FEW SUBJECTS generate more hypocrisy in election campaigns than debates and debating. In the first place, most of the debates aren't debates anyway, but rather joint press conferences and seriatim expressions of harmless views on stately subjects. Probably, we shouldn't say "first place," however, because by the time you finally get around to the debate itself, you have been through a separate campaign of jockeying, negotiating, grandstanding and invective that is, frankly, often more entertaining and instructive than the modest event which at long last occurs.

In Des Moines, the Republicans rather violated precedent in all this: they put on an interesting and pretty useful show. Last week in Manchester, they were a little less compelling. By Saturday night in Nashua, the old (bipartisan) tradition has reasserted itself. We are alluding to the old tradition of the empty chair, the raised voice, the locked door, the you-did-not/I-did-too. I'm-here-but-he's-chicken display -- all or most of which the Republican traveling show treated the public to. Out of our abiding respect for your santiy and the claims on your time in a busy city, we are not going to try to recapitulate the strange and complicated route by which a regulated and reformed (in law, if not in spirit) electoral process brought Messrs. Reagan and Bush to the scene of a two-person debate presided over by the editor of the Nashua Telegraph and paid for by Mr. Reagan (who saw fit, and properly so, to refer to this fact when the aforementioned editor tried to cut off his microphone). We will only tell you that the circumstances are believed by all the best people to represent the new, improved democracy.

However, the old political demons managed to sneak in nonetheless. The Nashua Four -- i.e., candidates Baker, Dole, Crane and Anderson -- who had originally been left out of the program and who protested were informed that Mr. Reagan, the bankroller of the event, would let them participate. Mr. Bush balked and, worse, balked in an unseemly, unbecoming, unmagnanimous way. It was politically dumb and nervous-looking and it invited what he got. Sen. Baker called the close-out "the rawest political act I've seen in 15 years" of politics. Sen. Dole said this was "the sorriest episode in American politics." And Rep. Anderson, for once not loath to agree with his fellow office-seekers, said, "George Bush shot himself in the leg."

Sometimes episodes like these pass. Sometimes they are the lucky (or unlucky, depending on which participant you are) moments that alter voter perceptions dramatically and change the whole course of a campaign. It will not have escaped your malevolent attention that Gov. Reagan, who lost Brownie points for having shunned the Iowa debate, has now picked up points for his apparent effort to let at least six Republican flowers bloom to Nashua. He is also said to have scored some points by appearing authentically angry and willing to say so -- authentic anything being in such short supply in these contests. Mr. Bush, presumably believing he may have encountered one of those mements and made the worst of it, apologized to his colleagues in a letter yesterday. Today's returns will tell us whether that was 1) needed 2) not needed 3) too late. The only thing of which you can be certain is that whereas the "debate issue" may conceivably have eliminated a candidate, the "debate issue" itself will linger on . . . and on . . . and on.