The presidential campaign will inevitably bring a revival of the bad idea that all candidates should submit to independent medical examinations, the results of which would be made public. The often-cited rationale for this proposal is that Franklin Roosevelt's failing health was concealed from the voters when he ran for a fourth term in 1944 - and that if it had been publicly known that he was going to die within a few months of his re-election, he might not have been renominated and surely would not have been re-elected. Also argued in support of mandatory examinations and public disclosure is that John F. Kennedy dissembled about the fact that he suffered either from Addison's disease - an adrenal disorder - or something resembling that affliction, but that whatever it was, he was on potent medication, the side effects of which might be uncertain.

Perhaps because of these two presidential health experiences - plus Eisenhower's and Johnson's illnesses while in office - it has become customary for candidates to submit to some sort of physical examination. Invariably, however, they emerge from the clinic with a report that suggests extraordinary hardness and immunity to the wear and tear that afflict ordinary people. Since the doctors who examined them are bound by the rule of physician-patient confidentially, who's to know if the candidate's version of his health report is the full story? It's that possibility of concealment that inspires the quadrennial interest in independent and mandatory examination and disclosure.

This extension of truth in packaging to presidential candidates has its attractions, but the difficulty is that it asks more of medicine than medicine can reliably provide, while raising possibilities for campaign mischief-making that our already muddled election process can nicely forego.

First, there is little that medicine can infer from present physical condition about potential presidential performance. It can tell us, in the mass, how many people with a given physical condition will survive over various periods, but it can't tell us which ones; nor can anything be inferred from the absence of dangerous symptoms, except that at the time of examination, they were absent. As for questions of stamina and judgment under stress - qualities that are frequently cited in support of medical candor - it is doubtful that any physical examinationa could be as revealing as the rigors of the modern presidential campaign. The concealment of Roosevelt's condition occurred pre-TV and with his infrequent public appearances attributed to the demans of wartime leadership; there is no chance now of a candidate hiding out like that without arousing vote-losing skepticism.

It will be argued, however, that if a candidate is afflicted with a potentially serious medical problem, the voters ought to know about its, so that they can decide for themselves. The trouble with that idea is that, apart from seriously disabling illnesses, which would be difficult to hide, medical information is useless for predicting how a president might behave in office, but it could be used for sowing a lot of campaign confusion. High blood pressure, cardiac history, diabetes, respiratory problems, arthritis, asthma and so on down the list of physical impairments not uncommon in the presidential age range: What in the world is the voter to make of such information, given that any or all of these afflictions can be found among people who function effectively in difficult circumstances. The reality, of course, is that they signify nothing of consequence to the sought-after office. But, if the candidates' medical charts go public - instead of existing, as they now do, under a voluntary, controlled-release, gentlemen's agreement system - the temptation to exploit the other guy's aches, pains, ailments and medications is likely to prove too much for eager office-seekers.

Just behind the calls for telling all about the candidates' physical condition are occasional but serious suggestions for reports on their mental condition. Since none of them would sit still for such an examination, that's simply not going to happen - which is just as well, in view of the current state of intellectual disorder and strife in the so-called mental-health profession. But even assuming that some yardsticks could be agreed upon, if it were found, for example, that a presidential candidate was afflicted by delusions of grandeur, the only sensible reaction would be, "Well, of course."

The interest in bringing the medical sciences into presidential selection, as into so many other aspects of American life, is characteristic of a yearning for certainty on matters that can never be certain. The measure of presidential potential is in character, judgment, values and experience. Science has no meters for those qualities.