Israelis went to the polls Tuesday to elect a new parliament and prime minister. By yesterday, despite high turnout and 99% of the vote counted, nearly everything was clear except the actual winner.

Chalk that up to an electoral system based on proportional representation, which encourages smaller or one-issue parties to compete rather than merge with larger parties. The result, this time, was that by early Wednesday morning two candidates could credibly claim to have won.

Tzipi...