Lack of self-criticism is not a big problem on the "left." It is so not a big problem that the rhetoric of a consequential faction of the left during last year's election season was virtually indistinguishable from that of the Trump campaign. It is so not a big problem on the left that the left could not even galvanize its voters to defeat the odious Donald Trump. The liberal commentators I read regularly criticize various tendencies on the left. Indeed it is a mantra on the left that the left seems incapable of moving in lockstep like the GOP because of all the internecine squabbling.

<<"Left" tends to argue on the basis of inherited conclusion. It has lost the capacity to reason why, or convincingly.>>

I've got to wonder, what sources of liberal thought do you read that are lacking in reasoned argument?