I generally tend to avoid the "language war" threads for 3 reasons: 1. No one is really right or wrong. 2. Not much gets accomplished. and 3. It really doesn't make that much difference anyway.
Debates about favorite colors, on the other hand, should be strongly encouraged. Blue is definitely the best one.
Your point that not much is accomplished by such discussions is definitely what usually happens. But it isn't what must happen. There are rational ways of discussing these subjects which can lead to knowledge creation and agreement.
The reason I'm posting is basically that I think people are a little too quick to give up, and if they tried to discuss seriously a bit more, they might find it sometimes works. Especially if they are careful to ignore the bad replies they get and only reply to the other people who are also taking the discussion seriously.
Well, yes and no. There's only a truth to the matter if you can get people to agree on a premise. Two libertarians who adopt the same premises can have a meaningful debate with each other. They'll agree that there can only be one consistent position -- so if they disagree on what it is then one of them must be mistaken -- and set about trying to figure out which of them holds the fallacy. But if you pit a libertarian with the premise of self-ownership against a communist with the premise of "property is theft", nobody is going to accomplish anything because neither will view the other's argument as relevant.
This is the myth of the framework. See Popper's book by that name:
http://www.amazon.com/Myth-Framework-Defence-Science-Rationa...
Besides the issue of whether productive debate is possible across frameworks, there is also your (possibly accidental) assertion that what premises people believe affects what statements about reality are true (beyond statements about who believes what). That's solipsism.
None of the statements in question have to do with reality, only with abstract ideas. Libertarians believe that property ownership is a right; communists believe that it is an offense. Neither of these assertions is empirically testable.
If the debate is about what policies will make us wealthier rather than what policies are ethical, then that's a different matter. But in that case, both sides are sharing the common framework of utilitarianism.
Which policies are ethical, with "ethics" rightly construed, is also a matter of fact. Morality is about how to live, and it's not a religious concept. The notion that morality is (and must be) religious is unfortunately a bad, religious idea, that (oddly) most atheists still believe.
Just to get started, we can consider which lifestyles do and do not accomplish their own internal goals. Lifestyles that do not are bad ways to live -- they are "immoral". We don't have to use moral terminology; that isn't important. But whatever you call it, there are objective facts about how we should or shouldn't live.
And there's better than that. You can take a very wide variety of goals, and examine how to achieve them. And you can find common points -- certain ways of life are good for achieving many goals, while others are not. These common points, which make people powerful and able to accomplish things in general, are an important, useful, and objective find the field of morality.