Each post, we can click on a thumbs up icon, to show that we like/agree with the post but don't need to add anything in particular to the post ourselves.
So far so good.
So my suggestion is that we get a thumbs down icon added.
That way we can indicate that we don't like or don't agree with a post, without having to engage in a pissing match with the original poster, which usually degenerates into name-calling.