NEWS ANALYSIS : First Step to European Unity: Deciding What It Means : Diplomacy: EC nations want to form a single political body. They are still sparring over its strength and structure.

At last weekend’s European Community summit meeting here, the leaders of the 12 member states agreed to seek a singular definition of a contentious concept: political union among their states.

But that is easier said than done, for as a diplomat dryly commented, “The trouble with political union is that there are dozens of definitions of what it means.”

Indeed, West German Chancellor Helmut Kohl and French President Francois Mitterrand, who lead the drive for an unprecedented and ambitious political union, have never in their various statements on the subject clearly defined the term.

In broad terms, the West Germans want to strengthen the European Parliament in Strasbourg while the French want to see the powers of the EC’s central executives in Brussels increased.

So the main thing that has emerged from the long discussions of political union is that it means different things to different national leaders.

The French and West German leaders see a new political union of the 12 West European nations as a way of ensuring that a unified Germany will remain in a close relationship with the EC, rather than wandering off in search of a greater role such as might befit a reunited central European power.

Some more skeptical commentators say that the West Germans want a more tightly knit community so they can exercise their growing power, while the French desire the same framework in order to shape and dampen German influence.

The vagueness of the concept of political union has been scathingly attacked by British Prime Minister Margaret Thatcher, who insists that her fellow European leaders define precisely what they mean in the weeks ahead--before a late-June second summit here sets up a committee to work on union.

Thatcher believes that political unity should not tamper with the constitutions of the six monarchies and six presidencies that make up the EC’s 12 members.

“Let’s make it clear that political union does not mean losing separate heads of government,” she said.

Thatcher also declared that any concept of political union must not interfere with existing, separate legal systems, nor with national sovereignty.

A Thatcher aide went further, saying: “Nobody knows what it means--so how can you talk about target dates for political union?

“Do you really think the French are prepared to give up their sovereignty? Or the Germans? Of course not. It’s all rhetoric.”

Many observers believe that a United States of Europe, in the same political sense as a United States of America, will never come to pass because national leaders would be reduced to the status of American governors.

But some European leaders don’t see the concept of political unity as all-embracing. Rather, they view it as more a matter of improving existing community institutions and strengthening cooperation between Brussels, the EC headquarters, and the members.

These leaders tend to go along with proposals made by the Belgians and supported by others that see political union as granting additional powers to the European Community. That means giving the European Parliament in Strasbourg more powers to create community legislation and perhaps elect the European Commission president, increasing the range of issues on which only a majority vote of the Council of Ministers (national leaders) is necessary and establishing the principle of “subsidiarity.” This would mean that decisions should be taken when appropriate by member states rather than the community.

The more optimistic advocates of political union believe that it could be accomplished by 1993, together with the introduction of the single market in Europe.

But the optimists will have to contend with Britain’s Thatcher and some of the smaller countries that insist that Europeans need to know exactly what the grandiose concept of political unity means.

As a Thatcher aide put it: “The best way to dispel fears that political union will not cause people to lose their national identity and institutions is to make clear what we mean by it.”

Tuohy recently was on assignment in Dublin.