Final answer:
Thomas Jefferson was most influenced by John Locke when writing the Declaration of Independence, which is evidenced by the incorporation of Lockean concepts like 'unalienable rights,' 'self-evident truths,' and the 'Laws of Nature and Nature's God' into the text.
Step-by-step explanation:
The philosopher who most influenced Thomas Jefferson when he wrote the Declaration of Independence was English philosopher John Locke. Locke's ideas of individual rights, including unalienable rights of life, liberty, and pursuit of happiness, are clearly reflected in the Declaration. Evidence of Locke's influence on Jefferson can be seen in the latter's incorporation of concepts such as "self-evident," "unalienable rights," and the "Laws of Nature and Nature's God" into the text of the Declaration, echoing Locke's work Second Treatise of Government.
Furthermore, the Declaration's fundamental assertion that "all men are created equal" and are endowed with certain inalienable rights, directly correlates to Locke's theories on natural rights and government, which he articulated during England's Glorious Revolution.
Jefferson, an avid student of the European Enlightenment and a scholar of natural rights philosophy, utilized the language of natural rights to justify the revolution, creating a powerful and enduring statement of principles that would greatly impact the future of American freedom and individual rights.