user254: I don't upvote when I don't understand the answer
Often other people post answers, to questions which I don't know the answer to.
If I read their answer, and suspect that it's a good answer, even so I don't upvote their answer because I'm not certain that it's correct, because 
I worry is that the sequence of events might be:

Someone posts a difficult question
Someone writes a plausible but incorrect answer
I read the answer and (being ignorant) think "it looks good to me", and (being careless) I up-vote it
The next person who reads it sees, not only a wrong answer, but an up-voted wrong answer: my up-vote will have made the problem (bad answer) worse, and would be wrong speech.

Therefore there are answers which I don't up-vote, because I'm not sure of them: they're not bad or boring answers, they are answers to difficult questions.
I don't upvote if I think it's not a good answer
Theoretically there might be another, completely different reason for not up-voting an answer: which is that the answer isn't very helpful.
Can we tell the difference between different kinds of upvote? What does it mean if an answer has no votes?
Here's a proposal: if you read an answer that's not helpful, if you don't want to up-vote it because you think it could be better, if you see a way to improve it, how about add a comment to criticize it?
At the moment when I see an answer with no up-votes and no comments, I can't tell the difference between:

This might be a good answer but there's no-one competent enough to judge (up-vote) it
There are people competent to judge and they have decided that it was not worth up-voting


If you answer this question feel free to include personal answers: e.g. "yes, criticize my answers" or "no, don't criticize my answers" and/or "I do/don't like to criticize other people's answers".
I admit that criticism can seem dis-harmonious, and that SE is not intended for discussion/dialog.
OTOH some people post answers in public, not only to help others but in the hope that if their answer can be improved, someone will point that out.
See also Vote Early, Vote Often

user43: Re: voting, if you don't really understand an answer, do not vote.
Re: criticism, I only downvote and criticize an answer when I see the topic clearly enough that I can be certain that my understanding is complete and the answer is mistaken.
If you have only a vague understanding of the topic, and can't really follow the reasoning of the answer, but the answer seems to mismatch some postulates/axioms you have heard about, ask a new question!

user254: 
If an answer is bad (useless or worse), then you should down-vote it and leave a comment. The comment is:

To tell the person who posted it why it's down-voted, so that they can (if they wish) improve or delete their answer
To warn other readers that there may be something wrong, and specify what you think is wrong, so that they can judge for themselves.

If you totally don't understand an answer then you can ask a separate question. If there's an expert answer which contains several complicated expressions, which were intended as an answer to the original question, it doesn't make sense to question those too much:

Because comments aren't a suitable place for expert answers: asking a separate question allows room for one or more corresponding answers
Because changing the subject might detract from the original question and original answer

If you see an answer you don't really like (which is "meh"), make sure that a better answer exists even if you have to write that answer yourself. You can write a whole answer; or just write a partial answer, for example instead of asking someone to add to their answer, you could write, 

In addition to the other answers, ...

or

Further to so-and-so's answer, ...

Comments to an answer are for minor conversation about that answer, between you and its author. You nearly understand something but not quite, or you're not sure? You think you understand, but maybe the answer can be worded in an alternative way? Then comment. The author can:

Ignore the comment
Reply to the comment
Edit their answer
Flag the comment as unhelpful


About me:

I like to comment occasionally, e.g. to verify whether I understand an answer
I hope I don't mind receiving comments on my answers
Feel free to delete any comments of mine if they are not or if they stop being useful


254: <h2>I don't upvote when I don't understand the answer</h2>

<p>Often other people post answers, to questions which I don't know the answer to.</p>

<p>If I read their answer, and suspect that it's a good answer, even so I don't upvote their answer because I'm not certain that it's correct, because 
I worry is that the sequence of events might be:</p>

<ol>
<li>Someone posts a difficult question</li>
<li>Someone writes a plausible but incorrect answer</li>
<li>I read the answer and (being ignorant) think "it looks good to me", and (being careless) I up-vote it</li>
<li>The next person who reads it sees, not only a wrong answer, but an up-voted wrong answer: my up-vote will have made the problem (bad answer) worse, and would be wrong speech.</li>
</ol>

