A NEW German-French proposal for a joint military brigade of up to 50,000 soldiers makes sense for a number of reasons, political and psychological. The plan doesn't appear to have any real negatives, unless the Germans decide to use NATO forces for the new brigade. That would contradict Bonn's earlier indications.In Europe, NATO still provides a stable security structure for both the continent and its biggest country, Germany. NATO is diminishing somewhat in force strength and influence as the immediate Soviet threat lessens and as Europe works at union. But for now it's a pillar that all Europeans can count on, as Czech president Vaclav Havel told George Bush last week. The Persian Gulf war and the current war in Yugoslavia show that on security questions European unity has not yet jelled. A Franco-German brigade is the first real attempt at military and security coordination outside of NATO. If it works, it would allow the Germans a way to participate in "out of area" conflicts - something they could not bring themselves to do, for historical reasons, during the Gulf conflict. The brigade would also bring the French into the security picture in Europe, without pushing them to send forces to NATO, something they would abhor. The larger rationale for the brigade is political. It is doubtful that the Franco-German troops will be used for actual fighting anytime soon. Certainly they won't go to the Yugoslav inferno. However, if the effort is successful, the two dominant nations on the continent will show each other, and the world, that they can work together on sensitive issues. The impulse for a European force works hand in hand with the desire for economic and political union in Europe. It adds to a picture of unity as the EC leaders meet in the Netherlands in early December to ratify a modest political union. It's still unclear whether the Franco-German brigade is an effort at an end run around Britain, which does not support the idea of a Western European Union (WEU) force run by the European Community in Brussels. The British want autonomy on security matters, which makes sense. It should be pointed out, however, that NATO has always encouraged a separate European security identity.