Users can turn on "showdead", which will allow them to see all comments (and upvote them, if necessary). In general, disagreeing is just fine; one can do so in

Users can turn on "showdead", which will allow them to see all comments (and upvote them, if necessary). In general, disagreeing is just fine; one can do so in a polite way. Being a 'jerk' usually entails disagreeing and being vitriolic about it. (An example of this is insulting the person rather than addressing why one disagrees with the arguments in the comment itself.)