It was generally agreed that the objects of the union could not be secured by any system founded on the principle of a confederation of sovereign states. a voluntary observance of the federal law by all the members, could never be hoped for.

in this passage, madison discusses the decision to write a new constitution.

madison suggests that the states

were anxious to work together.
preferred to not form a confederation.
would not cooperate with each other voluntarily.
would never agree to voluntarily obey any laws.