Now personally, I feel that when someone holds a basic philosophy that if they truly believe in it they will follow through on it to the extremes of its implications. This is called being purist. There's nothing wrong with that, other than that sometimes a purist is forced to compromise and the result can often get ugly. That gets into a whole different ethical argument.
What I notice, however, is that "radical" is inherently an insult when I think its technical usage is actually relative. Whether or not you're radical depends on what you're comparing your views to. For example, the U.S. and the U.K. have some different mainstream values. If a Briton were to look at American culture and its politics in particular, that Briton might be inclined to say that Americans of both parties are radical. As we know, America has two main political parties, Republicans and Democrats, which fit into the stable two-party system that keeps itself in check, but both of those parties are closer to another end of an ideological spectrum that Britain is different on. Between them, it is my understanding that the Democratic party has more in common with British ideals than the Republican Party, so while in America the Republican party might not be seen as controversial but not particularly radical, with the exception of a few members, in Britain almost all Republicans would automatically be considered extremists.
This is a generalization, of course, based upon my understanding. Even if these statements aren't fully true, however, for the sake of the logic of this piece and my ability to articulate a point, let's just assume accuracy.
Now, if we were to turn the tables. From the viewpoint of an American Republican, British policies are extreme and radical, or at least when compared to the norm established by American political compromise.
Let me reiterate this point, but this time using something other than politics for example (although that was perhaps the most literal real-world application of these thoughts). I believe in avoiding physical contact with a partner until marriage, including kissing and the holding of hands. I've followed this logic to its natural conclusions and have even considered avoiding emotionally sensual scenarios like staying up late together. There are people who disagree with this conclusion, some more strongly than others. Fortunately, there are those who don't feel it applies to them but appreciate my view here. However, given that these views are uncommon and I take them to their natural conclusions, I am technically a radical when it comes to my relationships views. However, I no longer sense that i am a radical when I am around a group of people with shared values of how to respect the opposite sex.
From my view, I wouldn't call the views of others who don't believe in being so strict in a relationship radical. I don't necessarily call them right, though. I have my views for a reason, after all, and I believe in those reasons. Which leads me to my next point.
Just because someone is radical, doesn't mean that they're wrong. As it has been described, radical views and behaviors are merely taking basic values and following them through to their fullest implications. If the value at its core is correct, then the extreme will also probably be correct, especially if balanced out with other correct values. Keep in mind that a perfect person would be a radical, by the virtue that perfection is an extreme condition compared to the flawed nature of human beings. Superman, therefore, while not literally perfect, would count as a radical compared to other heroes in his resolve to follow up on his belief that all life is sacred. You know what? I'm pretty sure he's right.
Now, where the term "radical" gets used the most as an insult is in politics. Now let me make this clear: radicals are embraced by their own kind, who are usually the true believers in a cause and in an ideological thought process. Woodrow Wilson was a radical because he was an idealist. The reason why radicalism is often troublesome in politics is that it ruins the system of compromise that America has been founded on, and thus everyone gets hurt, even if someone believes in the right ideal. Sometimes one side will succeed and get a radical agenda past, which one might judge as a good thing if they agree with those ideals but others might judge as a bad thing if they belong to the other side of the debate. When it doesn't work, it causes political instability and opportunities for overzealousness. In American politics, people debate whether or not that's a good thing. Some people appreciate radicals of their kind in government, others don't. I'm not taking an official stance on that. I'm only pointing out the natural results.
Likewise in real life, radicalism can complicate things as you come across other people who disagree with your views. Fortunately with the kissing example, these disagreements are nothing that affect me, but there are other radical differences in views that can cause a lot of damage. What I would suggest is that these individuals should be slightly open to compromise. Perhaps that's a conversation for another day, and it depends entirely on what system of ethics you use. Willingness to compromise, for example, comes from the use of utilitarian ethics.
I still walk away from this with a few solid conclusions. Radicalism is just being a purist. It is just a relative term and is neither inherently good nor inherently bad. It's just a comparison, much like the word "change". However, like "change", it can end up either objectively for better or for worse, although we humans tend to be incomplete judges when it comes to evaluating them.