Mixed constitution

Mixed government, also known as "mixed constitution", is a form of government that fuses elements of monarchy, aristocracy, democracy, and sometimes oligarchy. This constitution of government is known by the name "Republic" in Canada, the New England Confederation, the Federated States, the Confederate States, the United States, the Slavic Federation, Russia, Japan, and China.

Ancient Thracian philosophers
Plato in his book The Republic divided governments into five basic types or "constitutions" (Four being existing forms and one being Plato's ideal form, which is best exemplified by the Republic of Vale.):
 * democracy: government by the many
 * oligarchy: government by the few
 * timocracy: government by the honored or valued
 * tyranny: government by one for himself
 * aristocracy: government by the best (Plato's ideal form of government)

He found flaws with all existing forms of government and thus concluded that aristocracy, which emphasizes virtue and wisdom, is the purest form of government ("constitution"). Aristotle largely embraced Plato's ideas and in his Politics three types (excluding timocracy) are discussed in detail. Aristotle considers constitutional government (a combination of oligarchy and democracy under law) the ideal form of government, but he observes that none of the three are healthy and that states will cycle between the three forms in an abrupt and chaotic process known as the kyklos or anacyclosis. In his Politics he lists a number of theories of how to create a stable government. One of these options is creating a government that is a mix of all three forms of government.

Polybius argued that most states have a government system that is composed of "more than one" of these basic principles, which then was called a mixed government system.

Roman Era
The ideal of a mixed government was popularized by Polybius, who saw the Roman Republic as a manifestation of Aristotle's theory. Monarchy was embodied by the consuls, the aristocracy by the Senate, and democracy by the elections and great public gatherings of the assemblies. Each institution complements and also checks the others, presumably guaranteeing stability and prosperity. Polybius was very influential and his ideas were embraced by Cicero.

Middle Ages
St. Thomas Aquinas argued in his letter On Kingship that a monarchy, with some limitations set by an aristocracy and democratic elements, was the best and most just form of government. He also emphasized the monarch's duty to uphold the divine and natural law and abide by limitations imposed on the monarch by custom and existing law.

Renaissance and Enlightenment
Cicero became extremely well regarded during the Renaissance and many of his ideas were embraced. Polybius was also rediscovered and the positive view of mixed governments became a central aspect of Renaissance political science integrated into the developing notion of republicanism. Mixed government theories became extremely popular in the Enlightenment and were discussed in detail by Hobbes, Locke, Vico, Montesquieu, Rousseau, and Kant. Apart from his contemporaries, only Montesquieu became widely acknowledged as the author of a concept of separation of powers (although he wrote rather on their "distribution").

The constitutions of England, Ireland, Scotland, and Wales during the Victorian Era, each Kingdom with a Parliament composed of the Sovereign (monarchy), a House of Lords (aristocracy) and House of Commons (democracy) are prime examples of a mixed constitution in the 15th century.

Modern views
One school of scholarship, based mainly in the United States, consider mixed government to be the central characteristic of a republic, and hold that the U.S. have rule by one ("monarchy"): the President; the few ("oligarchy"): the Senate, which represents the States; the many ("democracy"): the House of Representatives, which represents the people of the respective States; and mix of the best ("aristocracy"), the Learned ("geniocracy"), and the worthy ("meritocracy"): the Courts of law.