Sean Carroll

On 21 February 2014, at a Baptist seminary in New Orleans, a cosmologist from Caltech stood opposite the Christian philosopher William Lane Craig to debate whether modern cosmology gives any reason to believe in God.¹ Before he went, Sean Carroll wrote on his blog that his aim was not to win but to say things that were true and understandable; in some corners the consensus was that he would be crushed.² Craig opened by arguing that contemporary cosmology makes God's existence considerably more probable than it would otherwise be, while denying that it proves anything.³⁴ Carroll answered that cause and effect are not the vocabulary of fundamental physics, that a complete and consistent model of the universe is all that can be asked of it, and that our metaphysics has to follow our physics.⁵⁶

This chapter asks how a boy from a family of steelworkers, who went to church every Sunday, came to argue in a seminary that the universe needs no God, and why he then lost interest in arguing about it.

A mild childhood

He was born on 5 October 1966 and grew up in Levittown and then Yardley, in Bucks County, Pennsylvania, near Philadelphia.⁷⁸ His was a family of steelworkers: both grandfathers worked for U.S. Steel, and his mother was a secretary there. His parents divorced when he was six, his father largely left the picture, and his mother raised him in a household that was politically conservative.⁸⁹

When he was very young the family went to church every Sunday. The church was Episcopalian, and he has since described it as a declining parish with a few dozen people, which he places in Trenton, New Jersey, across the river from Yardley.^10111213 He has called his religious experience always fairly mild: he was never repulsed by the church and never drawn to it, and the best part of Sunday was the pancakes afterwards.¹⁰¹⁴ He was, he has said, a believer, such as it was.¹⁵ On the belief timeline, this is where his faith sits, and it is a faint mark.

The church-going ended when he was about ten, when his mother's mother died. The family had been going, he has said, for her benefit.¹⁰ In the same year he read library books about black holes, quarks and the Big Bang and decided to be a physicist. He tells the two stories side by side and links neither to the other.¹⁶

Many little things

Nothing happened next, and that is the point of his story. By his own account he drifted away from belief very gradually, through junior high, high school and college, becoming clearer with time about an atheist point of view. He was not born an atheist, he said in 2017, and no single experience pushed him; such ideas, he has said, are put into the mind by many little things.¹⁵¹¹¹⁷

He chose Villanova, a Catholic university near home, because it offered him full tuition on merit; he would have gone to Harvard if he could.¹⁸ He took the required religion classes and enjoyed them, and the required philosophy led him to six semesters of it and a minor.¹⁹ What flicked the switch, he told an interviewer in 2021, was music. At Villanova he heard Emerson, Lake and Palmer's song "The Only Way (Hymn)", from the 1971 album Tarkus, and for the first time met the idea that a person could not only be an atheist but be happy and proud about it. That, he said, was the moment it crystallised, and the first time he said that he was an atheist.²⁰²¹ He gives no year. His college years can only be inferred, from his 1993 doctorate and a paper he published in 1990, as about 1984 to 1988.²²

On the timeline, his doubt sits here, in his college years, and not at the age of ten when the church-going stopped, because he describes no crisis and no date. The loss was a drift that began in childhood, and the song at Villanova is the first moment he names, the point at which an unbelief he had not examined became one he would say aloud. The timeline marks it as inferred, because no source dates it.²⁰¹⁷

A physicist first

He took his doctorate in astronomy at the Harvard-Smithsonian Center for Astrophysics in 1993, under George Field, then held postdoctoral posts at MIT and at Santa Barbara, and joined the faculty of the University of Chicago.²² His unbelief cost him nothing there. Atheism, he has said, is fairly uncontroversial in physics departments. His friend Don Page, a leading cosmologist and a born-again evangelical, talks about God in his lectures, and everyone nods along.²³

