First of all, voting is the main way for correct and useful articles to gain visibility on the site, and for incorrect articles to lose visibility. Dignitas is a collaborative website. Our collective wisdom is born through contributions from all users. We do not all have time to import statements and compose answers, but you can contribute to this process simply by voting.
Secondly, voting gives reputation to Dignitas users who constantly write correct and useful articles, which in turn gives them greater administrative privileges. Thus, the users who are the most passionate about the project and involved in it end up governing the site.
Anyone with a reputation of 15 can upvote, and anyone with a reputation of 125 can downvote.
Dignitas aims to separate truth from falsehood. But truths and lies must be recorded for posterity. If the statement is imported precisely, properly citing the source and with a legible formatting, it deserves an upvote regardless of whether it seems true or false. If you downvote statements that seem false, you will contribute to driving them into oblivion, which is a mistake.
Conversely, if the statement is imported inaccurately, without citing the source or with bad formatting, you can downvote it. If you want, it is more constructive to edit the statement to improve it, or at least to leave a comment with suggestions for improvement, than to just downvote.
For more serious defects (spam, insults, made-up statements) you can flag the statement.
Answers: Vote for correctness and completeness, regardless of whether or not you like the conclusion.
Even a broken watch shows the exact time twice a day. Even politicians who usually lie through their teeth tell the truth occasionally. Conversely, upright politicians can occasionally make mistakes. We urge you to vote the argument, not on its conclusion. Dignitas is not a site for partisan wars. It is a site for determining the truth value of statements.
When you vote for an answer, ask yourself: Is it well structured? Does it support its claims with credible external links? Is it fluent? If so, upvote it. If not, downvote it. In intermediate cases, do not vote at all. If you have suggestions for improvement, leave a comment or suggest a change.
Do not vote just to thank the author for the time spent writing the answer. A confusing or downright incorrect response is not worth promoting, no matter how long it took to compose, especially if its author is unwilling to heed the constructive feedback from the comments.