> OR what if there were downvotes as well as up?

Downvotes can be abused for undermining people's thought you disagree on.

Instead, provide a way to "counter-argument", which if upvoted, will count as downvote to the parent argument.

This will enable people to "rob" votes of swing voters from the parent argument to the counter-argument

Also, hint: you might want to separate those questions above d with double line endings