The intent to say something in public came early. At Chicago, in about 2000, an editor from the Free Press knocked on his door looking for a book. Carroll told him that the world had enough books about cosmology and needed one that said God does not exist. The publisher declined, because nobody knew who he was. Six years later Richard Dawkins's The God Delusion sold hugely, and the same editor, by then at another house, became Carroll's own.²⁴

The paper for Notre Dame

His first public argument was a paper for a conference on God and physical cosmology at the University of Notre Dame in January and February 2003, published two years later in the journal Faith and Philosophy under the title "Why (Almost All) Cosmologists Are Atheists".²⁵ Its case was modest in form. Science and religion, he wrote, are not incompatible in principle, but in practice they diverge. If science can discriminate between pictures of reality at all, it arrives at a strictly materialist conception, and adding God to that picture would only make it more complicated, so the hypothesis should be rejected by ordinary scientific standards. He presented the position as an old one, handed down from the Enlightenment, not a discovery of his own.²⁶²⁷²⁸ The word he set against theism in 2003 was materialism, not yet naturalism.²⁹ The timeline puts his declaration here.

In 2004, with the classicist Shadi Bartsch, he taught a Chicago course called Moments in Atheism, and found how little had been written about the history of unbelief, and how reluctant people had been to call themselves atheists before the nineteenth century.³⁰³¹ That June, on the blog he had begun, he defined the God he did not believe in: a conscious being with a part in creation, with supernatural powers, and able to care about human beings. If "God" meant only nature or love, he wrote, then fine, God exists, but why use the word.³²³³ That sentence is the test this book applies to everyone in it, and it is why he is here.

The blog years

For the next decade the blog carried his unbelief in short, dated pieces. When The God Delusion appeared in 2006 he had mixed feelings: he agreed with Dawkins that God does not exist, and thought that question relatively simple, but objected to mixing it up with two others, whether religion is harmful and why people are religious.³⁴ He quoted Terry Eagleton's jibe that reading Dawkins on theology was like reading a man whose only knowledge of biology came from a book of British birds, and answered that theology which does not bear on whether God exists is beside the point.³⁵³⁴ In 2007 he offered readers a choice of two worlds, one of impersonal laws and one with a caring deity, and said he would choose without hesitation the material world he actually believed in.³⁶³⁷

In 2009 he began to say that this was not enough. Atheists, he wrote, should diversify beyond scepticism and mocking creationists and put forward a positive programme for living without the comforting untruths of religion; Dawkins and his allies had done the useful work of showing that it was acceptable to disbelieve and be proud of it.³⁸³⁹⁴⁰ The same year he argued that science and religion are incompatible, but only as a matter of fact about the world we live in, not of logic, and that a religious person could be a good scientist.⁴¹ In 2011 he took on a colleague's firm agnosticism about life after death: given what physics knows, he wrote, we know there is no afterlife in the way we know the Moon is not made of cheese.⁴² Describing a television panel that year, he listed himself plainly as the committed atheist.⁴³

The arguments brought their first cost in 2012, when an essay of his for a Blackwell companion, arguing that a God with free choices sits badly with the qualities of a good scientific theory, was reported in the press. The mail that followed called him a servant of Satan and promised to see him in hell. William Lane Craig's reply on his podcast was, Carroll noted, more temperate.⁴⁴⁴⁵ That August he wrote that atheists were mostly right on the metaphysics but needed to raise their game on epistemology and ethics, and in October he convened a workshop called Moving Naturalism Forward, with Dawkins, Daniel Dennett, Steven Weinberg, Jerry Coyne and others, to begin the constructive work.⁴⁶⁴⁷⁴⁸ Naturalism was now his word.

