While this site isn't Reddit, absolutely anyone who's registered can down or upvote posts. This may include people who didn't evaluate the post, people who are below the sanity line we'd wish of members of LW, sock puppets and of course, even for a decent rationalist, some posts may still elicit a strong emotional response, upon which we may be tempted to act. Sometimes we won't even notice we did.

And for instance in the past two days I've seen quite a few posts downvoted because the people who made them weren't acting like we would expect rationalists would, or simply weren't nice and careful enough with their wording. I was tempted to upvote them on the idea that so long as such posts only represent a minority of the site's output, rationalists could just use that as information, and update on it. Interesting cases of muddled thinking and biases to learn from.

I decided against it since I noticed this was mainly a rationalization, that my main motivation was rooted my desire to "help" in what I emotionally perceived as a case of "injustice". On second thought I decided that the community's vote should in most case be better than my opinion, unless I had a concrete, real reason to the contrary.

I rarely upvote anything, and almost never downvote anyway. I use the first to push up ideas I find interesting. I don't usually find enough real good reasons to use the latter.

To get back to my point though, which are our safeguards against people operating multiple accounts, or who simply registered here without having a real idea of what was going on ?

The idea of not just voting, but also explaining why we choose one way or the other, seems interesting.