The note that Joe Stack left behind when he set off to fulfill his murderous ambitions is emblematic of a break down in discourse.
In Dawkins' The Selfish Gene, he talks about memes which serve the function of preempting the analysis of other memes. Dawkins being Dawkins, his primary example of a defensive meme is the concept of religious faith, and the concept that 'G-D works in mysterious ways'. At the end of his manifesto, Mr. Stack employs a similar defensive meme
I saw it written once that the definition of insanity is repeating the same process over and over and expecting the outcome to suddenly be different.
...at the end of his manifesto to justify the insane course of action of flying a plane into a building to murder employees of a bureaucracy he didn't like.
I think its important to understand the function this meme fulfills. First, it appeals to people with a familiarity with science, by defining insanity as the opposite of science - wherein a disconfirming result should force the abandonment of a hypothesis. Second, it caricature's one's opponent through oversimplification - almost no-one to whom it is applied is literally doing the same thing and expecting a different result, they are instead doing similar things. They may in fact be applying a meme of stubbornness, such as 'when first you don't succeed, try, try again'.
Third, it defines one's opponent as insane, with all of the concomitant characteristics of that claim. Most believe its irrational to debate crazy people - yet are the failure to learn from one's mistakes, or stubbornness indicative of insanity? If they are, then how many of us were quite insane during our teenage years? Since most won't debate those they believe are insane, insane must mean more than 'stupid + stubborn'. Barring that, one is simply pretending that the exceedingly difficult task of debating someone who is stupid + stubborn is in fact the impossible task of debating someone who has no consistent and rational worldview.
This sort of oversimplification-through-cliches is repeated throughout Mr. Stack's manifesto. He explains that he hopes this document will be therapeutic, though "my gross inability to gracefully articulate my thoughts in light of the storm raging in my head" leads him to question whether or not it will be effective:
Exactly what is therapeutic about that I’m not sure, but desperate times call for desperate measures.
Desperate times call for desperate measures in this case is being employed backwards. That is, by choosing a 'desperate measure', Mr. Stack is hoping to demonstrate that he was in 'desperate times' - but while a may imply b, its nonsense to reverse it and declare that b implies a.
Of course, as Mr. Stack declares, those who disagrees with him have been "brainwashed".
We're brainwashed if we believe that our government advocates "justice for all", or if we believe that "there is freedom in this place".
Whether those claims are true or false is beside the point - the problem with making this claim is that it invalidates the possibility that people could disagree with you on it. Either you agree with Mr. Stack, or you are brainwashed.
In Hannah Arendt's Eichmann in Jerusalem, she talks about the repeated use of cliches in Eichmann's explanations for his actions. He was concious of the cliche nature of his explanations, saying that he spoke in 'winged words', an expression which Arendt explains is a German cliche for famous quotes, though she notes in the erudite tone that often gets her accused of arrogance that it is ironic in Eichmann's case, since he isn't applying it to scholarly quotes, but instead to folk wisdom and political slogans.
I'm not sure the problem with Eichmann's 'winged words' is that they weren't winged enough. I think that the problem with people who use ideology to justify harming others is that they're using ideology to justify harming others.
Baruch de Spinoza, a refugee of the murderous certainty of the Spanish inquisitors said that "Tolerance is the antithesis of the Inquisition", and defined tolerance as "the freedom to err". I hope that we all can try to extend tolerance to those who disagree with us; the freedom to be stupid, not matter how stubbornly our opponents repeat their errors.