Practically cheek by jowl last Sunday, one could read in two leading newspaper columns virtually identical assertions that 1) liberal moles in the State Department had tried to undercut the president's missile negotiation by leaking word that he had prepared a fallback position and 2) the administration has no fallback position.

Shocking, wasn't it? Here were distinguished journalists--men who themselves scrupulously source everything they write and who have never savaged a president with a leak--revealing that in this town there are actually bureaucrats so unprincipled as to try to subvert a president's plan. This assumes, by the way, that the columns were correct on the facts.

But it was more disturbing--and this is for real--to be told that the president has embarked on a major negotiation without a fallback position. Could this be true of Ronald Reagan, a man who, to get to Geneva, discreetly dispensed with several decades' accumulation of baggage about "linkage," the Kremlin's indecency as a negotiating partner, and the rest?

Those who say Reagan made strictly a take-it-or-leave-it offer are engaged, I think, not in reporting or analysis but in cheerleading.

Reagan himself said in his big speech of Nov. 18, after all, that he would "listen to and consider the proposals of our Soviet counterparts." Pressed on the point on television on Sunday, his chief lieutenants dodged in the manner of mature people who realize that you don't open a negotiation by going public with a fallback but neither do you pretend you don't have one.

Actually, it might comfort Soviet hawks to hear that Reagan will not "listen." It would confirm him as precisely the leaden zealot portrayed by their hostile propaganda. It could persuade the Kremlin to hold fast in its own opening position, confident that sooner or later the bottom would drop out of Europe and Reagan would be left holding an empty bag.

There have been too few leaks to provide a full picture of how the administration came to the position Reagan announced. But my surmise is that a Pentagon propensity for deep cuts met a State Department awareness that a dramatic peace proposal was needed to arrest Europe's slide toward neutralism.

For this administration, preoccupied by the specter of Soviet strategic ascendancy, it could not have been hard to propose deep Soviet cuts. Its real achievement was to treat with sensitivity European political currents that many Reaganites might have preferred simply to denounce. A triumph of the Pentagon over the State Department? How about a blending of two bureaucratic perspectives?

To nurse a fallback position, to be sure, puts a heavy burden on negotiators. They must determine when to hold and when and how to bend. And here we come to what will remain a mystery until the president is tested in the crucible of Geneva.

President Reagan came to power insisting that the missing element in the security equation was not so much power as will, which he promised first to personify and then to mobilize.

Liberals fear the president will personify the national will so rigidly that he will miss opportunities for the timely concessions essential to the success of any talks. Conservatives darkly suspect that the public lacks spine; this leaves it to the president to fill with his will the whole space that the national will might otherwise occupy.

This negotiation involves in the first instance a judgment on Europe. Liberals, considering Europe a worthy partner, see a fallback position as a card to be played early, to keep Europe in the game; to them the game is an open-admission free-for-all. Conservatives, perceiving Europe deep down as unworthy, see a fallback as a card to be played late, if at all, to keep Europe out of the game; to them the game comes down to a great-power one-on-one.

Where is Ronald Reagan? The image of him that teases my mind is that of a man with a potential to confound the familiar judgments of both friends and foes. I am looking for him to do something, in this negotiation, that will surprise almost everyone.