<p>Therefore there are answers which I don't up-vote, because I'm not sure of them: they're not bad or boring answers, they are answers to difficult questions.</p>

<h2>I don't upvote if I think it's not a good answer</h2>

<p>Theoretically there might be another, completely different reason for not up-voting an answer: which is that the answer isn't very helpful.</p>

<h2>Can we tell the difference between different kinds of upvote? What does it mean if an answer has no votes?</h2>

<p>Here's a proposal: if you read an answer that's not helpful, if you don't want to up-vote it because you think it could be better, if you see a way to improve it, how about add a comment to criticize it?</p>

<p>At the moment when I see an answer with no up-votes and no comments, I can't tell the difference between:</p>

<ul>
<li>This might be a good answer but there's no-one competent enough to judge (up-vote) it</li>
<li>There are people competent to judge and they have decided that it was not worth up-voting</li>
</ul>

<hr>

<p>If you answer this question feel free to include personal answers: e.g. "yes, criticize my answers" or "no, don't criticize my answers" and/or "I do/don't like to criticize other people's answers".</p>

<p>I admit that criticism can seem dis-harmonious, and that SE is not intended for discussion/dialog.</p>

<p>OTOH some people post answers in public, not only to help others but in the hope that if their answer can be improved, someone will point that out.</p>

<p>See also <a href="https://buddhism.meta.stackexchange.com/q/107/254">Vote Early, Vote Often</a></p>
 43: <p>Re: voting, if you don't really understand an answer, do not vote.</p>

<p>Re: criticism, I only downvote and criticize an answer when I see the topic clearly enough that I can be <em>certain</em> that my understanding is complete and the answer is mistaken.</p>

<p>If you have only a vague understanding of the topic, and can't really follow the reasoning of the answer, but the answer seems to mismatch some postulates/axioms you have heard about, ask a new question!</p>
 254: <ol>
<li><p>If an answer is bad (useless or worse), then you <strong>should</strong> down-vote it <strong>and</strong> leave a comment. The comment is:</p>

<ul>
<li>To tell the person who posted it why it's down-voted, so that they can (if they wish) improve or delete their answer</li>
<li>To warn other readers that there may be something wrong, and specify what you think is wrong, so that they can judge for themselves.</li>
</ul></li>
<li><p>If you <strong>totally don't understand</strong> an answer then you can <strong>ask a separate question</strong>. If there's an expert answer which contains several complicated expressions, which were intended as an answer to the original question, it doesn't make sense to question those too much:</p>

<ul>
<li>Because comments aren't a suitable place for expert answers: asking a separate question allows room for one or more corresponding answers</li>
<li>Because changing the subject might detract from the original question and original answer</li>
</ul></li>
<li><p>If you see an answer you don't really like (which is "<a href="http://en.wikipedia.org/wiki/Meh" rel="nofollow">meh</a>"), make sure that a better answer exists even if <strong>you have to write that answer yourself</strong>. You can write a whole answer; or just write a partial answer, for example instead of asking someone to add to their answer, you could write, </p>

<blockquote>
  <p>In addition to the other answers, ...</p>
</blockquote>

<p>or</p>

<blockquote>
  <p>Further to so-and-so's answer, ...</p>
</blockquote></li>
<li><p>Comments to an answer are for minor conversation about that answer, between <strong>you</strong> and its author. You nearly understand something but not quite, or you're not sure? You think you understand, but maybe the answer can be worded in an alternative way? Then comment. The author can:</p>

<ul>
<li>Ignore the comment</li>
<li>Reply to the comment</li>
<li>Edit their answer</li>
<li>Flag the comment as unhelpful</li>
</ul></li>
</ol>

<p>About me:</p>

<ul>
<li>I like to comment occasionally, e.g. to verify whether I understand an answer</li>
<li>I hope I don't mind receiving comments on my answers</li>
<li>Feel free to delete any comments of mine if they are not or if they stop being useful</li>
</ul>
