Anti-intellectualism
The phrase anti-intellectual is problematic.
At first glance, some (see other answers for this question) appear to conclude that the phrase means ignorant. But this not my understanding. Nor, is it the authors of the Wikipedia page on the subject:
https://en.wikipedia.org/wiki/Anti-intellectualism
Yet, for me, anti-intellectualism can only be anti-reason. I don’t think anti-intellectualism is necessarily anti- knowledge, education, philosophy, etc.. For example, the Marxists, postmodernists, and Critical-Theorists are themselves anti-intellectual. Yet, these groups would not consider their beliefs ignorant. In fact, they believe their views to be informed TRUTHS. And that’s the problem. The anti-intellectualists simply don’t want competitors to their views empowered. Yet, reason isn’t a competing view, it instead makes possible any number of competing views. For the anti-intellectuals, reason cannot be discredited as an idea, it must be entirely eliminated. Thus free thought and speech are an anathema to the anti-intellectual. In the extreme, both the body and sole of the competitor is eliminated, as has happened all too frequently.
Tactically, in the absence of rationality, beliefs are acquired and held somewhat dearly by irrational people. The emotional defenses for beliefs held by a person like this are strong. These individuals can and will resort to violence in defense of their beliefs. This is a serious and dangerous problem when it happens with groups, especially as the groups grow in size.
Ideas held irrationally become semi-permanent fixtures of the person’s psychic-self. Acceptance of irrational beliefs occur often in emotion (related to the self’s safety or well being). These irrationally acquired ideas become as critical to the psychic self as arms and legs are to its physical self. In fact, to the Ego and its emotional defenses, arms and thoughts are the same. This is because the self believes that these ideas are essential to the psychic self’s survival. And without prior rationality on the subject, the psychic self lacks the foundational reasoning elements to correct them.
Thus, ideas emotionally acquired through fear, anger or other emotion (related to the safety of the self) in the holder, will not be surrendered by subsequent reason alone. The source of the emotional response must be neutralized first. This is not trivially accomplished in the presence of accompanying emotional reactions.
Anti-intellectualism is therefore a defensive strategy for emotionally (not rationally) held beliefs of an individual or group. The fight or flight emotional responses apply—even for beliefs.
It’s dangerous, and it can happen anywhere.
Final note. Irrational people can be smart. Marx was one. But his views were irrational, and they appeal to the irrational. See my web-site on the subject.