The temptation to criticise one's political allies exists because criticism can help individuals derive personal advantage, either within the group or by forming temporary alliances outside the group. Refraining from criticising your allies is a strategy of deferring or sacrificing individual benefits for the good of the group. But Republicans are supposed to be individualists! Democrats are supposed to believe in collective action for the good of the group. And yet Democrats are perfectly awful at collective action. Democrats are constantly undercutting their presidents; liberals have been lukewarm and quick to turn on Carter, Clinton and Obama, and no Republican president has ever faced the kind of fury from his base that the left directed at LBJ.