(I assume that you mean the comments, though the upvote/flag on a top-level item can be similar.) I can upvote (or downvote) for content that I agree/disagree

(I assume that you mean the comments, though the upvote/flag on a top-level item can be similar.) I can upvote (or downvote) for content that I agree/disagree with as well as how much the comment does/doesn't contribute to the debate, as you suggest. Sometimes those are finely enough balanced for me not to do either! I tend to reserve downvotes for things that are inflammatory or shallow or dishonest or similar.