Idiocy and Cognitive Dissonance

The scientific method consists of three parts: hypothesis, a prediction based on similar experiments, the experiment based on the hypothesis, and the analysis of the experiment summarized in a conclusion.  This is a dispassionate process, logical to the extreme by necessity, and the emotions or prejudices of the scientist can not change the outcome of the experiment less it be voided on that basis.
If one would allow the same for a social experiment, I can not understand the defense of political vitriol in light of the Gifford’s massacre.  It was hypothesised that it would lead to violence, the “experiment” yielded violence and, yet, the some of analysis of it would try to persuade you that the vitriol that formed the hypothesis had no bearing on the outcome.  This is illogical, irrational.  There must be some reason why the defence has formed.
In reading some of these defences, the word “idiotic” kept coming to mind.  So much so that my mind deconstructed the word to its root, id, one of Freud’s three psychic aparatti.  The id is pleasure driven, instinctual, though Freud considered that “the id, the whole person…originally includes all the instinctual impulses…the destructive instinct as well”.  As this thought settled on me I began to consider the possibility of irrationality, immaturity, unawareness on the part of the defenders.  How could they possibly still not see this before them in all its bloody horror?
It was then the thought of cognitive dissonance occurred to me.  If these individuals, the defenders, were so id controlled, how could any rational argument dissuade them, how could any incident cause reflection,  how would any occurrence not be seen as anecdotal?
In other words, I’m asking the defenders of vitriol, what is the exact number of times this has to happen to make you believe?  Is there any number that would satisfy you?  If there is not, you are irrational, scientifically proven.
I am convinced on the basis of the experiment already performed.
I make these statements with no knowledge of what the murderer will say.  I will not speak his name.  He seems to me the embodiment of the id controlled, with no conscience or capacity for empathy.  In colloquial terms, an idiot.  Who would defend him?

Addendum: after posting this, I realized that the summary was indistinct.  I’m not taking a political stand here, I’m saying the refusal to link the violent rethoric with these murders is a sign of mental illness.