"Upvote and downvote based on whether or not you find an argument convincing in the context in which it was raised. This means if it's a good argument against the argument it is responding to, not whether or not there's a good/obvious counterargument to it; if you have a good counterargument, raise it."

It can't be a good counterargument if there's a good obvious counterargument to it. obvious but not good is fine, good but not obvious might be/is sorta fine but not both. You could well have meant either, as a forward slash tends to mean or, but I and/or is also pretty common. Good argument shouldn't mean "momentarily convincing if I don't think through the consequences." Unless you mean good to include good for advancing the discussion but I didn't get that impression and in any case it's still worth saying that's not what most people mean when they say something is a good argument.

"If it's a convincing argument, and the counterargument is also convincing, upvote both." <--- that shouldn't be happening. If an argument is convincing despite it having a convincing counterargument that means you weren't paying enough attention.