Final answer:
Thomas Jefferson declared in the Declaration of Independence that every American has the unalienable rights to Life, Liberty, and the pursuit of Happiness. These rights are fundamental and must be protected by the government, with the provision that citizens may alter or abolish a government that fails to do so.
Step-by-step explanation:
The three rights Thomas Jefferson said every American is entitled to are Life, Liberty, and the pursuit of Happiness. The Declaration of Independence, which he authored, emphasizes these as unalienable rights—rights so fundamental that they cannot be taken away or denied. Influenced by the natural rights philosophy of John Locke, Jefferson articulated a vision of a government's purpose: to protect these essential freedoms.
The Declaration also underscores the point that if a government fails to safeguard these rights, its citizens have the authority to alter or abolish it, a radical concept at the time. This idea of a social contract between the people and their government forms a cornerstone of American democracy and reflects Jefferson's Enlightenment-influenced thinking. The mention of property as a right in some versions relates back to Locke's original triad of rights: "Life, Liberty, and Property." However, Jefferson chose to use "the pursuit of Happiness" in the final text of the Declaration.