So you're arguing, then, that there's no point in trying to be "less wrong"?

Not at all. If you have many arguments, it is useful to reduce the number of them that are invalid and increase the number that are valid.

An argument itself, though, can be only valid or invalid. If some section of it is incompatible with the rules of logic, it's in violation of those rules and cannot be valid.

Either you're absolutely correct or you're "deeply misguided and silly" and can't "engage in clear thinking"?

Again, not at all. A valid argument isn't necessarily true, for one thing. For another, merely not violating the rules doesn't imply correctness - if you never construct an argument it can't violate logic, but you'll never reach a true conclusion that way. People often refuse to investigate theses when they don't want to have to acknowledge an unpleasant truth that they suspect lurks at the end of a chain of reasoning. That is an error of integrity, not (directly) one of logic.

Your attitude doesn't seem conducive to creating harmony amongst mostly like-minded people.

Setting harmony as an goal is destructive and misleading. Seek the truth, and to ensure that everyone applies the appropriate standards of evaluation, and harmony will arise as a natural consequence. Try to create harmony directly and you become trapped in falsity and error.

There can be no 'harmony' between theists and anti-theists, for example. The two positions are incompatible. Logic and the available evidence support one and not the other. This community should not seek to create harmony of that sort; by insisting on rigorous standards of reason, the community requires that theists must either abandon their position or leave their association with the group.

(Or, of course, keep their beliefs secret and imply by silence that they're not theists. It is difficult to identify such a strategy. LW does not have inquisitors...)