YOU MIGHT BE be excused for concluding, when you read the latest article describing how men voted for this candidate and women for that one, that all of the men in this country are lined up on one side of the political battlefield and all the women on the other. But when the politicians talk about a gender gap, what they're talking about are statistical differences: in the 1980 election, for example, women preferred Ronald Reagan over Jimmy Carter by a narrow 47-44 percent margin, while men gave Mr. Reagan a landslide 55-37 margin. In a country where elections are usually decided by narrow margins, that's a big difference. It's similar in magnitude to the difference between white-collar and blue- collar voters in that election, for example.

Will this "gender gap" become a permanent part of American politics? Probably not: there's nothing really permanent about political divisions. The gender gap itself has changed just in the few years since analysts started noticing it. In 1980 many women were reluctant to vote for Ronald Reagan because they feared that he, as a little-known challenger disposed to aggressive talk, might be more likely to get us into war than would Jimmy Carter, who was by then a known quantity. Historically, women have been less inclined than men to take chances on turning out incumbent parties that have kept the peace. But today Mr. Reagan is a known quantity too, and for all the criticism he has received on foreign policy issues, the polling evidence suggests that women are now not much more likely than men to see him as a threat to peace.

The gender gap that exists today seems to result more from responses to economic and cultural issues. Women, particularly those who are unmarried and those who are the heads of single-parent families, have been affected much more than men by Reagan administration cuts in domestic programs. They are the constituency for childhood nutrition and school-lunch programs--a constituency that may not be represented by many lobbyists on Capitol Hill but that turns out to include a significant number of voters. Many women who are not traditional housewives seem also to take umbrage at the president's attitudes on various cultural and social issues.

Note that women have not reacted differently from men just on so-called "women's issues." Their differences include a broad range of foreign and domestic issues in which voters of all kinds have an interest. No one is entirely sure why. The poor politicians keep scurrying around, trying to keep in touch with voters in a nation that seems to be changing faster than they can handle.