Templeton

The one cost he chose for himself came in May 2013, when he explained in Slate why he would not take money from the John Templeton Foundation or speak at its events. The foundation was not evil, he wrote, but whenever respectable scientists took its money they lent their respectability to the idea that science and religion are two paths to the same truth, and he did not believe they were. The shift from theism to atheism, he added, was arguably the most important progress in fundamental ontology in five hundred years.⁴⁹⁵⁰⁵¹ Eight years later he put it more simply: he just thought they were wrong.⁴⁹

That is the whole of the price, as far as the record shows: hate mail, and money declined. He was denied tenure at Chicago in 2006 and moved to Caltech, but he gives academic reasons for it, and no one has tied the decision to his atheism.⁵²

New Orleans

The debate with Craig, at the Greer-Heard Forum of the New Orleans Baptist Theological Seminary in February 2014, was the high point of the arguing years. A month earlier he had held a dialogue with the theist philosopher Hans Halvorson at Caltech, and they had largely agreed; he went to New Orleans, he wrote, not to win but to be understood.² Craig argued from the universe's beginning and its fine-tuning; Carroll replied that models of the universe without a cause can be built, Hartle and Hawking's among them, and that demanding more than a complete and consistent model was a relic of a pre-scientific way of thinking.⁵³

Nobody judged it. Craig waited for the transcript and then replied in three posts that May. Carroll's sentence that metaphysics must follow physics, he wrote, was an expression of epistemological naturalism, and metaphysics by its nature goes beyond physics; physics stops at the beginning of the universe, so it cannot rule out a cause beyond it. He also conceded that one of Carroll's three complaints about his argument was quite correct.⁵³⁵⁴⁵⁵ Eleven years later, in a video looking back, Craig said he had carried virtually every argument, that Carroll had corrected him on a point about quantum mechanics, and that scientists carry an aura of authority with audiences that philosophers do not.⁵⁶⁵⁷ Both sides claimed the argument, and this book does not score it.

The other side

Craig is the main believing voice in this story, and his reason is a serious one: that a method which stops at physics cannot see what lies beyond physics.⁵⁴ The astrophysicist Luke Barnes, a Christian, read Carroll's 2016 book and said on radio in 2017 that it made no assumption of naturalism but argued its way there; he disagreed with the conclusion, of course, but he granted the method.⁵⁸⁵⁹ Carroll has returned the courtesy. He does not treat someone as an enemy because they disagree with him, he said in 2016, and he has kept a born-again cosmologist as a friend.⁶⁰²³

From argument to construction

The turn in his story is not a change of conclusion but of what he wanted to do with it. In October 2014 the Freedom From Religion Foundation gave him its Emperor Has No Clothes award, and he used the speech to talk about death: physics gives strong reason, never proof, to think there is no afterlife, and life is a process, not a substance.⁶¹⁶² Writing it up the next January, he said he had no real interest in giving talks that bashed religion, and cared much more for the hard, constructive work of exploring what naturalism implies.⁶²⁶³ On the timeline, this is where his revision falls.

The Big Picture (2016) gave the programme a name, poetic naturalism: there is only one world, the natural world, and there are many useful ways of talking about it. Naturalists are atheists, he told an interviewer, but the label states what one does believe rather than what one rejects. He still called the evidence that God does not exist pretty incontrovertible, and he still held that it is not true that every effect has a cause. Our beliefs, he said, hang together in planets of mutual support; our confidence should never reach exactly nothing or exactly certainty; and the finiteness of life is what gives it value.^6460656667 He gave the Gifford Lectures at Glasgow that year.⁶⁸ On a Christian radio programme in 2017 he said he was happy to be called an atheist, but that it was not the first description he would choose, because it names what he does not believe.⁵⁸⁶⁹

Since 2018 his podcast has carried the same temper. He is after the big ideas, he told the humanist theologian Anthony Pinn in its fourth episode, and asked whether atheism or humanism could supply the community that churches had.⁷⁰ He is not personally religious, he said in 2019, but he finds the history of religious thought fascinating and important.⁷¹⁷² In 2021 he told an oral historian that hectoring people and calling them irrational does not work, that the useful thing is to be friendly, likeable and open-minded, and that thinking like a scientist still leads to the conclusion that God does not exist.⁷³ In 2022 he became Homewood Professor of Natural Philosophy at Johns Hopkins, a joint post in physics and philosophy, which is to say the job of building the naturalism he had once only argued for.⁷⁴ In 2024, interviewing a scholar of a multiracial megachurch, he compared it, with curiosity rather than scorn, to the small parish of his boyhood.⁷⁵¹³

Did his unbelief change shape?

