AS THE NATIONAL DEBATE surrounding the Great Debates intensifies, the most debatable issue of all has gone virtually uncontested.

Party politicos have argued that the Democrats and Republicans should run the quadrennial events; the League of Women Voters defends its track record as the debates' sponsor and will leave the arena kicking and screaming, if at all.

But both sides gloss over the underlying question: whether the presidential debates are worth perpetuating, or what they really prove.

Since their inception in 1960, the debates have grown to epitomize the excesses and shortcomings of modern presidential electioneering. The term "debate" itself has become a misnomer. A panel of interrogators ostensibly steers the discussion, but in practice, their questions serve as little more than cues for the candidates to launch into carefully rehearsed speeches and scripted snippets of humor.

BEFORE TENS OF MILLIONS of viewers, the nominees for what is arguably the world's most powerful office bask in the penetrating glare of studio lights, and the most telegenic candidate wins the day. The debates have proven to be more of a screen test than a test of the contenders' ideas and qualifications. The candidate who delivers the best performance lands the leading role.

Reporters and commentators rush to file colorful accounts and declare a victor. The medium encourages these ringside judges to base their scoring on poise, appearance, tone, and rhetorical coups. According to the traditional scorecard, the candidates' make-up men and wardrobe consultants generally prove more critical than their policy advisers.

It is a telling commentary on the debates that past match-ups have hinged on the trivial, the superficial, or the spectacular if momentary mental breakdown. And because of all the attention focused on the Great Debates, these factors are magnified beyond any reasonable proportion.

VIEWERS OF THE FIRST 1960 debate between Richard M. Nixon and John F. Kennedy '40 remember most vividly Nixon's brooding, perspiring visage, his dark, shifty eyes, and his shadowy beard growth, all of which stood in contrast to Kennedy's composed image.

Incumbent Gerald R. Ford's patently absurd description of Poland as a free and independent state dominated press coverage of the 1976 debates. Ford's remark was a classic example of the kind of epic mental lapse that the debates' set the stage for and award top billing.

Four years later, Jimmy Carter subjected himself to ridicule by gratuitously invoking his eighth-grade daughter, Amy. Amy considered nuclear proliferation the most burning issue of the day, Carter said, and the voters laughed.

And most recently, President Reagan almost lost a seemingly insurmountable lead over challenger Walter Mondale when he fell apart on live television. An incoherent, mumbling, lumbling Reagan left Americans wondering, had their amiable but aged president lost his marbles?

But if Reagan's dismal (and revealing) round one performance was disturbing, the case with which he regained his good standing was nothing less than horrifying. Despite an otherwise mediocre performance riddled with factual errors and lesser mental lapses, the president redeemed himself with a single one-liner in the second debate.

"I will not make age an issue. I will not take advantage of my opponent's youth and inexperience." Reagan said, and his reelection was sealed.

Then again, perhaps it is only fitting that the climactic event of the presidential campaign raises to new heights the supremacy of style over substance.