John Adams (1735–1826), the second President of United States, was a representative theorist of the British North American Colonies and is known as the American Revolution’s most famous leader. He had been the only president to not be reelected until his son, John Quincy Adams (1767–1845), the sixth president, lost to Andrew Jackson (1767–1845). Therefore, one can appropriately say that almost historians have studied why the elder Adams had been unpopularity.

In The Creation of American Republic 1776–1787 (1998), Gordon Wood memorably appraised Adams’s significance in the chapter “The Relevance and Irrelevance of John Adams.” He portrayed Adams as “relevant” based on his earliest writings and his role in establishing the essential forms of American Constitutionalism such as a bicameral legislature, with independent executive and judicial branches, to promote effective checks and balances. However, Wood believed that Adams’ theory of government was incapable of adapting to changes in the American society after the 1780s because his ideas had been based on the ancient concept of mixed government, therefore, his countrymen started considering him an anachronistic aristocrat, thus reflecting his “irrelevance” in American democracy.

The Three-volume A Defence of the Constitutions of Government of the United States of America, published from 1787 to 1788, describes Adams’ constitutional theory. This publication had been initially accepted as a supreme achievement of American enlightenment because of Adams’ early fame and reputation. Nevertheless, several scholars eventually expressed their reservations with his thinking. For example, Mercy Otis Warren (1728–1814), in The Rise, Progress, and Termination of the American Revolution (1805), accused Adams of adopting corruptible European courts, therefore dismissing Republican principles. John Taylor (1753–1824), in An inquiry into the Principles and Policy of the Government of the United States (1814), criticized Adams’ theory, especially its aristocratic element. These insights on John Adams were echoed by pre-Wood historians such as Edward Handler, and John R. How Jr.. However, the difference between these historians and Wood is that formers believed that John Adams changed his stance after the American Revolution, while the latter thought that Adams’ political inclination had already been different from that of his colleagues and countrymen, and that this had already been revealed in the political and social processes of the 1780s.

On the basis of previous studies, this article illustrates that Adams’ political thought in Defence and its fourth volume, Discourses on Davila(1790–1791), had taken exception to the democratization of Republicanism in the American political society after the 1780s. It also shows how Adams’ “mixed government theory” was different nature from mixed government theory in the context of medieval Europe despite his use of old-fashioned terms, and this has been reflected in the American society since the colonial age. By describing the Americanistic nature of his “mixed government theory”, this article ascertains the changing process from the early modern to the modern age of American republic.

The American people revolted against British Empire policies to govern the American colonies in a more civilized and peaceful way by an effective government. With the successful independence, however, the United States of America needed to join the moral community of the sovereign states as Carl Schmitt called Jus Publicum Europaeum. In 1823 the Monroe Doctrine worked as an American manifesto to be independent from European morals.

The United States of America had to establish herself as a treaty-worthy nation in the Jus Publicum Europaeum by fulfilling international duties. For that purpose the United States as a sovereign state was required to accomplish the national unity defeating any independent authorities and rebellious groups within their land. In addition to that, the American government was expected to govern the people, following the civilized standard to keep the peace and order based on reasonable rules of law despite their burning pioneer spirit. The establishment of the Federal Constitution had given her a foundation of a full membership of the Jus Publicum Europaeum. But the fragile republic was not yet able to control their northwestern and southern territories against the British Empire, the Spanish Empire, and the native nations such as Seminole, Creek or Shawnee.

The fact that the United States actually concluded the Jay Treaty with Great Britain and resolved the quasi-war against France proved her treaty-worthiness. To the United States the War of 1812 made the final test of independence and dignity in the international community. The Treaty of Ghent and the victory at New Orleans confirmed the United States position in the powers and assured the national unity so that European states respected the American sovereignty to sever the friendly relationship with and military supports to the Indian nations. Shutting out foreign involvements, the Americans moved rapidly westward, destroying and removing the native people as they had intended at the time of the Revolution.

European powers’ recognition of the United States as an equal partner brought her a favorable position in the US-Spanish negotiation to settle Florida, Louisiana, and the Northwest territories to be a successor to the Spanish Empire. The Transcontinental Treaty set the United States the central figure in dealing with the problems of the land appropriation in the Northwestern territories and of the independence movements in Spanish American colonies.

With these successes and confidence the President James Monroe’s annual message made the audacious doctrine to Europe: European non-colonization and non-involvement of Americas, and American disentanglement from Europe. Even though the doctrine was a radical challenge to the European principles of the international relationship, it did not necessitate the United States any actions. The actual situations including independence movements in the Western Hemisphere urged little European involvements. Without responding to immediate necessities the doctrine could turn into a manifesto to extoll the superiority of the American System independent from the Jus Publicum Europaeum. The manifesto authorized, and praised the American liberty of rugged individualism.