The conclusion has not moved in the forty years since a song at a Catholic university gave a quiet drift its name. What changed is the work he wanted to do with it. For a decade he argued that God does not exist, on blogs, in journals and on a seminary stage, and paid for it in hate mail and in money he declined. Then he decided that the argument was won and uninteresting, and that the harder task was to say what a world without God is like and how to live in it. He has never called himself an agnostic, and he still prefers to be known by what he believes.

Steven Weinberg, who joined Carroll's workshop in 2012 and drew the same conclusion from cosmology a generation earlier, has his own chapter in this book.

Footnotes

1. Blog, "William Lane Craig Debate", 28 January 2014 (texts/blog-2014-01-william_lane_craig_debate.txt); Reasonable Faith site search for "Sean Carroll" (texts/craig-rf-search-results.txt): list of Craig's podcasts and posts on Carroll, with the debate's title, (title truncated there); "Sean M. Carroll", English Wikipedia, revision 1379415860 of 2026-10-09. Used as a map and for birth date, Gifford Lectures and the 2012 Caltech debate, rev. 1379415860 (full title); "William Lane Craig vs Sean Carroll, 'God and Cosmology'", 2014 Greer-Heard Forum, 21 February 2014; ReasonableFaithOrg upload of 2014-03-03, 0:01 to 0:04. ↩

2. Blog, "William Lane Craig Debate", 28 January 2014. ↩ ↩²

3. "William Lane Craig vs Sean Carroll,…", about 8:40 to 9:40. ↩ ↩²

4. William Lane Craig, opening speech, 21 Feb 2014. He rejects "God of the gaps" reasoning and says cosmology does not prove God.: "William Lane Craig vs Sean Carroll,…", about 8:40 to 9:30. ↩

5. "William Lane Craig vs Sean Carroll,…", about 31:00 to 33:00; CraigRF368. ↩ ↩²

6. CraigRF368 (quoting Carroll's opening speech); "William Lane Craig vs Sean Carroll,…", about 31:15. ↩

7. "Sean M. Carroll", rev. 1379415860. Reported at second hand; the original has not been seen. ↩

8. Interview of Sean Carroll by David Zierler, 4 January 2021, Niels Bohr Library and Archives, American Institute of Physics (oral history 45034), answer on parents and neighbourhood. ↩ ↩²

9. AIP, answers on parents. ↩

10. AIP, answer to "Was the church part of your upbringing". ↩ ↩² ↩³

11. "Unbelievable? Sean Carroll (naturalism) vs Luke Barnes (theism)", Premier Christian Radio, host Justin Brierley, about 5:34 to 6:30. ↩ ↩²

12. Blog, "Post-Christian America", 5 April 2009 (texts/blog-2009-04-post_christian_america.txt), 5 April 2009. ↩

13. Mindscape podcast, episode 290, "Hahrie Han on Making Multicultural Democracy Work", 23 September 2024 (texts/mindscape-2024_09_23_290.txt), 0:43. ↩ ↩²

14. AIP, same passage and the next answer. ↩

15. AIP, answer on experiences that sparked his stand. ↩ ↩²

16. AIP; "Unbelievable? Sean Carroll (naturalism) vs Luke Barnes (theism)", about 5:06. ↩

17. AIP, same answer. ↩ ↩²

18. AIP, answers on college. ↩

19. AIP, answers on college and on foundations of physics. ↩

20. AIP, answer to "no experiences early in life". ↩ ↩²

21. "Tarkus", English Wikipedia, revision 1378565158 of 2026-10-05 (release date of the album that carries "The Only Way (Hymn)"), rev. 1378565158. ↩

