Shame derails critical thinking because truth is not the shame ego’s main objective. The shame ego’s main objective is looking good in the eyes of others. Put another way, the main objective of the shame ego is to avoid humiliation. Put another way still, the shame ego’s worst fear is being humiliated.
If the shame ego were primarily interested in the truth and thought critically it could hear both sides of a debate and determine the winner objectively based on the merits of each argument alone. But with political debates in particular I find that most people do not evaluate the arguments primarily on their merits but rather based upon pre-existing loyalties to political camps and not wanting to appear foolish in the eyes of the opposing camp. I do this myself. When I do this I must realize that I am allowing my shame ego to take control of my thought process and am therefore not thinking critically.
In this context, loyalty can be a tricky subject. Most people think loyalty is an admirable quality. I would say, generally speaking this is correct. However, shame egos are more apt to invest their loyalty for the wrong reasons in the wrong causes. For example, a shame ego might be loyal to a cause because it does not want to appear to be following the wrong or loosing side. It is not so much that the shame ego ignores its critical thinking, but rather the shame ego prioritizes not appearing foolish or wrong above what cause actually deserves or has earned its loyalty. This is why (I believe) arguments involving religion and politics devolve into shouting matches and ad hominem attacks. These type of arguments are about personal beliefs and therefore in some ways define the people making them. If their beliefs are wrong then they as people are wrong. Shame egos cannot abide by this.
Critical thinking requires dismissing shame in order to be objective but a shame ego will not allow this. As such, a person with a shame ego never properly learns to think critically and therefore experiences a warped sense of reality and truth. At its heart, the shame ego is afraid of truth because the shame ego ultimately believes itself to be wrong. As such the truth (it believes) is humiliating and must be avoided, hidden or dismissed. In fact, a shame ego will sometimes deny truth even to itself and will react with anger or aggression against the people who insist on the truth.
Rather than feel the discomfort a shame ego experiences when confronted with the truth it will avoid the truth and therefore is incapable of thinking critically. In order for a person to think critically he must free himself from his shame ego. He must embrace the truth and allow himself to experience humiliation in a supportive, non-judgmental environment. If he is judged then the humiliation becomes too harsh and he will retreat back to the protection of the shame ego. But if he is not judged and can take in the compassion in the face of the feeling of humiliation, then he can start to have compassion for himself. This is the first step in the arduous road to liberation.