Should a political party craving power be true to its hardest-working loyalists, who are usually on the ideological frontier? Or should it cater to the throng of uncommitted voters in the center who grant or withhold office?
Conservative Members of Parliament decided that question in Britain, this week, on the side of moderation, stability and the broad center.
They must expect to lose the next election, by mid-1997, anyway. The struggle for the soul of the party was really about how badly to lose, and how long to remain in the wilderness afterward.
The Labor Party sailed out of office to oblivion in 1979 while veering sharply to the left. Subsequently, led from the left and goaded from the fringe, it worried mainly about being true to socialism.
Meanwhile a triumphal Prime Minister Margaret Thatcher was drastically reforming British life on Conservative lines.
This led to the defection from Labor of some its best minds to form a fourth British party, the Social Democrats -- which only made Labor weaker and lefter.
The self-destruction of Labor was the secret of Mrs. Thatcher's long and effective tenure while supported only by a plurality of the fragmented British electorate.
But eventually, Labor righted itself, under a series of centrist leaders. The Social Democratic meteor flared out. That party merged into the Liberal Party, lengthening its name to Liberal Democrats.
Britain is once again basically a two-party country, even with the third-party Liberal Democrats (claiming to be radical) in the center, and with Celtic fringe parties in Scotland, Wales and Northern Ireland.
The conventional wisdom that the center wins elections took a beating during the Thatcher years. She charged to Conservative leadership on a promise to be truer to principle than Prime Minister Edward Heath had been. She kept it.
That coincided with the Age of Reagan in the United States. The belief arose on both sides of the Atlantic that society had become permanently more conservative, and that the pendulum had stopped swinging.
But Labor's new leader, youthful Tony Blair, completed the rout of its left. If the Tories abandon the center, Labor is all over it. Mr. Blair has none of Labor's traditional roots. He more closely resembles people who used to be found in the Liberal Party or left wing of the Conservatives.
Irritation with Mrs. Thatcher, scandals of a party in power too long and the likelihood of losing led to the coup from the party's left which toppled her in 1990. The successor, however, was her own choice, the bland John Major.
Mr. Major surprised everyone by leading the party to victory in 1992 but since then has presided over a continued slide downward. The Tories have been in power too long. They are on the way out.
Conservative dismay with Mr. Major's leadership, as a threat to each MP's seat, is general. The hard right tried to capture it for the cause of ideological purity and fear of erosion of sovereignty within the European Union. (Never mind that the Conservative Heath government took Britain in, 23 years ago.)
But MPs who may be worried at Mr. Major's performance were not swallowing the policies or personality of his challenger, John Redwood. If it is true that the center wins elections, that would have been lunacy similar to Labor's leftward binge in the early 1980s.
Hence Mr. Major's victory, the triumph of the Conservative center.
But Mr. Blair and Labor are poised to win the next election anyway. They will impose a cabinet untainted either by old Socialist rhetoric or by experience in office.
A Conservative Party appealing to the center would be ready to recoup as soon as the Blair government faltered. A Conservative Party gone off to the loony right would give the next Labor government longer to get its act together, as Labor on the loony left did for Mrs. Thatcher.
The U.S. Democrats faced such a choice in 1992. Bill Clinton won the nomination as a centrist. Then he took power as a champion of liberalism. Now he has rediscovered his centrist purpose, to the dismay of liberals. In a word, he is beatable.
Republicans are battling with similar demons. Whether to appeal to moderates who vote, or to extremists who provide the party its passion, is what the primaries and national convention will decide.
It is not clear that Republicans will opt for the priority of electability, as British Conservative MPs did this week. There is hope for Clinton yet.
Daniel Berger writes editorials for The Baltimore Sun.