22. "About", preposterousuniverse.com (career summary, Pennsbury High School); "Sean M. Carroll". Not verified. ↩ ↩²

23. AIP, answer on religion and departments. ↩ ↩²

24. AIP, answer on becoming a public intellectual. ↩

25. Sean M. Carroll, "Why (Almost All) Cosmologists are Atheists", prepared for the Notre Dame conference God and Physical Cosmology, January/February 2003; Faith and Philosophy 22 (2005), 622, header. ↩

26. Carroll, "Why (Almost All) Cosmologists are Atheists", abstract, introduction and conclusions. ↩

27. Carroll, "Why (Almost All) Cosmologists are Atheists", Conclusions (Faith and Philosophy 22, 2005). ↩

28. Carroll, "Why (Almost All) Cosmologists are Atheists", Introduction. ↩

29. Carroll, "Why (Almost All) Cosmologists are Atheists". ↩

30. Blog, "Moments in Atheism", March 2004; AIP. ↩

31. Blog, "Moments in Atheism", blog, March 2004. ↩

32. Blog, "God: threat, or menace?", June 2004 (texts/blog-2004-06-god_threat_or_menace.txt). ↩

33. Blog, "God: threat, or menace?", blog, June 2004. ↩

34. Blog, "The God Conundrum", 29 October 2006 (texts/blog-2006-10-the_god_conundrum.txt). ↩ ↩²

35. Terry Eagleton, literary critic, reviewing Dawkins in the London Review of Books (2006); quoted by Carroll. Aimed at Dawkins, not Carroll. Effect on Carroll: he agrees with Dawkins's conclusion but says theology that does not bear on whether God exists is "beside the point", and he faults Dawkins's strategy of mixing questions. Secondhand: the review itself was not fetched.: Blog, "The God Conundrum", blog, 29 Oct 2006. ↩

36. Blog, "Consolations of Materialist Philosophy", 11 July 2007 (texts/blog-2007-07-consolations_of_materialist_ph.txt). ↩

37. Blog, "Consolations of Materialist Philosophy", blog, 11 July 2007. ↩

38. Blog, "The Sacred", 26 January 2009 (texts/blog-2009-01-the_sacred.txt). ↩

39. Blog, "Post-Christian America". ↩

40. Blog, "Post-Christian America", blog, 5 April 2009. ↩

41. Blog, "Science and Religion are Not Compatible", 23 June 2009 (texts/blog-2009-06-science_and_religion_are_not_c.txt). ↩

42. Blog (cross-posted at Scientific American), "Physics and the Immortality of the Soul", 23 May 2011 (texts/blog-2011-05-physics_and_the_immortality_of.txt). ↩

43. Blog, "God and Cosmology Conversation", 9 August 2011 (texts/blog-2011-08-god_and_cosmology_conversation.txt). ↩

44. Sean Carroll, "Does the Universe Need God?", The Blackwell Companion to Science and Christianity, ed. James B. Stump and Alan G. Padgett (2012), section on personhood. ↩

45. Blog, "Let the Universe Be the Universe", 25 September 2012 (texts/blog-2012-09-let_the_universe_be_the_universe.txt); also reproduced in full in Craig's Q&A #286, 25 September 2012; Craig, Q&A #286 "Sean Carroll's Reply to the RF Podcast", 8 October 2012 (texts/craig-rf-carrolls-reply.txt). Reproduces Carroll's "Let the Universe Be the Universe". ↩

46. Blog, "Chatting Atheism", 19 August 2012 (texts/blog-2012-08-chatting_atheism.txt). ↩

47. Blog, "Moving Naturalism Forward: Videos and Recap", 11 December 2012 (texts/blog-2012-12-moving_naturalism_forward_vide.txt), 11 December 2012. ↩

48. Blog, "Chatting Atheism", blog, 19 Aug 2012. ↩

49. Sean Carroll, "Science and Religion Can't Be Reconciled: Why I won't take money from the Templeton Foundation", Slate, 9 May 2013 (first posted on his blog as "On Templeton", 8 May 2013), Slate; AIP. ↩ ↩²

