From the article: "At what karma level can I downvote articles ? There is no karma level that I know of that will allow you to downvote articles." and "What

From the article: "At what karma level can I downvote articles ? There is no karma level that I know of that will allow you to downvote articles." and "What [karma] does give you is that at some point you can downvote other comments and it gives you the ability to flag posts." In other words, you can't downvote articles, ever, and you can downvote comments after a certain karma threshold has been reached.