Like Lincoln's legs, drolly described as needing to be long enough to reach the ground, Europe's defense needs to be large enough to defend Europe.
Sounds simple enough. But wait. How large is Europe going to be? And, what about America, for half a century den mother, provider of commanders, and chief arms supplier for NATO?
NATO isn't just Europe. The US (and Canada) confirmed the transatlantic nature of the alliance stitched together to defend Western democracies against Stalin's captive empire.
But that was then, and this now. The empire isn't about to strike back. It's dismantled and partly defanged. So, outnumbered Senate opponents of enlargement argue, why plant seeds of future belligerence in Moscow - revenge for being left out of the club while lesser neighbors are invited in?
That's an argument worth careful thought, not smug dismissal. So is the related plea that a generous America did better after World War II by helping defeated enemies Germany and Japan recover and democratize - rather than walling them off.
Our position for the past two years takes account of both (1) the reasons for welcoming back the artificially walled off eastern half of Europe, and (2) generously bolstering democracy and prosperity in Russia.
We would have preferred that the organic growth of economic and cultural Europe precede the military defense of that enlargement. Let European Union grow under its strict rules of responsible economic and democratic behavior; then let NATO follow the EU map. In short: today EU, tomorrow NATO.
But, having said that, we feel that cheering on Poland, Hungary, and the Czech Republic - courageous topplers of the Iron Curtain - and then slamming the NATO door in their faces would be wrong. Historically fickle and dangerous.
So let the Senate ratify membership for these three. But thereafter, make clear that passing the EU membership tests of economic and democratic readiness is the path to entering the defense alliance.
Meanwhile, neither the US nor EU should neglect promises to Russia. Those include: (1) Helping reformers trying to democratize both the political and economic systems. (2) Making sure the Partnership for Peace deal linking Moscow's leadership to NATO planning works in a practical way. (3) Working with the Kremlin to lower barriers to trade with, and investment in, Russia's at last recovering economy. (4) Jointly working to halt leakage of nuclear, chemical, and biological weapons and know-how.
We cannot coin an acronym and assume its immortality. Who today remembers METO (the Middle East clone of NATO) or SEATO (the Asian clone)? NATO will survive as a useful entity only if it defends an organically growing body of economic and political democracies. That's the Lincoln's legs test the Senate should use.