Straight from today’s Quotle — here’s who really said it, and the story behind it. Play again

Who really said it

You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe

Not Carl Sagan — no source in anything he wrote Unknown Origin unidentified · no work, page, speech or date has ever been produced
Disputed Rights unconfirmed

Wikiquote files this sentence in its Misattributed section for Carl Sagan ↗, noting that it is “Sometimes attributed to Contact (1985), but the quote does not appear in that book,” and that it shows up credited to Sagan in Judson Poling’s 2003 study guide Do Science and the Bible Conflict? — but “without source.” We also searched the full text of The Demon-Haunted World (1995) on the Internet Archive ↗, the obvious place for a Sagan line about credulity, and found no instance of “convince a believer,” “need to believe” or “deep seated.” The thought is very much in Sagan’s register; the sentence is not documented anywhere in his work.

Last verified 10 Aug 2026 · how we verify · spot an error?

For presentations

Put it on a slide

Disputed credit — copy with the correction

“You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe” Not Carl Sagan. No source has ever been produced for "You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe." Wikiquote lists it under Misattributed for Sagan, notes it is not in his novel Contact (1985), and cites only an unsourced appearance in Judson Poling's Do Science and the Bible Conflict? (Zondervan, 2003). A full-text search of The Demon-Haunted World (1995) finds no match. The documented ancestor of the idea is Jonathan Swift, 1721. — Quotle.info

The slide-ready mistake: crediting this to Carl Sagan. Use the credit shown above instead.

Can you use it?

We couldn’t verify where this wording comes from, so there’s no rights status to give. Safe to present as an unverified or anonymous line — just don’t assert a specific author or source.

Image direction — grounded in this quote’s real context; paste into your image tool

In context

Evoking the themes of truth, doubt and knowledge. Theme: "You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe". Atmospheric and restrained, cinematic directional light, a muted period-appropriate palette, fine grain and texture. Compose with generous empty space for the quote and a small credit line. No lettering in the image itself.

Minimalist

Minimalist editorial slide for the quote "You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe". Clean background, a single muted accent color, generous negative space, subtle paper or linen texture, no literal illustration — let the words carry it. Reserve clear space for a serif quote and a small credit line. No lettering in the image itself.

Provenance

The source that isn’t

Popularly credited
Carl Sagan — with no work, page or date attached
Book usually named
Contact
Checked against
The Demon-Haunted World (1995), full text — no match for any distinctive phrase
Attributed in print by
Judson Poling, Do Science and the Bible Conflict? (Zondervan, 2003), credited to Sagan without a source

You can’t convince a believer of anything; for their belief is not based on evidence, it’s based on a deep seated need to believe. No known source

There is no fuller context to show, because there is no located source text. Every version of this line online is the same free-floating sentence, always with Sagan’s name and never with a citation — the classic signature of an attribution that was never checked.

Carl Sagan on Wikiquote — Misattributed section

How we verified this

  • 1985 — Contact, Sagan’s only novel, is published by Simon and Schuster (Wikipedia ↗). It is the book most often named as the source of this line. Wikiquote records ↗ that the quote does not appear in it.
  • 1995 — Sagan publishes The Demon-Haunted World: Science as a Candle in the Dark, an entire book about why people believe unevidenced things. Searching the full text on the Internet Archive ↗ returns nothing for “convince a believer,” “need to believe” or “deep seated.”
  • 2003 — the line appears credited to Sagan, without any source, in Judson Poling’s Zondervan study guide Do Science and the Bible Conflict?, the print attribution flagged on Wikiquote’s Misattributed list ↗ (Google Books record ↗; the preview does not display the page text).
  • 2022 — Cornell’s own Carl Sagan Institute publishes an essay on Sagan misattribution ↗, built around a different fake (“Somewhere, something incredible is waiting to be known”) and one diagnostic question: is it likelier that Sagan said something thousands of people cannot source, or that he never said it?

No rights status can honestly be asserted for this sentence. It has no identified author, no source work and no first publication, so there is nothing whose copyright term could be measured. Carl Sagan’s actual books — Contact (1985) and The Demon-Haunted World (1995) among them — are firmly in copyright, but neither contains this line.

Rights status is our research, not legal advice — and copyright varies by country and edition. For commercial or published use, confirm with the rightsholder. See terms.

Fact-check

A skeptic’s line with nothing to check it against

This sentence has been hung on Carl Sagan for decades, in three different ways — a named book, an assumed book, and a bare byline. None of them survives a look.

Contact (1985) Not in the text

Sagan’s only novel, published by Simon and Schuster (Wikipedia ↗), is the source most often cited. Wikiquote states flatly ↗ that the quote does not appear in that book.

The Demon-Haunted World (1995) No match

The natural guess, since the whole book is about belief without evidence. But a search of the full text on the Internet Archive ↗ finds no “convince a believer,” no “need to believe” and no “deep seated” anywhere in it.

Judson Poling, Do Science and the Bible Conflict? (2003) Unsourced

The print appearance Wikiquote flags ↗: a Zondervan small-group study guide that prints the line under Sagan’s name and gives no citation for it. A quote passed on without a source is not evidence of a source.

