Author’s note: Theoretical physicist Sean Carroll was recently interviewed by podcaster Alex O’Connor and asked to defend his stance that one of the most thought-provoking scientific arguments for God’s existence, the argument from cosmological fine-tuning, “is the best argument for God, but it’s still a terrible argument.” I am responding to Carroll and other critics of the fine-tuning argument in a series of posts.
Find the full series so far here.
In my last post, I introduced the nature of the fine-tuning evidence and how it is structured, then outlined the multiverse as Carroll’s preferred explanation for it, mentioning some problems with multiverse cosmology that Carroll ignored. In this post, I’ll outline Carroll’s complaint that the fine-tuning argument for theism ignores counter-evidence that undermines it, then introduce responses that will be developed in greater detail later in this series.
Let me finish outlining my response to the cultured despisers of the fine-tuning argument (FTA), for whom Sean Carroll is functioning as the poster boy. My present concern is to articulate and confront his charge that the FTA engages in some evidential shenanigans, first by neglecting what he takes to be relevant disconfirming evidence for theism — including the non-centrality of humanity in the cosmos and the problem of divine hiddenness — then by indulging in post hoc fabrications in which, metaphorically speaking, a bullseye is painted around an arrow after it’s already lodged in something. All of this will feed into an overview of a cumulative evidential case from cosmological fine-tuning for theism, which will summarize the seventh and final stage of this series.
Stage 5: The Neglected Evidence Gambit
Carroll objects that the vast scale of our universe and our lack of centrality in it are (supposedly) unexpected on a theistic basis. In his accounting, this pulls in the opposite direction from the fine-tuning evidence and undermines it. Really? No. In fact, the center of the universe was not a place of honor in the medieval Aristotelian cosmos; it was the lowest point in the cosmic hierarchy. The move toward the center was toward change, corruption, and decay. In Dante, Hell and Satan himself are at the exact center. If anything, the Copernican displacement of Earth from the cosmological center was a promotion rather than a demotion.
Furthermore, rather than predicting a small, human-centered, and manageable cosmos, the biblical text and the history of theology consistently emphasize divine plenitude, generosity, and excess. The monotheistic traditions repeatedly point to the glory and grandeur of God. Consider the Psalms, for example, Psalm 19 — “the heavens declare the glory of God” — and Psalm 8 —“when I think of the heavens… what is mankind, that you are mindful of them?” Theologians from the first century to the present have seen creation’s vastness as reflective of God’s infinite power, goodness, and perfection, a recurrent theme in hymnody and doxology throughout Christian history. The idea that the divine perfections overflow into created abundance and plenitude was commonplace in pre-modern theology (Lovejoy 1936). Far from being contrary to expectation, the unfathomable scale of our universe is consonant with, and even expected from, traditional theological conceptions.
The “apparent lack of human centrality” is ambiguous at best. If it means the universe as a whole doesn’t look designed for human habitation and convenience, this was never a theistic prediction. If it means humans are insignificant in the cosmic scheme, this is a non sequitur. It does not follow. Significance is not determined by relative size. Human smallness against cosmic enormity is a theme of Scripture, yet one of the very passages that speak of our seeming insignificance in the scale of creation (“what is mankind, that you are mindful of them?”) also affirms our dignity (“yet you have made us a little lower than the angels and crowned us with glory and honor”). Carroll’s objection rests on assumptions about what theism predicts that do not survive historical or theological scrutiny.
Stage 6: The Hidden God and Post Hoc Charges
Carroll argues that God, if he existed, could “trivially easily” reveal himself, so his hiddenness counts against his existence and is counter to any fine-tuning evidence that might suggest the opposite. While there is indeed a dialogue regarding divine hiddenness that has a long history (Howard-Snyder and Moser, 2002), in trying to exploit divine hiddenness this way, Carroll assumes a view of God’s purposes that traditional theism rejects. Theists have long held that insofar as God is hidden, his hiddenness serves epistemic and moral goods, because both recognition of and love for God, and moral behavior, need to be uncoerced. A free human response is what God desires, not a constrained keeping of the moral speed limit because the cosmic cop is ever-present in our rear-view mirror. Granted, God is not a physical being; he transcends and grounds our sensory reality, so he is not present to our five physical senses. Granted, too, that God’s reasons for the specific hardships of our lives are often inscrutable. Nonetheless, it is possible for God to be approached, experienced, and known through reason and revelation by those who genuinely seek to do so. God’s existence is manifest to those who earnestly seek him with their whole being, and, unsurprisingly, not evident to those who do not wish to find him at all. So when Carroll treats divine hiddenness as an ad hoc excuse, he reveals his own priorities and ignores a deeply developed theological position with roots in Scripture and centuries of philosophical and theological reflection.
