Intelligent debate is a rarity; few people are able to engage in intelligent exchange of opinion, or even tolerate the airing of another's opinion, if it is contrary to their own.
Freedom of Speech means supporting the right of others to state their opinions, especially those you disagree with.
Shouting down others that you disagree with, and trying to take away their right or ability to state their position are the tactics of Fascist states.
A great example is the atmosphere surrounding any challenges to the "Global Warming" mantra. . . . Ten years from now, it will be revealed as this decades' equivalent of the Red Menace, or the Population Explosion, or the Y2K meltdown, or the big "scare" of every other decade . . . . but for now, if you are a scientist with a legitimate opinion that goes against the "Warmists", you are effectively blacklisted.
Pretty disgusting state of affairs.