TAIPEI—No dogma is more important to Beijing than “One China,” the concept that Taiwan is a part of a single Chinese nation—just temporarily estranged.

America and much of the rest of the world acquiesce to that position, denying the reality that Taiwan has set its course as an independent state. Last weekend’s vote, in which the Taiwanese electorate overwhelming endorsed a party that rejects Beijing’s “One China” formula, confirmed the direction in the most emphatic way to date. That not only puts China in a bind, but the...