THE THING about the now-vaunted "war and peace" issue is this: there isn't one. Or at least there isn't one in the sense that it's being actively cultivated by the Carter administration. The alternative to Jimmy Carter is not nuclear holocaust. The alternative is another candidate of another party with a different idea of how to maintain and strengthen an international system that, while it never can be taken for granted, has shown an undeniable sturdiness over the nuclear years.

Mr. Carter's idea is to combine military preparedness with a readiness to reduce friction points. Gov. Reagan's emphasis is on building up strength the better to deter and avoid challenges, not merely to be able to handle those that come along. You do not have to accept the Carter frenzy to wonder whether Mr. Reagan might not be too slow to seek out accommodations. At the same time, it is necessary to ask of Mr. Carter whether the Soviet Union and other would-be disturbers of the international peace may not mistake American moderation for weakness. Either way, crisis could ensue, and this is the point on which the real argument -- as distinct from the campaign yelling -- turns.

Neither candidate is for war, both would seek peace. But peace is something other than a tense and edgy silence between ever more murderously armed states. And it is also something other than so thoroughgoing an eagerness to avoid conflict of any kind that a country will let its genuine interests be eroded to the point where it is more likely to be drawn into a conflict it cannot control.

When Secretary of Defense Brown said the other day that the presidential election was going to be a referendum on the SALT II treaty, he was off the mark in several ways. It's not just that this formulation makes you wonder whether the Carter administration has written off the support of anti-SALT II Democrats like Sen. Henry Jackson of Washington. It's equally that SALT II is flawed as a touchstone war-and-peace issue in this campaign. That is because many Democrats whom the Carter administration would hardly accuse of being "warlike" have serious reservations about the treaty, and the administration knows as well as anyone that the president's call for the Senate to take up the treaty, soon after what he hopes will be his reelection, Afghanistan or no, offers no assurance that the treaty will pass.

Mr. Reagan, meanwhile, urges scrapping SALT II and negotiating another treaty, "not simply [letting] the Soviets race ahead." Why he thinks the Soviets would be willing to negotiate another treaty, on his terms, is a mystery. He has enlisted Henry Kissinger and a clutch of other GOP foreign policy notables to endorse his views, or rather their shaded versions of his views, but we still can't say we find them any more plausible than the general argument on defense policy that has marred this campaign.

Still, there is the SALT II treaty, languishing half-supported and half-dead in the Senate. If Gov. Reagan, upon election, is to jettison it, then he needs to make a more plausible case than he has made so far for another, balanced policy for dealing with Soviet power. If a reelected President Carter is to succeed in reviving it -- and we think there is no sensible alternative to ratifying a treaty that, for all its limitations, represents an essential continuity of the arms-control side of Soviet-American relations -- then he will have to show a more realistic assessment of Soviet power than has been evident in his first term.