After Dallas

The Republicans leave Dallas flush with confidence about the fall campaign, proud of their standard-bearer, Ronald Reagan. For campaign '84, they have joined the Democrats in setting up a classic political contrast: The Democrats left San Francisco stressing the theme of ''family'' - suggesting a widening network as change alters the traditional family; a more inclusive concept of government; looking to the needs and aspirations of women, blacks, Hispanics; not excluding gays. The Republicans exit Dallas emphasizing individual achievement, entrepreneurism, national pride, and a more traditional concept of family, less accommodating to changing social mores and diversity in life styles.

Implicit are the contrasting American political themes of equality vs. liberty: the Democrats concerned that government should spread opportunity more widely, the Republicans contending that less government will permit individuals to achieve their potential more fully.

There is always a tension between these two tendencies in American politics. Wings of each party overlap to share the concerns of the other. Many Southerners and Westerners who are nominally Democrats agree with the Republicans in their attitudes toward government intrusiveness. Many Republicans object to the 1984 GOP party platform's ironic support for government intrusion in individual decision in areas such as school prayer and abortion.

Both parties have tried to emulate the other's 1984 advantages. The Democrats , especially Gary Hart, asserted they were the party of ideas. It has really been the Republicans, however, especially among the GOP minority in the House, who have been the political firebrands of late. The Republicans have displayed one woman after another on the dais this week, including the First Lady, but the Democrats have the litmus-test women's planks in their platform and the first woman nominee.

The Republicans have the best of the economic issue in 1984. Prosperity does a lot for one's sense of well-being. The deficit gives the Democrats a tactical opening, if they can exploit it in debate about tax increases.

The two dynamic personalities to emerge from the conventions are Geraldine Ferraro and Ronald Reagan. Perhaps Ms. Ferraro should debate the President, and Walter Mondale debate George Bush, as the first stage in a forensic round robin. Now that would be fun.

The Republicans' evident affection for their nominee, the healthy economy, and the fact that Mr. Reagan's career will run out whether or not he wins a second term, all worked together to create two conditions in Dallas: a great deal of uninhibited self-merchandising by aspirants for 1988, and a realization that another ideological battle within the party will have to be waged among Reagan's successors.

Already a move is on to declare that if Mr. Reagan wins in a landslide, it will not mean a mandate for the party platform. The public relates personally to the President, not to his policies, say those unhappy with the sharp ideological tilt in the GOP platform. Those who like the platform will of course claim the opposite: that a one-sided outcome in the presidential race will constitute a mandate for the platform.

Some Republicans were troubled by what they saw as an American self-preoccupation this week in Dallas. Isolationism may be too strong a word; but they felt Americans were being encouraged to neglect the needs of developing countries while Americans got on with their own success.

The Democrats seemed to be saying: We're not all entrepreneurs; we need teachers and unions and government working to improve the opportunity of society as an extended family. The Republicans have a different vision. They are saying theirs is a party moved by ideas. It is the party of the future. They feel the baby-boomer generation will respond to the Republican vision - confidence in America and the entrepreneurial spirit.

As Paul Trible, the young Virginia senator, puts it: ''We want to achieve. We want to leave our mark. Republicans are speaking to that sense of vitality that attracts the young.''

Of course, for most voters the election will come down to a choice between two individuals: Walter Mondale and Ronald Reagan. But the parties are already looking beyond these two figures to new leadership in the longer-running contest between ''liberty'' and ''equality.''