Instant analysis -- the corn meal of our time, the basic staple of a heavy media diet -- produced mostly mush after Sunday night's not-quite-great debate in Baltimore.

This mannerly forensic minuet involving John B. Anderson and Ronald Reagan didn't lend itself to sharp judgments. The instant analysts thrive when the event in question offers an obvious target -- for instance, Gerald Ford's mid-debate, unilateral declaration of Polish independence. Sunday's debate created no targets, leaving the analysts baffled, or at least waffled.

Nobody lost, according to the morning-after line -- well, nobody except perhaps President Carter. But he might have lost worse if he'd been there. The two who took part both did a dandy job -- on that there is broad agreement.

On NBC's wrapup Sunday night, Tom Brokaw declared the debate "a dead heat," to which anchorman John Chancellor responded: "That seems to be the consensus." Who won? "We're in the wrong place to answer that," replied CBS' Bruce Morton, who watched the debate from the seats in Baltimore convention center. "I think you have to have been in somebody's living room to see how this played," Morton added.

The living rooms will be heard from later. According to the first available statistics, the television audience Sunday night probably included 40 million to 50 million Americans. The figures so far only cover New York, Chicago and Los Angeles, where about 42 percent of the households tuned into NBC or CBS, the networks that carried the debate live. But what did those millions see? And how long did they stay tuned -- or awake?

Some of the instant analysts suggested that this encounter was less than compelling television. "A rather emotionless debate," said Ted Koppel at ABC. "It wasn't a strikingly dramatic debate, to say the least," observed Richard Scammon on NBC.

There is a curious aspect to media treatment of media events; it is almost inevitably respectful, serious. The idea that perhaps this debate won't have much impact on the course of the election campaign got no ink or air time at all. Instead the question was, which way would the impact run?

If history is a guide, the ultimate judgment on Sunday night's debate will come not simply from the scientific evidence that polls and, ultimately, the election results provide, but also from the conventional wisdom that takes shape in the days ahead. But the instant analysis and morning-after assessment of this event raise the possibility that no conventional wisdom will emerge at all -- that the debate had too many round edges and involved too much political ambiguity to leave any clear impression.

Jack Germond of The Washington Star was the only commentator to take a stark position on the morning after. According to Germond, "the one thing that is clear is that President Carter lost." By Germond's reckoning, both Reagan and Anderson did well enough to impress voters, whereas Carter -- well, by the last paragraph of his analysis, Germond seemed a little unsure about Carter: "The president might have suffered more political harm by showing up here, just as he and his managers feared. But he was the only one of the three who won nothing in Baltimore . . . "

The two written analyses of the debate that probably reached the most readers yesterday were by Walter R. Mears and Clay F. Richards the political writers for Associated Press and United Press International respectively. Both wrote cautious assessments, Mears declaring that this particular prime time spectacle is "going to wind up among the reruns" unless a new star is added to the cast -- Jimmy Carter.

Both wire service analysts agreed on one point which the UPI's Richards put like this:

"Carter's decision to sit out the first debate seems to have paid off politically for the White House. At least it does not appear to have done Carter any real serious damage -- while participation could have."

Mears wrote it this way:

"Absentee Carter ran the biggest gamble, wagering that staying away would hurt him less than participating and further enhancing Anderson's stature. He seems to have won that bet -- at least no serious damage was evident Sunday night."

John Chancellor said about the same thing to NBC's late-night, post-debate audience Sunday. "I think he got away with it here tonight," Chancellor said of the president.

The onlly purportedly objective analysis of the debate came from a panel of professors -- of forensics, mostly -- assembled by AP. Six of the seven judges thought Anderson had beaten Reagan in purely debating terms; the seventh called it a draw. Tom Pettit of NBC News said on the Today show that it wasn't a debate at all -- that the League of Women Voters' format had been "lousy."

We'll never know with any confidence how the messages sent out of Baltimore Sunday will infect voters' minds. For one thing, those messages didn't arrive in an uncluttered state -- in the age of media glut, the consumers are always overloaded.

Reagan's campaign made a clever attempt to contribute to the overload Sunday and yesterday, buying a dozen expensive prime time advertising spots for a new commerical. The ad showed an empty lecturer's lectern while a female voice read this message:

"The League of Women Voters invited President Carter to join in the 1980 debates. He refused the invitation. Maybe it's because during his administration inflation has gone as high as 18 percent. The number of Americans out of work has reached 8 1/2 million. Housing starts have hit a new low, while interest rates have hit a new high. Maybe he won't debate because he knows the real question is, Can we afford four more years of this? The time is now for strong leadership. Reagan for President."