouldn’t have helped their chances.

And, of course, we think all the wrong things are the problems.

We want the candidates to be more spontaneous, to interact with each other, to abandon their talking points, and to do a lot of other things that would be important in a trust exercise in a summer camp, but may not be that useful in choosing a president.

So in the first debate, moderator Jim Lehrer keeps telling the candidates to talk to each other, not to the camera – in other words, to forget everything that got them this far – and in the second debate moderator Tom Brokaw keeps fretting that they’re talking too long and violating the rules.

The real complaint isn’t that the debates aren’t telling us something useful. We’re complaining that they’re committing a far more serious sin: they’re not good television.

The Lincoln-Douglas debates might have been terrible television. They were three hours long, with one hourlong opening, the second candidate responding for an hour and a half, and the first candidate finishing for half an hour.

Nobody told Lincoln to speak directly to Douglas, no yellow lights went on to warn Douglas he was nearing the end of his 90 seconds.

But at the end of the debates, people knew how the two of them felt about the future of slavery and the future of the country. Possibly that would have been harder for Lincoln or Douglas to manage in 90 seconds, even with a 30-second follow-up.

Ninety seconds is just about the right amount of time to discuss whether Barack Obama spends his spare time making Molotov cocktails with terrorists from his neighborhood, or whether John McCain still thinks picking Sarah Palin for a running mate was his best idea ever. It may not be quite enough to explain how a candidate plans to deal with the collapse of the Western world’s financial system.

Even if he’s looking directly at the other candidate when he says it.

In a time when the lengths of our attention spans have required the invention of the word “nanosecond,” nobody thinks Americans would actually listen to an hourlong opening statement. And besides, most of the time the candidates we’re listening to are not exactly Lincoln.

But when we say we want the debates to tell us what the candidates would do, that’s not quite true. What we want is one candidate to tell the other that he’s no Jack Kennedy, or make a really good joke, or get really angry.

Nobody says that, of course. Undecided voters, interviewed before and after debates, know enough to look thoughtful and say they want to hear more about the candidates’ plans. They insist on that, even though the 2008 campaign has been going on pretty much since the Lincoln-Douglas debates, and not even the candidates’ immediate families really want to hear more from them.

A century and a half later, after television, the Internet, tracking polls and 24-hour cable news channels, we’re in an entirely different situation than when Lincoln ran against Douglas. But one thing has clearly not changed:

We get the debates we deserve.