system
Given the following post, respond as if you're commenting on Reddit:
human
It's okay to downvote for disagreement. CMV.

First, if upvotes and downvotes are there to improve the quality of the comments, then why shouldn't people upvote the posts they like and downvote the posts they dislike? Preventing yourself from downvoting for disagreement just clutters up the comments with nasty people who everyone hates but nobody wants to challenge by downvoting.

Second, I also think people have walled out a little area of "agreement" and "disagreement" which they believe is somehow entirely separate from "correct" and "incorrect". If I disagree with someone who says the earth is flat, and downvote him, I'm "downvoting for incorrectness", and am justified. If I disagree with someone who says God made the earth in seven days 10,000 years ago, and downvote him, I'm "downvoting for disagreement" and am not justified. How does this make any sense? Is the second guy somehow more right because his position has supporters?

I've held this view pretty much since I started on reddit, and have seen a lot of people make a lot of angry noise about "downvoting for disagreement", but I'm wondering what's reddit's actual justification for conventional downvote reddiquette.
gpt
If the opposition clearly states their point, then you want to upvote it, because obviously you will be debunking their logic in the following reply.

Hiding bad logic doesn't allow it to be pilloried and rejected to a wide audience, which if you disagree with it, should be your objective.

It's the same reason why you don't want to censor things.  If your view is correct, then you should feel comfortable that your argument will win.  Censoring implies that you fear the disagreement.

Downvoting for incorrect facts is different, since they simply confuse the issue.  It's important to be able to discern what is an bad argument, and what is a false claim.