What is extremism, and what does it mean to be an extremist, a radical?
Christian fundamentalists are generally considered extremists, even by their fellow Christians. Indeed, being a religious fundamentalist seems to be the essence of extremism, at least in most people’s minds. Religious fundamentalists distinguish themselves by claiming to follow the doctrines of their religion to the letter, and by “living” their religion (which generally means hating and discriminating against anyone they see as getting in the way of a religious society). Mainstream Christians claim that fundamentalists misrepresent their religion, and that following doctrines is not as important as things such as helping other people, getting along, or being honest about other people, all things which are not Biblical.
Agnostics likewise see atheists as extremists. They consider that no one should claim anything as true or false (an admonition which, of course, they do not follow in any other area of life). They claim that all points of view should be respected, and that anyone who claims anything to be the absolute truth is not being reasonable (all the while not realizing that the points of view themselves would not exist without at least some people who uphold them as the absolute truth). As you can guess by my asides, I’m not a fan of agnosticism: but my point here is that agnostics accuse atheists of being decisive.
Pretty much the same scenario repeats with skepticism. Skeptics are, more or less, the agnostics of the paranormal world, and decry people who deny paranormal claims out of hand (such as myself) as “cynics” and “close-minded.” Skeptics will obsess over the smallest details of a crackpot claim in order to determine how to test it. They believe that the crackpots are irrational but they refuse to take this to its logical conclusion, because the conclusion (that we should give no credence to things people make up) is too harsh for them and not “nice enough” for public consumption. They also shy away from debunking most political or religious claims (or indeed, prop them up) because they don’t want to appear too weird to the mainstream.
Anarchists are, obviously, also considered as extremists, because they claim that there is no justification of the State and that we’d be better off without one. A common argument against this position is, “there are some good governments and some bad ones, you need to reform the system instead of complaining about it.” Even if it is uncontroversial that some governments are better than others, the Anarchist remains unmoved by such an objection because he fights against the State as illegitimate authority and mechanism of oppression, not against fascism or communism or democracy alone. This is an extremist position.
You may be noticing a constant between all these examples. Whether they distinguish themselves on issues of morality (religious fundamentalists, Anarchists) or on issues of reasoning (atheists, “cynics”), extremists share one property: they uphold (some) principles above the demands of pragmatism.
When I say pragmatism, I mean that a person believes and acts in such a way that they escape the natural conclusions that would arise from their beliefs. The liberal Christian professes to believe in Jesus and the Bible, but ardently refuses to acknowledge any consequence emerging from anything the Bible says. The agnostic and the skeptic refuse to take anything on faith or to blindly accept claims, but denies the natural conclusion that we should reject religious or paranormal claims. The minarchist believes that governments are inefficient and corrupt by nature, but refuses to accept the natural conclusion of Anarchy.
There is some merit to the belief in pragmatism. Obviously it is dangerous to follow evil principles, and in those cases one would do well to be pragmatic about what to uphold. People who strongly uphold evil principles are the most dangerous. This is often used as the proof that principles are dangerous. But the more obvious conclusion is that evilness is dangerous, not principles. Principles in and of themselves are tools of reasoning, and we must use them constantly in our daily lives, whether we like it or not.
Of course, people are generally not very careful about the principles they decide to follow. Especially in the cases of religion and politics, they often take such decisions based on emotional struggles or self-doubt. This is why reasoning and exposing one’s own premises is so important: because there’s nothing more poisonous than a hidden immoral premise.