What's the preferred way to deal with...

[Komatik]

...a person who butts into threads and is not willing to take part in an actual discussion, thus constantly degrading the value of otherwise interesting threads.
Yet, he never attacks anyone personally, simply acting as a neverending font of demonstrably wrong claims which he never accepts as wrong ones?

Is the Ignore button the only acceptable salvation?

[MikelaC1]

Report his posts and let the moderators deal with him.

[Savannah]

Report. If any single post isn't quite enough to break the rules, you can certainly explain in your report the consistent pattern you're seeing, and maybe include links to other posts to support your position. (Actually, even if the post does break the rules, you should still explain the pattern so the mods know it's not just a one-time thing.)

[Roland St. Jude]

Sheriff: If it seems to you that the person is trolling, then report the offending post and link to or clearly identify the other posts involved. We're certainly willing and able to judge a whole course of conduct.

But what you describe may well just be someone who has a different perspective from, or starts at a different premise than, you (or everyone else here).

As with anyone who disagrees with you, you can ignore them, Ignore them, or try to inform them. If someone seems unwilling to listen to reason, then don't waste your time engaging them. There's nothing that prevents posters from simply stating their disagreement with Mr. Wrong and then continuing on with the discussion. Sometimes people are wrong on the internet.