Does anything happen off camera?

Now that the petty matters have been settled - inflation, foreign policy, national defense - the Senate is about to get down to the serious business of debating whether it should permit itself to be televised.

Sen. Howard H. Baker Jr. is all for it. And why not? The cameras of Watergate made him a star, teaching him to respect Nielsen ratings almost as much as voters from Tennessee. The House of Representatives has allowed itself to be televised since the spring of 1979, and Senator Baker warns colleagues who think Variety is the spice of life and not a show-biz paper: ''If we don't get television in the Senate in a decade or less, the House will be the dominant partner in the congressional branch.''

To a senator with get-up-and-go, this prospect should be even more alarming than falling behind the Soviets in the arms race. But, curiously, there are shy chaps who just don't get the point. Sen. Russell Long of Louisiana has expressed concern that the presence of lights, cameras, and mike booms might make senators even ''more verbose'' and inclined to ''play the prima donna.''

Senator Baker thought a moment and then found the answer. ''It's hard to conceive of any of us becoming more verbose,'' he countered. ''All of us are prima donnas.''

As a veteran artist in the medium, Senator Baker went on to explain that television is a ''quiet and intimate'' medium. Oratory would not come off well, he reassures the rhetoric-sufferers. Styles ought to turn toward the less rather than the more flamboyant - after the manner of Abraham Lincoln rather than Daniel Webster, one is free to assume.

In fact, Senator Baker trots out the familiar myth that television is the honest person's medium. The lens just sees right through the phony.

If only judgment of character were that simple!

Senator Baker can count our vote as undecided. We aren't really worried that the continued absence of a coaxial cable will upset the American political system of checks and balances, as Senator Baker fears, citing the picture-tube power of the White House as well as the House. But, as always, we wonder what subtle and unpredictable effects the presence of a camera will have on the behavior of people facing it.

Give Narcissus a pool, and he becomes a different man.

What would George Wshington have said, you ask, or Benjamin Franklin or Thomas Jefferson? Senator Baker believes he knows the answer: ''I think that had radio and television existed at the time of the framing of the Constitution and the design of our structure of government by our founding fathers that they would have included electronic access as well as personal access to the public galleries.''

We are not so sure. Maybe Franklin could not have resisted a new gadget. But Jefferson? He conspicuously lacked the wish to turn politics into drama; he was always hoping to make it a branch of philosophy.

And speaking of public galleries, we must ask, only half-joking, whether a new breed of fan will show up there, mouthing ''Hi, mom!'' and waving a finger to signify ''We're number one'' whenever a camera is pointing. Worse, will torn sheets be unfurled, reading, ''Peoria loves CBS and Dan Rather''?

If you find this possibility far-fetched, watch any sports event for its camera-consequences on participants, officials, and spectators. People in front of cameras have an awful tendency to become actors. They mug. They hug. They perform.

We aren't saying that focusing a camera on the Senate will turn it into a sitcom - ''One Hundred's a Crowd'' or ''Capitol Hill Blues.'' But even without cameras, ''all the world's a stage.'' Do we need to turn it into a sound-stage, all wired up? First the Senate, then the courtroom, and then? We are already into the era when we film documentaries about the filming of documentaries. In a few years where in the world will we go to find an untelevised event?