Final answer:
The Declaration of Independence did not incorporate John Locke's idea of separation of powers; instead it focused on his concepts of natural rights, social contract, and consent of the governed. Separation of powers was more directly influenced by Montesquieu and would be later addressed in the US Constitution.
Step-by-step explanation:
Among John Locke's ideas, the one that the Declaration of Independence did not use is the concept of separation of powers. This concept, widely associated with the works of Baron de Montesquieu, refers to dividing government authority into legislative, executive, and judicial branches to prevent any one branch from gaining too much power. Locke's most direct contributions to the Declaration were the concepts of natural rights, the social contract, and consent of the governed. These ideas are famously reflected in the Declaration's assertion of unalienable rights of "life, liberty, and the pursuit of happiness" and the principle that governments derive "their just powers from the consent of the governed." The omission of separation of powers from the Declaration can be attributed to its purpose as an assertion of ideological principles and a proclamation of independence, rather than a detailed blueprint for governance structures, which would be later addressed in the US Constitution.