Nothing wrong with having an earned downvote if you in fact think somber thoughts about using it.
I could perhaps support a change to earning each downvote, further encouraging contemplation ("do I really want to burn a downvote on _this_?").
I reserve downvoting for useless comments (e.g., "me 2") or ad-hominem or other offensive attacks.
The problem is it seems reasonable enough...it's certainly more reasonable than downvoting someone because you don't like them...
However, it's is absolutely not an appropriate use of downvoting and is harmful to discussion quality.
To begin with, someone being "objectively wrong" is MUCH more rare than you probably think. Purely in terms of mathematical probability, I can pretty much guarantee there was a time you thought someone was wrong on the Internet when in fact you were the one who was wrong. There are many times when LOTS of people thought Joe Shmoe was wrong, but Joe Shmoe was in fact correct and everyone else is wrong.
Many times even though what the person is SAYING is wrong, but there is a mis-communication somewhere. You may be reading it the wrong way, or they may not be expressing themselves clearly.
This brings up the main problem with what you are talking about: it shuts down the conversation....and that is incredibly bad for a community that is supposed to be build on discussion.
Let's say someone's wrong. You downvote them. You've accomplished effectively nothing. Some people might not see this wrong information....but that's neither here nor there.
A MUCH better solution is to reply and explain to them how they are wrong. That way the discussion continues, and they are educated (whether or not they decided to take advantage of it).
More importantly, if one person thought this wrong thing....there are probably many others who also thought it but didn't post it.
If you reply with a correction, those people are also enlightened. This ties in with my earlier point...you may have prevented some people from seeing the wrong information, but there's no reason to believe that it balances with the people you could have educated by responding.
Keep in mind, none of this is even taking into account abuse of such a feature, which would occur.
All around it is by far better for the community to correct wrong information than to censor it....not to mention the latter is impossible to do effectively.
I don't know. Objective wrongness ranks low on my list of reasons to downvote, which is usually because a post is off-topic or intended only to insult the parent. Consequently, I rarely use the downvote option.
If I think someone is wrong, I usually respond with an explanation, or wait for someone else to do the same.
http://news.ycombinator.com/item?id=117171
writing, "I think it's ok to use the up and down arrows to express agreement. Obviously the uparrows aren't only for applauding politeness, so it seems reasonable that the downarrows aren't only for booing rudeness.
"It only becomes abuse when people resort to karma bombing: downvoting a lot of comments by one user without reading them in order to subtract maximum karma. Fortunately we now have several levels of software to protect against that."
There have, of course, been several years of a greatly expanded HN membership since then, but downvotes still serve a purpose, and users with sufficient karma are trusted to use them wisely. See
http://news.ycombinator.com/item?id=2403696
for announcement of a persistent problem only this year,
http://news.ycombinator.com/item?id=2434333
for an announcement of an experiment (which looks to have been successful)
http://news.ycombinator.com/item?id=2595605
http://news.ycombinator.com/item?id=2595783
to fight the problem of comments "that are (a) mean and/or (b) dumb that (c) get massively upvoted." Downvotes are a way to fight such a problem too.