Apparently, the difference between Leftist intolerance and conservative intolerance is greater than previously thought:
But more recent psychological research, some of it presented in January at the annual meeting of the Society of Personality and Social Psychology (SPSP), shows that itâ€™s not so simple. These findings confirm that conservatives, liberals, the religious and the nonreligious are each prejudiced against those with opposing views. But surprisingly, each group is about equally prejudiced. While liberals might like to think of themselves as more open-minded, they are no more tolerant of people unlike them than their conservative counterparts are.
If prejudice is equal between the groups, then Leftist prejudice is greater than conservative prejudice. The reason for this is found in ideology: a philosophy of what “should” be, such as Leftism a.k.a. egalitarianism, demands universal compliance in order to be seen as legitimate. Conservatism, on the other hand, demands that people not violate things seen as sacred by the community.
We can observe this through history. Right-wing groups tend to crush the opposition, where Left-wing groups crush those who do not affirmatively become part of the ideological movement. It was possible to be neutral in Nazi Germany, but those who did not signal that they were good Communists in the Soviet Union were immediately at risk.
For the Leftist, non-compliance is dissent. For the Rightist, there is compliance, opposition and neutrality.