Jonathan Swift The real ancestor

The thought — that argument cannot dislodge a belief argument never installed — is old and well documented. Quote Investigator traces it ↗ to Swift in 1721: “Reasoning will never make a Man correct an ill Opinion, which by Reasoning he never acquired.” That page does not mention Sagan at all.

The honest position: no work, no page, no speech, no date. Wikiquote classifies it as misattributed to Carl Sagan ↗, and nothing we could fetch contradicts that.

Context

Why this one sticks to Sagan so well

Fake quotes travel on plausibility, and this one is extremely plausible. Sagan spent the last decade of his life arguing that belief is often emotional infrastructure rather than a conclusion — and he said so in sentences he did write. In The Demon-Haunted World he describes hoaxers demonstrating on camera exactly how they made crop circles, and notes that believers were unimpressed and simply argued there were too many circles for two men with a board and a rope. That is the same observation, made concretely, with a source you can open.

The manufactured version is punchier, more absolute and more flattering to whoever is repeating it, which is precisely why it outran the real thing. It also gets the argument slightly wrong: Sagan’s point was that all of us, himself included, want to believe things — he wrote about how badly he wanted his dead parents to have gone somewhere — not that “believers” are a separate category of person immune to evidence. Attaching a sneer to a man who spent a career refusing to sneer is the real cost of the misattribution.

Which is likelier — that Sagan said something thousands of people cannot source, or that he never said it at all?

The Cornell test, and the idea’s real ancestor

The Carl Sagan Institute at Cornell published an essay on this exact problem in July 2022, prompted by NASA Administrator Bill Nelson quoting a Sagan line at a James Webb Space Telescope event. The line — “Somewhere, something incredible is waiting to be known” — was written by Newsweek reporter Sharon Begley about Sagan, not by Sagan. The essay’s test is the one to apply here: when no one can produce a page number, the absence of a page number is the finding.

There is a genuine, documented lineage for the thought, and it is a great deal older than Sagan. Quote Investigator traces it to Jonathan Swift in 1721, and follows the familiar modern paraphrase — you cannot reason a man out of a thing he was never reasoned into — through the nineteenth century. If you want to quote the idea and be safe, quote Swift.

Explore

Filed under

More provenance-checked quotes on the same theme, each with its reuse status.

Truth Doubt Knowledge

Go further

Dig deeper

Trusted places to keep pulling the thread — primary archives, fact-checks, and scholarship. We show how we used each one before you leave.

Carl Sagan — Wikiquote (Misattributed)en.wikiquote.org

The anchor. Lists this exact sentence under Misattributed, notes it is not in Contact (1985), and points to the unsourced 2003 print attribution.
The Demon-Haunted World — full textarchive.org

Searchable scan of Sagan’s 1995 book on credulity and skepticism. Check it yourself: the distinctive phrases of this quote are not in it.
Misattribution will often carry us to quotes that never werecarlsaganinstitute.cornell.edu

Cornell’s Carl Sagan Institute on why fake Sagan quotes spread. Concerns a different line, but sets out the test that sinks this one.
You Cannot Reason People Out of Something They Were Not Reasoned Intoquoteinvestigator.com

The documented ancestor of the idea, traced to Jonathan Swift in 1721. Quote Investigator has no article on the Sagan wording and does not mention him here.
Contact (novel)en.wikipedia.org

Publication record for the 1985 Simon and Schuster novel routinely named as this quote’s source.
Do Science and the Bible Conflict? — Judson Polingbooks.google.com

Google Books record for the 2003 Zondervan study guide Wikiquote cites as carrying the line credited to Sagan with no source. The preview does not show the page text.

Popularly credited author

Carl Sagan

Carl Sagan

1934–1996 · American astronomer, planetary scientist & science communicator, Cornell University

Carl Sagan was an American astronomer and planetary scientist at Cornell University, and the most effective science communicator of his generation — the presenter and co-writer of the 1980 television series Cosmos and the author of The Dragons of Eden, Pale Blue Dot and the novel Contact. His last major book, The Demon-Haunted World: Science as a Candle in the Dark (1995), is a sustained argument about why people believe unevidenced things and how to reason your way out. That book is exactly why this quote sticks to him — and exactly why its absence from it matters.

For writers & researchers

Cite this

No source work — attribution unsupported

No source work has been identified. Wikiquote’s Misattributed section for Carl Sagan records the line as appearing, credited to Sagan without a source, in Judson Poling, Do Science and the Bible Conflict? (Grand Rapids, MI: Zondervan, 2003); it also notes the line is sometimes attributed to Sagan’s novel Contact (New York: Simon and Schuster, 1985) but does not appear in that book. A full-text search of The Demon-Haunted World: Science as a Candle in the Dark (1995) on the Internet Archive returns no match.

This verification page

Quotle.info. “Who really said ‘You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep seated need to believe’?” Last verified 10 Aug 2026. https://quotle.info/who-said/you-cant-convince-a-believer-of-anything-for-their-belief/

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