Whether or not Congress can find a way to authorize military force against ISIS is actually more interesting than whether they should or not. Because, if Congress is simply incapable of authorizing force, not because they don’t want to but because they’re incompetent, then they can’t really fulfill that constitutional role. And it will be taken away from them by necessity.
You can argue that this role has already been taken away from them, and, to a degree, it has.
What’s different this time is that we’re on the verge of reaching the point where most people will have to agree that that’s a good thing.
It would be different if Congress refused authorization because they opposed the use of military force. That’s their prerogative. That’s what they’re supposed to decide.
This is an example of them not being able to authorize force that they do support because they hate and mistrust each other and the president too much.
Our republic depends on a functionality that no longer exists.