After Jefferson developed the American philosophy behind equality, liberty, and government by consent, he finally began the primary purpose for the writing of the Declaration: to explain to the world why America chose to separate from Great Britain.
He conceded that such action should not be taken without careful consideration:
“Prudence, indeed, will dictate that Governments long established should not be changed for light and transient causes; and accordingly all experience hath shewn that mankind are more disposed to suffer, while evils are sufferable than to right themselves by abolishing the forms to which they are accustomed.”
Jefferson characterized British policies regarding the colonies, however, neither "light" nor "transient.” Americans had enjoyed a great deal of autonomy in the relations with Britain. Because of what Parliamentarian Edmund Burke described as a “wise and salutary neglect” by the mother country, Britain's North American colonies had grown prosperous. In addition, they had enjoyed a great deal of autonomy and local self government through their colonial legislatures. After the end of the French and Indian War in 1763, however, Britain embarked on a systematic effort to tighten their control over the colonies through new regulatory and tax initiatives.
The colonists interpreted these initiatives as omens of something much more sinister. From their widespread reading of polemical writing from radical Whigs in Britain, Americans became predisposed to see in British actions a conspiracy of power against liberty. Edmund Burke, a friend of the colonies, warned his fellow representatives in Parliament of the “fierce spirit of liberty” among Americans and that they “auger misgovernment at a distance and sniff the approach of tyranny in every tainted breeze.”
Jefferson confirmed Burke's insight into the perspective of the colonists in the next section of the Declaration. He drew a conclusion, however, that Burke could not share: although they did not live under a tyranny, they believed they saw one in the making.
“But when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security. Such has been the patient sufferance of these Colonies; and such is now the necessity which constrains them to alter their former Systems of Government. The history of the present King of Great Britain is a history of repeated injuries and usurpations, all having in direct object the establishment of an absolute Tyranny over these States. To prove this, let Facts be submitted to a candid world.”
Then follows the great body of the Declaration: the charges against the the king. Many of these charges only repeated what Jefferson already had leveled at the king in his A Summary View of the Rights of British America (1774). He had written this to express the views of the colony of Virginia regarding the imperial crisis. Some additional charges came from other petitions and protests originating from other local assemblies in the colonies over the previous decade.
So why blame the king for the actions taken by Parliament?
He probably blamed the king because by this time the colonists had rejected Parliamentary sovereignty over them. Americans had come to conceive of the British Empire as much like the British Commonwealth of Nations today: each province with its own lawmaking body but united by ties with the British monarchy. They blamed him because he cooperated in Parliament's attempt to subject the colonists to its authority. Americans showed prudence and patience in their appeals, protests, and boycotts. In response, the Parliament continued to subject the colonies to their tax and regulatory powers.
“In every stage of these Oppressions We have Petitioned for Redress in the most humble terms: Our repeated Petitions have been answered only by repeated injury. A Prince, whose character is thus marked by every act which may define a Tyrant, is unfit to be the ruler of a free people.”
Even the British public appeared deaf to their appeals. Under such circumstances, the only course of action possible by the colonists was independence. Jefferson described it as he did in the opening paragraph of the Declaration: one of necessity.
"Nor have We been wanting in attentions to our British brethren. We have warned them from time to time of attempts by their legislature to extend an unwarrantable jurisdiction over us. We have reminded them of the circumstances of our emigration and settlement here. We have appealed to their native justice and magnanimity, and we have conjured them by the ties of our common kindred to disavow these usurpations, which would inevitably interrupt our connections and correspondence. They too have been deaf to the voice of justice and of consanguinity. We must, therefore, acquiesce in the necessity, which denounces our Separation, and hold them, as we hold the rest of mankind, Enemies in War, in Peace Friends."
Jefferson's rhetorical reached a crescendo at last with the incorporation into the Declaration of Richard Henry Lee's resolution for independence passed by Congress on 2 July 1776.