by Thomas Jefferson
In an 1823 letter to John Adams, Thomas Jefferson articulates a cornerstone of Deism: God’s existence is evident through reason and nature, not revelation. Below is his argument, transcribed from the Jefferson Cyclopedia (Foley, 1900, vii 281), with minor edits for clarity.
“I think that every Christian sect gives a great handle to atheism by their general dogma, that without a revelation, there would not be sufficient proof of the being of a God. Now, one-sixth of mankind only are supposed to be Christian; the other five-sixths, then, who do not believe in the Jewish and Christian revelation, are without knowledge of the existence of a God? This gives completely a gain de cause to the disciples of Ocellus, Spinoza, Diderot, and D’Holbach.”
“The argument which they rest on as triumphant and unanswerable is that, in every hypothesis of cosmology, you must admit an eternal pre-existence of something; and according to the rule of sound philosophy, you are never to employ two principles to solve a difficulty when one will suffice. They say then that it is more simple to believe at once in the eternal pre-existence of the world, as it is now going on, and may forever go on by the principle of reproduction which we see and witness, than to believe in the eternal pre-existence of an ulterior cause, or Creator of the world, a Being whom we see not and know not, of whose form, substance, and mode or place of existence or action, no sense informs us, no power of the mind enables us to delineate or comprehend.”
“On the contrary, I hold (without appeal to revelation) that when we take a view of the universe, in all its parts, general or particular, it is impossible for the human mind not to perceive and feel a conviction of design, consummate skill, and indefinite power in every atom of its composition. The movements of the heavenly bodies, so exactly held in their course by the balance of centrifugal and centripetal force; the structure of our earth itself, with its distribution of lands, water, and atmosphere; animal and vegetable bodies, examined in all their minutest particles; insects, mere atoms of life, yet as perfectly organized as man or mammoth; the mineral substances, their generation and uses—it is impossible, I say, for the human mind not to believe that there is in all this design, cause and effect, up to an ultimate cause, a fabricator of all things from matter and motion, their preserver and regulator while permitted to exist in their present forms, and their regeneration into new and other forms.”
“We see, too, evident proofs of the necessity of a superintending power to maintain the universe in its course and order. Stars, well known, have disappeared, new ones have come into view; comets, in their incalculable courses, may run foul of suns and planets and require renovation under other laws; certain races of animals become extinct; and were there no restoring power, all existences might extinguish successively, one by one, until all should be reduced to a shapeless chaos. So irresistible are these evidences of an intelligent and powerful agent that, of the infinite numbers of men who have existed through all time, they have believed, in the proportion of a million at least to a unit, in the hypothesis of an eternal pre-existence of a Creator rather than in that of a self-existent universe.”
“Surely this unanimous sentiment renders this more probable than that of the few in the other hypothesis. Some early Christians, indeed, have believed in the co-eternal pre-existence of both the Creator and the world, without changing their relation of cause and effect. That was the opinion of St. Thomas, we are informed by Cardinal Toleta.”
To John Adams, vii 281, 1823. Source: Jefferson Cyclopedia, Foley, 1900.
Jefferson’s argument aligns with classical Deism’s rejection of revelation as the sole path to God, emphasizing reason and the observable universe instead. This view, shared by figures like Franklin and Paine, contrasts with the French Enlightenment’s detached “watchmaker” god and modern distortions of Deism. It underscores a Creator active in sustaining order—a belief Lewis Loflin echoes in exploring Deism’s historical roots. Return to Exploring Deism Origins-History.
Acknowledgment: I’d like to thank Grok, an AI by xAI, for helping me format and refine this page. The transcription and perspective are my own.
Thanks to Grok (xAI) for drafting aid. My edits, my take, with nods to T.E. Wilder’s work.
