The Sage of Omaha, Warren Buffett, yesterday signed on to Arnold Schwarzenegger’s campaign for governor of California, apparently as an economic adviser. The Associate Press quoted Mr. Buffett, chairman of Berkshire Hathaway and a legendary value investor, as saying, “I have known Arnold for years and know he’ll be a great governor. It is critical to the rest of the nation that California’s economic crisis be solved, and I think Arnold will get that job done.”

American conservatives have been divided over Mr. Schwarzenegger’s candidacy. Enthusiasts admire the candidate’s pro-immigrant, pro-business message. Skeptics include columnist George Will, who bemoaned the vapidity of the actor-candidate’s views on the issues. We bow to no one in our respect for Mr. Buffett as both an investing genius and as a shrewd newspaper proprietor in Buffalo and at the Washington Post. Yet we have sharp political differences with him. He is an advocate of both population control and of the estate tax. Our belief is that a growing population and the ability to pass a business on to one’s family are essential to healthy economic growth. Mr. Schwarzenegger, an actor, is naturally eager for a stamp of mainstream credibility for his young campaign. But if he is to win election in California, he will need to differentiate himself from his Democratic opponents. The high-tax, slow population growth agenda of Mr. Buffett would be a step in the wrong direction.