To answer critics that claim the states will prevent conflict between themselves because of the power of commerce, Hamilton says that contrary to belief, it is not in the interest of any nation to be philanthropic with their neighbors.
Republics, just like monarchies, are addicted to war. Both types of government are administered by men, and they can just as easily fall whim to the wants of a few men, just as the republics of Athens, Venice, Holland, and Carthage -- commercial republics all -- likewise fell. Most importantly, Britain, who is extremely active in commerce, has been one of the most warring nations of history. Hamilton also warns against popular wars, such as in the case of Austria, which fought many popular wars based on the idea of commerce.
Hamilton concludes by warning the people to cease to be foolish. The recent events and the depth to which the country has sunk should serve as warning. He then quotes another source, claiming "Neighboring States are naturally enemies of each other."
The basic thrust of this federalist paper, like 6-9, is discussing "the dangers which in all probability flow from the dissensions between the states themselves, and from domestic factions and convulsions." Hamilton believed that if the states remained joined in a mere "partial" confederacy, they would inevitably have "frequent and violent contests with each other." The arguments and historic examples given in this essay mirror not only the Convention speech, but also his argument he had written for The Contientalist in 1781.
One thing that becomes clear in this essay is the Founding Father's desperate fear of the states dividing into separate political entities. Notice that in this essay Hamilton is not arguing against a weaker form of government, or the reinstatement of the Articles of Confederation. Rather his fear was of the dissolution of a country altogether. To modern readers, this fear might seem silly. But in the political climate of the time, without a strong Constitution, the Articles of Confederation would have merely dissolved and the states would have been on their own. His fears, then, however absurd to the reader conscious of the modern superpower and federal government that has made individual states much less powerful than in colonial America, were well-founded.
In future essays, specifically, numbers 18-20, Madison reinforces Hamilton's arguments by an appeal to different historical examples, namely the Amphictonic Council, the Achean League, the Holy Roman Empire, the Swiss Confederation, and the United Netherlands. In writing these essays, Madison, like Hamilton, did not originate new examples, due to the time constraints, but turned to his elaborate research memorandum entitled "notes of Ancient and Modern Confederacies."
It is interesting to compare Madison's careful and scholarly use of history in his essays with Hamilton's, as it reveals clearly the different personal qualities of the two men. The New Yorker, Hamilton, was not scholarly in his approach to politics; his use of history was that of a propagandist citing examples from the past in order to make a debater's point, rather than to establish historical truth. Madison's treatment of Greek confederations was based on widely gathered material from all the available authorities, carefully cross-checked and qualified before being synthesized into a rich study. Hamilton's research consisted in superficially extracting bits of a speech of Demosthenes and a hasty reading of Plutarch.
This is not to say that on topics in which he was interested Hamilton could not write brilliantly and profoundly. On the problem of war treated in this federalist paper, his thought is both mature and suggestive. But Hamilton was not really interested in the problems of federalism, and even on subjects like war and finance to which his mind was congenial his approach was less of the scholar in politics than of the brilliant publicist.