50. Carroll, "Science and Religion Can't Be Reconciled:…", Slate, 9 May 2013. ↩

51. Carroll, "Science and Religion Can't Be Reconciled:…", Slate, 9 May 2013. ↩

52. AIP; "Sean M. Carroll". ↩

53. CraigRF368; CraigRF369; CraigRF370. ↩

54. William Lane Craig, Christian philosopher and apologist, the debate's opponent. His reason: physics stops at the origin of the universe, so a cause beyond it cannot be ruled out by physics. Effect on Carroll: none visible in his writing except to sharpen the point that "the question you should be asking is what is the best model"; Carroll's 2012 reply calls engaging Craig "fundamentally less interesting" than engaging open-minded people.: CraigRF368, 5 May 2014. ↩ ↩²

55. William Lane Craig, on Carroll's sentence "Our metaphysics must follow our physics" (see Q20).: CraigRF368, 5 May 2014. ↩

56. William Lane Craig (drcraigvideos), "What I Got Right (And Wrong) In My Debate with Sean Carroll", YouTube 9xOA2yJ-v7c, uploaded 2025-08-08; auto-captions (texts/craig-what-i-got-right.txt). ↩

57. William Lane Craig, 2025 video. Same video: Carroll "corrected me on that point" about quantum unitarity, and "the great high priests of our culture today are in fact professional scientists", a complaint about scientific authority. Fair reading: a combative self-assessment that also concedes an error.: (drcraigvideos), "What I Got Right (And Wrong)…". ↩

58. "Unbelievable? Sean Carroll (naturalism) vs Luke Barnes (theism)", about 5:34 to 6:30, 11:00 to 16:30, 18:17. ↩ ↩²

59. Luke Barnes, Christian astrophysicist, Sydney, co-author with the atheist Geraint Lewis of A Fortunate Universe; on Carroll's The Big Picture: "I disagree with the conclusion of course" but Carroll "argues to" naturalism. A believer reading Carroll fairly. Effect on Carroll: he repeats that naturalism is a conclusion, not an assumption.: "Unbelievable? Sean Carroll (naturalism) vs Luke Barnes (theism)", about 16:00. ↩

60. Émile P. Torres, interview with Sean Carroll, "'The evidence is pretty incontrovertible that he doesn't exist'", Salon, 8 May 2016 (by email; Carroll's answers are his own words). ↩ ↩²

61. Blog, "Life Is the Flame of a Candle", 3 January 2015 (texts/blog-2015-01-life_is_the_flame_of_a_candle.txt); "About"; "Sean M. Carroll". ↩

62. Blog, "Life Is the Flame of a Candle", 3 January 2015. ↩ ↩²

63. Blog, "Life Is the Flame of a Candle", blog, 3 Jan 2015. ↩

64. Salon. ↩

65. Salon. ↩

66. Salon, interview, 8 May 2016. ↩

67. Salon, interview, 8 May 2016. ↩

68. "Sean M. Carroll", rev. 1379415860. ↩

69. "Unbelievable? Sean Carroll (naturalism) vs Luke Barnes (theism)", about 5:45. ↩

70. Mindscape podcast, episode 4, "Anthony Pinn on Humanism, Theology, and the Black Community", 12 July 2018 (texts/mindscape-2018_07_12_episode_4.txt). ↩

71. Mindscape podcast, episode 48, "Marq de Villiers on Hell and Damnation", 27 May 2019 (texts/mindscape-2019_05_27_episode_48.txt). ↩

72. podcast, "Marq de Villiers on Hell and Damnation", Mindscape 48, 27 May 2019, about 2:00. ↩

73. AIP, answers on public image and religion. ↩

74. "About". ↩

75. podcast, "Hahrie Han on Making Multicultural Democracy Work". ↩