I think @oothenigerian's point is that downvoting comments simply because they express a contrarian view is bad form.

It requires a certain level of maturity, introspection, humility and openness to not simply tag opposing views as pointless and therefore worthy of a downvote.

Another way to express it is this - is it possible to upvote a comment that you disagree with? i.e. simply on the ability of the author to substantiate his points?

Perhaps we should introduce transparent algorithmic voting.

Hmmm....