Carroll’s post hoc charge is also serious, but it too ultimately fails. In subsequent posts I will show that theism has generated predictions that were subsequently confirmed: the rational intelligibility of nature, its mathematical structure, and its amenability to scientific investigation were explicitly predicted by theistic natural philosophers and played a crucial role in the rise of modern science (Harrison, 2007, 2015; Gordon 2011b).1 As architects of the Scientific Revolution, Copernicus, Kepler, Galileo, Boyle, Newton, and many others expected rational order in nature because they believed that nature flowed from the rational mind of the Creator. That it should be lawful to the point of being mathematically describable was actively anticipated in medieval scholastic natural philosophy and made explicitly manifest by the key figures of the Scientific Revolution. For the evidence of the fine-tuning of the initial conditions, laws, and constants of nature to be taken as supportive of theism is thus not a post hoc retrofitting of theistic claims to modern scientific discoveries. It is a confirmation of prior expectations rooted in and predicted by the theistic worldview that gave birth to modern science.
Stage 7: The Cumulative Case
I have given an extensive overview of the posts to come. The final stage of this lengthy series will attempt to synthesize all of the arguments into a cumulative case for theism (see Swinburne, 2004 for a masterful extended version of just such a cumulative strategy). The evidence will combine in a framework demonstrating that:
- The FTA strongly confirms theism over naturalism (likelihood ratio >> 1)
- The multiverse alternative faces severe difficulties that compromise its explanatory power (and even if it were true, it would be better explained on a theistic basis)
- The “neglected evidence” that Carroll emphasizes does not significantly lower theism’s posterior probability
- The post hoc charge is historically mistaken — theism does generate genuine predictions that, in fact, catalyzed the Scientific Revolution.
With respect to the issue of “prior probabilities,” that is, how probable theism should be considered before assessing the fine-tuning evidence, I will argue that even small to modest priors2 yield high posteriors when the strength of the fine-tuning evidence is taken into account.
The conclusion of our evaluation will be that the fine-tuning of the universe for life provides substantial evidence for the existence of a transcendent intelligent cause. Carroll’s confident dismissal does not reflect the argument’s weakness but rather the strength of his naturalistic inclinations and his failure to engage the FTA in its strongest form. The argument he slanders as “terrible” turns out to be remarkably defensible and convincing.
On Method and Motivation
Throughout this series, I will do my best to take the FTA critics seriously. It is not my purpose to contend that all possible questions have already been settled in theism’s favor, but to show that on balance, carefully weighing all considerations, the evidence supports a design inference to theism far more strongly than it supports an indifferent naturalism. Carroll’s dismissive attitude toward the FTA tells us more about him than about the universe.
It’s clear that this topic is not just one of academic interest. Whether the universe shows evidence of purposive design has bearing on the deepest questions we can ask: Why is there something rather than nothing? Does existence have meaning? Are we alone in the cosmos? Whether or not Carroll dismisses such questions as matters for idle metaphysical speculation, most human beings — including most scientists throughout history — have thought them central to our self-understanding. The success of the fine-tuning argument would tell us something profound about the nature of reality that is very much worth getting right.
Next up: “The Bayesian Framework for the Fine-Tuning Argument.”
Notes
- I focus specifically on these points in an essay I co-authored with Stephen Meyer, “There and Back Again: How Theism Grounds Science and Science Abductively Supports Theism,” forthcoming in The Blackwell Companion to Christian Apologetics, edited by Timothy McGrew and Robert B. Stewart. Oxford: Wiley-Blackwell, 2026.
- Though I would contend that formidable philosophical arguments and considerations support the view that the priors in favor of theism are quite strong, so such modesty is unwarranted.