It's easy to find elements of both lines of thought. For now I'm going to disregard all interactions that are not state vs. state for the sake of simplicity. Specifically, I want to look at the realm of international trade and how nations regulate that trade.
Our group looked at the WTO, and I think it's a perfect example of how elements of both coercion and rational discourse are apparent in the system. First, the WTO started a bit like Hobbes' description of the Commonwealth. Member nations, through negotiation, voluntarily created a system that gave up some rights in exchange for a way to normalize trade between member states. The rights that were given up were not so extreme as what Hobbes described, but they are important. These rights include measures such as placing import bans and tariffs on products from other nations that do not conform to some standard in the importing country(environmental, health and safety, labor laws, etc.).
By giving up these rights, the member nations agreed to abide by rulings issued by a dispute resolution system. If a member state is found to not be in compliance with the agreed upon standards, they have three options. First, they can remove the disputed measure. Second, if they do not, they can provide compensation for measure. Third, if they do neither the state that brought the charges may retaliate in kind.
As you can see, there are some basic elements of coercion in the system. If all else fails, and two nations can not agree to a way to resolve the dispute, then attempt at raw coercive power is made. However, retaliation is rare.
So, in terms of trade relations between states, the answer is yes. Although rational discourse is the basis for agreements, some element of coercion will remain in place.
