I'm a proud, apoplectic, left wing, radical!
There are a lot of ostensible Leftists here on Kos. Enough to disprove the idea that the Left is some sort of monolith. There's a wide spread and variety of opinion. So any criticism of "the Left" is by definition going to be partial rather than general. There's no "party line", contrary to what both some Leftist and their opponents would prefer to think.
What you have is a number of trends in thought and opinion, some of which are in conflict with each other. Not all leftists think that Noam Chomsky hung the moon. Not all Leftists treat Marx as gospel. Not all Leftists view Liberalism as a greater threat than the RW. Likewise, there are Leftists who do. The Left, such as it is, is a mixed and unruly bag.
Such a hodgepodge requires the use of critical analytical skills to make one's way through the thickets of competing views and opinions.
Not everyone is comfortable with this. Some seem to think that the Left should be exempt from critical self examination. This is a mindset that refuses to recognize error or account for its failures. A mindset that explains every loss in terms of forces beyond its control. That implicitly denies its ability to influence or shape events. That, consequently, produces an exaggerated siege mentality that treats any suggestion of critical self examination as an attack. Such attitudes are getting a lot of play in the current NSA debates.
For some of us this has a very familiar and dismal aspect. Self ghettoization and the resultant insularity and sectarian blindness have been a perennial plague on the Left. It has contributed substantially to the marginalization and consequent political irrelevance of the Left in the US.
Apparently, some political fundamentals need to be re-emphasized.
The first among these is that a refusal to consider criticism, whether constructive or hostile, is a sign of political and ideological bankruptcy. It amounts to a refusal to learn from mistakes. Indeed, a refusal to admit the possibility of error. This is true regardless of the bias of the critic. If you want to learn where the weaknesses of your own arguments and analysis are located, the best place to look is in the critiques of your political enemies. Particularly so when they've been cleaning your clock for several decades.
This would seem obvious but you would never know it from the way that some react. For far too many the substance of a criticism takes a back seat to political bias. Far too many seem to believe that the presumed or actual political bias of a critic some how invalidates the factual substance of a criticism. For some this canard has taken on the status of a theoretical absolute, despite its being the textbook definition of the ad hominem fallacy. Equally destructive is the correlative belief that any dissent from the supposedly "orthodox" Left position identifies the critic as a political enemy.
Again, this is nothing new. Nor is this sort of ersatz religiousity unique to the Left. However, it's no concern of mine if the RW and other reactionary movements engage in this kind of ultimately self defeating behavior. In fact I would encourage them to do so. Nothing would suit me better than to see them sideline themselves in the same way that the Left has repeatedly done over the last 40 years.
What does concern me is the need for a healthy, militant and effective Left in the US. If either the US as a democracy or the planet as a whole are to survive, this is the immediate and overriding necessity. The stakes do not allow for indulging in this sort of ritualism. A quasi theological intolerance for differences of opinion isn't something we can afford. A movement more interested in creating enemies rather than creating allies is an irrelevance in the making.