The late 17th and early 18th century English philosopher John Locke was one of the first to articulate ideas central to democratic governments. These include concepts like natural laws, consent of the governed, religious tolerance and the legitimate overthrow of a government. All these ideas were applied by the framers of the United States Constitution in the 18th century.

Natural Rights

One of John Locke's central theories was that all men are entitled to natural rights. These natural, God-given rights include rights to life, liberty and property. In his "Second Treatise of Government," Locke articulated his belief that the purpose of government was to protect these fundamental rights. In the 18th century, these ideas were enshrined in the United States almost word-for-word, when Thomas Jefferson declared that all men "were endowed by their creator with certain inalienable rights that among these are life, liberty and the pursuit of happiness." Jefferson substituted "property" for "pursuit of happiness."

Consent of the Governed

John Locke believed that no government was legitimate if it did not rule with the consent of the governed. Locke's philosophy begins by describing a state of nature without a government. In this state, people come together and consent to form a government for the protection of their property. This theory of consent is a cornerstone of democratic government. In the United States, the opening line of the U.S. Constitution, which uses the subject "We the People," clearly articulates a government based on Lockean principles of consent.

Religious Tolerance

Locke's second major work was his "Letters Concerning Toleration." In these essays, Locke articulated the reasons why governments should not persecute minority religious groups, like Quakers or Anabaptists. While Locke articulated opposition to certain religious groups -- including Catholics and Quakers -- he did not believe it was just for a government to interfere with their natural rights, no matter how abhorrent their beliefs were. The American Bill of Rights follows Locke by forbidding the creation of any law that impedes on a person's ability to freely practice his religion.

Overthrowing Illegitimate Government

The United States might not have its political independence without the ideas of John Locke. Locke believed that people had a natural right to overthrow a government that did not protect their natural rights. When the British Parliament refused to give Americans representation in Parliament and taxed their property, Americans declared independence from Britain. This was perfectly consistent with the ideas of John Locke, because the American people reserved the right to overthrow an unjust government like Britain's.