The narrow primary defeat of veteran senator Joe Lieberman in Connecticut's Democratic primary is more than a loss for one man. It is a loss for his party and for the country. It completes the capture of the Democratic Party by its Taliban wing. They used to be "San Francisco Democrats," a phrase coined by former U.S. Ambassador to the United Nations Jeane Kirkpatrick to describe the party's 1984 convention. But they have now morphed into Taliban Democrats because they are willing to "kill" one of their own, if he does not conform to the narrow and rigid agenda of...