ONCE derided as the scheming of crackpots, the campaign for boycotts, divestment and sanctions against Israel, widely known as BDS, is turning mainstream. That, at any rate, is the fear of a growing number of Israelis. Some European pension funds have withdrawn investments; some large corporations have cancelled contracts; and the American secretary of state, John Kerry, rarely misses a chance to warn Israel that efforts to “delegitimise” and boycott it will increase if its government spurns his efforts to conclude a two-state settlement of its conflict with the Palestinians.