It has become necessary for the 13 colonies to separate from Great Britain. These 13 colonies have the right to become a nation as legitimate as any other nation. Additionally, it is important to explain to the public, including those in other nations, why this declaration of independence is being made.
This declaration is based on certain truths. All men are meant to be equal and to have certain rights ("unalienable rights") that the government should never take away. These rights include "life, liberty and the pursuit of happiness."
Governments exist to support the rights of men. Governments exist only through the power of the people that they represent. When a government fails to grant rights to the people and removes the involvement of the people, the people have the right to change their government in a way that will allow for their unalienable rights to be protected. Governments should not be overthrown for trivial reasons; it is not typical for people to change a system that they are accustomed to. However, when the people have suffered many abuses under the control of a totalitarian leader, they not only have the right but the duty to overthrow that government.
The Declaration of Independence is important because it inspired many revolutionary efforts throughout the world and contributed to Americans' understanding of their values as a new nation. The introduction, called the preamble, to the Declaration of Independence is especially important because it builds connections between philosophical theory and practical politics, expresses the fundamental values of the new American government, and also appeals to other nations to accept the new nation.
The introduction relies heavily on the philosophical and political ideas of the Enlightenment period of 18th century Europe, including the ideas of Thomas Hobbes, Jean Jacques Rousseau, and, most particularly, John Locke. Locke believed that humans, by nature, had the right to protection of life, health, liberty and possessions. Jefferson altered this slightly when he claims the unalienable rights include "life, liberty and the pursuit of happiness." Locke also strongly opposed the divine right of kings--which held that kings held absolute power because they were placed on their throne by God--and insisted that the people had the right to consent to their government and that the power of law making resides with the people. Jefferson included this theory when he writes "to secure these rights, governments are instituted among men deriving their just powers from the consent of the governed." Jefferson's declaration helped to put Locke's philosophies into the realm of real-world politics. Many revolutions that occurred after the American Revolution cited Jefferson's Declaration of Independence as justification in overthrowing a corrupt and dictatorial power.
The introduction to the Declaration of Independence also is important for the ways it contributed to Americans' understanding of their rights as citizens. Americans continue to believe that the phrase "all men are created equal" is a fundamental "law" in the country. While this phrase was included in the introduction to the declaration, it appears nowhere else in official documents defining rights granted under the U.S. Government. The Declaration of Independence holds no legal authority in our country, yet it continues to be cited as the foundation for American equality. Various groups throughout history have criticized American "equality", referring to the introduction of the declaration for support. Critics point to Jefferson's contradictory message regarding equality in reference to slavery. Although Jefferson stated that all men are created equal and have the right to liberty, he ran a large plantation and was a slaveholder. Other critics point to the use of the word "men" as excluding women citizens. The 1848 Seneca Falls Convention used Jefferson's format and style to draft The Declaration of Sentiments, a document declaring women's unfair treatment by the U.S. government and by society. Both as a source for debate about equality and as a definition of the ideological foundation of the new nation, the introduction to the Declaration played a crucial role in defining American values and laws.
The introduction is also significant because Jefferson insisted on the importance of explaining the rebellious actions of the 13 colonies to the nations and statesmen of the world. The most powerful nations of the world in the 18th century were monarchies. The ideas of Jefferson could serve not only to threaten Great Britain's colonial empire, but the colonial empires of other nations in Europe. Recognizing the importance of maintaining good diplomatic relations with European nations, Jefferson sought to explain the actions of the 13 colonies in rational terms. Anticipating that this document would influence rebellions elsewhere, Jefferson clarified that governments should not be overthrown for trivial causes. Instead, Jefferson explained that only "despotic" or totalitarian governments should be overthrown.