One of the most quoted pieces of folk wisdom is that "voters don't like divided parties". The implication is that a political party which can't keep its own house in order is unlikely to be trusted to run the country. This month epic disunity has been on display in both the government and the opposition. Bitter divisions have become almost routine among Conservative MPs, as they have dethroned and installed five leaders and prime ministers in just eight years. Division in Tory ranks has undoubtedly been an electoral asset for Labour, helping to explain its massive lead in opinion polls....