Global progressives are having an anxiety attack over the near-triumph Sunday of Brazil’s conservative presidential candidate Jair Bolsonaro. After years of corruption and recession, apparently millions of Brazilians think an outsider is exactly what the country needs. Maybe they know more than the world’s scolds.

Mr. Bolsonaro won a surprising 46%, just short of the 50% needed to win outright in the first round. He’s now favored over Fernando Haddad, a one-term São Paulo mayor who won 29%. The runoff is Oct. 28.

Mr....