We didn't have an alliance with France/Britain before WWII broke out. It was 2-3 years before we entered that war for the simple reason we weren't in an alliance that predetermined if we entered or not. We had the luxury of observing and seeing if it was something we wanted to get involved in; if it was in our best interest. As far as the Pacific theater goes, we were dragged into that...no alliance caused us to enter that one either. Actually, I believe you could make an argument that alliances only escalate wars (WWI), for better or worse.
I think what Ron Paul is against are alliances that get us stuck in wars we might not want to be in or should be in. I think there is a difference.
With all that said, I would say I'm highly suspicious of alliances, but not necessarily against them.