AT THE BEGINNING of this year's election compaigns, the question of Ronald Reagan's age was openly and often mentioned, and as often as not was hotly debated. Today one would think that the issue had been resolved, and that the verdict had been pronounced in his favor. Anyone who raises sharply the fact that old age is closing rapidly on him is made to feel a like gauche.

This seems to happen more and more in the primary campaigns. As the process of nominating a candidate goes on its long and cumbersom way, the question of a canidate's fitness to be president is submerged by the more immediate question of his ability to survive the primary ordeal, the qualities needed for the one being very different those required for the second. The all-important question of presidential capacity is postponed to the general election, when it is of course too late for either of the parties to change its nominee.

One would have thought that the closer that Reagan draws to the nomination, the more piercing and controversial the question of his age becomes, but in fact this is the very opposite of what happens in the present system. It is assumed that his victories prove that he is not too old to be his party's candidate, and whether he is nonetheless too old to be president is put aside to be decided at a later date.

In accordance with their traditional impulse not to kick a man when he is up, even the most unexpected Americans are today anxious to show that they can be amiable about Ronald Reagan. I am one of those who cannot join them in this exercise in forbearance. He seems to me today to be as banal a figure as ever to be considered as leader of the free world, and I have no doubt that many of his policies would hurt and neglect those whom his politics ought to protect and succor. His age is by no means my only objection to him.

But how can anyone deny that his age is a legitmate issue in this election? That is one side of the question. And how can the new forbearance of him obscure the fact that his age is a disquailication? That is the second side of the issue.

Let us first be rid of the sillier comparisons with figures from the past. Yes -- oh, yes! -- Winston Churchill remained in office during the Second World War past the age of 70. But the British people then bundled him out of power at the first opportunity, and even before the war against Japan had been won, so what conclusion (on way or the other) could one draw from that? Yes -- oh, yes! -- he was then returned to office when he was almost past the age of 77, and did not finally resign (and then only with great reluctance) unitl he was already an octogenarian. But it is not until now that I have ever heard Churchill's second ministry put forward as a model for our emulation.

The accounts from his ministerial colleagues at the time were hilarious, and would have been alarming if they had not done much of the government for him. One of the reasons whey the memoirs of his doctor, Lord Moran, caused such a scandal was that they presented, in detail and mercilessly, so gross a picture of senility in office.

The final years of Charles de Gaulle in power were no more reassuring. It does not matter to what example one looks -- Konrad Adenauer is obviously another -- old age in power is always troubling. It is a time of interregnum -- even if the old man has just taken power -- and of uncertainity about the future. It is always a period of stubbornness at the top -- old men are not easily moved -- and of restlessness in those meant to serve him, as they prepare to profit from the succession.

There is less lovalty in the administrations of old men than in any other, less disposition to cooperate and make plans with the intention of executing them. Dicators almost always cling to power beyond the time of their usefulness, and the memoirs of their regimes tell vividly of the atmosphere of dissolution and personal hostilities.

It is the same whenever an old man holds the reins. But at least when one speaks of a Churchill or a De Gaulle or an Adenauer, one is talking of men who have held and may still hold the reins, and who merely believe that power should be continued on to them as longs as it is their fancy. The people are willing to reelect him because he is at least a known quantity -- "the CHIEF," "The old boy," Winnie" -- and his colleagues are used to serving him and to circumventing his mischiefs.

"Old Men Forget" was the title which David Duff Copper gave to his political memoirs -- perhaps one of the 30 greatest political autobiographs in any language -- and one thing which old men forget to do is to resign. It is usually easier to allow them to stay on than to get out the hatchets to dispose of them. But what is one to make of an old man who actually wants to hold the highest office for the first time?

We often overlook the fact that very few men or women wish and set out to be president or prime minister. Think back to your class in high school or college, and you will be hard put to remember one who ever entertained such an ambition. Log cabins are simply not populated with children who wish to make it the White House. Rail-splitters would usually prefer to be chairman of the railroad company than president of the United States.

One in fact has to be rather odd to want to be president at all. One must be that much odder to pursue the presidency for the first time at an age when one could retire with contentment and honor.

Those who want to get to the top of the greasy pole, as Disraeli called it, must be prepared to claw and clamber to keep their place on it. There is nothing honorific in the possession of great power. It is a merciless occupation, often for 24 hours a day, with doubtful rewards. To rule is not the same as to reign, and when to reign also meant to rule, there was not much enjoyment or reward in it either.

The old man who wants the highest office for the first time is hoping to reign. He wants an Oscar bestowed on him, not for his talents in his profession, for he has won none for those, but simply for being around a long time. He wants it for true grit. He wants to be crowned and enthroned, and then to make progresses through his realm.

This is exactly how Ronald Reagan has sought the presidency -- the "eleventh commandmant" is the plea of a man who wishes to be crowned by acclamation and not elected in a political rough-and-tumble -- and it is the most ominous consequence of his age. It means that yet again an attempt will be made to govern as if the presidency is not a political office.The need for vital political decisiions will again be obscured by the effort to reign by amiable royal proclamations. Neither America nor the free world can afford yet another presidency which tries to escape the hardness of political decisions.

To this muddled old man's view of politics will be added the usual stubbornness of old men when they hold the highest office. He will not rule; neither will he resign.He will merely try to reign by substitutes for the royal touch.

The hard business of hammering out and forging new instruments of power, which will survive the president's term of office and fit the political needs of a new generation, which is the most important business to which a politician can attend, will again be postponed, as it has been in America for 40 years. Ronald Reagan in his old age does not promise to rule the nation but to sancitify it, and Americans will discover too late that they elected only a shroud from which the image has faded.

They do not fear that Reagan will take America into an unnecessary war. That is not the way of old men. I fear America will become what in effect like forests, because the people have finally been made to supine to need even them.