This section, consisting of six papers (Chapters 9–14), discusses the advantage of union in general, and not the advantages of a particular form of union as set forth in the proposed constitution.
A firm union acts to prevent domestic faction and insurrection. A reading of the histories of the petty republics of Greece and Italy caused such "sensations of horror and disgust at the distractions with which they were continually agitated" that advocates of despotism had drawn arguments not only against all forms of republican government, but against the very principles of civil liberty.
"The science of politics, however, like most other sciences has received great improvement . . . not known at all, or imperfectly known to the ancients," said Hamilton, who went on to quote at length from the great French political philosopher, Montesquieu, whose Spirit of the Laws had become a classic.
Extracting from this work what suited his argument, Hamilton cited Montesquieu on the advantages of what the latter called a "Confederate Republic, . . . a kind of assemblage of societies, that constitute a new one, capable of increasing by means of new associations, till they arrive to such a degree of power as to be able to provide for the security of the united body. A republic of this kind, able to withstand an external force, may support itself without any internal corruption." The American republic, if placed under the proposed constitution, would answer that description.
The disquisitions here by Hamilton on the weaknesses of the petty republics in ancient Greece and Italy were not good history, being rather superficial, but made good argument for the large Federalist plan of government he favored. Hamilton was also rather partisan in the passages he chose to quote from Montesquieu's Spirit of the Laws.