On Saturday, Musk announced he was forming a new political party called the "America Party," and on Monday shares in Tesla tumbled 6.8 percent.

Before we assess the eternally unrealized dream of a potent third party in American politics, let’s consider the specific, recently emergent dream of one specific man: Elon Musk.

Instead of the quadrennial dream of No Labels, in which high-minded donors put up the money for an imaginary white knight who never materializes, we may get the “America Party,” in which the world’s ...