1. Two speeds, one conflict

Daniel Kahneman described the human mind as governed by two systems: System 1, fast, automatic, associative, driven by immediate impression; and System 2, slow, deliberate, effortful, capable of logical correction — but lazy, and frequently overruled by what System 1 has already decided first. The central finding is not that we are irrational by accident; it is that we often know which answer is correct, and still cannot make that answer win.

This structure — two faculties, one fast and one slow, the fast one winning even when the slow one is right — is not a twentieth-century discovery. It is described, with remarkable precision, by Saint Augustine and by Saint Thomas Aquinas, in moral and theological terms, thirteen and eighteen centuries earlier.

2. Augustine: the divided will

In Book VIII of the Confessions, at the moment preceding his conversion, Augustine describes two wills within himself, one old and one new, in conflict — and the observation that the mind “commands itself and is not obeyed”: imperat animus ut velit animus… et non facit — the mind commands the mind to will, and is not obeyed. He draws this directly from Paul, Romans 7: “For what I do is not the good I want to do; no, the evil I do not want to do—this I keep on doing.” It is the same observation Kahneman would later formalize: knowing the right answer is not the same thing as acting on it. The failure is not one of information — it is one of execution.

3. Aquinas: the passion that “binds” reason

Aquinas takes this to an even more technical register. In the Summa Theologiae (I-II, question 77), he literally asks “whether passion diminishes or removes the sinner’s knowledge” — and answers that a strong passion can bind the use of reason at the moment of the act (ligare usum rationis), even though universal, correct knowledge remains intact in the mind. You go on “knowing,” in the abstract sense — but the passion of the moment prevents that knowledge from being applied to the concrete case in front of you. It is almost a technical description of what we today call the capture of judgment by System 1: the person does not lose the information, they lose access to it at the instant of decision.

There is also the positive side of the same coin: prudentia and habitus. For Aquinas, virtue is not winning against passion by sheer willpower every single time — it is training the disposition through repetition until the right action becomes fast, almost automatic. He calls this knowledge per connaturalitatem: a knowing that is already under the skin, that no longer needs explicit deliberation. Kahneman and Gary Klein would describe this, in 2009, as reliable expert intuition — System 1 trained by extensive practice with clear feedback, no longer a bias to correct. It is the same distinction Gilbert Ryle, in the twentieth century, would name “knowing how” versus “knowing that”: knowledge of the body and of practice against knowledge of proposition and axiom. Neither one is born of pure syllogism — which is why Einstein, speaking of Galileo, could say that “propositions arrived at by purely logical means are completely empty as regards reality.” That holds as much for physics as it does for virtue.

4. Paul: the apostle who already knew this in practice

Here we arrive at what may be the most controversial, and the most interesting, point: Paul himself, in converting Jesus’s message into the actual practice of Christianity, appears to have grasped — in pastoral experience, if not in explicit theory — exactly the same problem Kahneman would formalize twenty centuries later.

Jesus’s teaching, as recorded in the Synoptic Gospels, is mostly a direct moral demand: “You have heard that it was said to the people long ago… but I tell you” (Matthew 5) — a call to radical conversion (metanoia), presupposing that the listener has the capacity to decide and walk toward the ideal. It is a demand: love your enemies, turn the other cheek, sell what you have. There is no explicit theological mechanism in the Synoptics for how this transformation happens when the human will, on its own, fails.

Paul, writing decades later to Gentile communities, without having known Jesus in life, faces a concrete practical problem: demanding compliance with the Law simply does not work — not for zealous Jews (he himself, a scrupulous Pharisee, testifies to this in Romans 7), nor for Gentiles who would never assimilate the whole Torah. His answer is not “demand more, push harder” — it is to replace the entire regime. Galatians 5:17 is the barest statement of this: “For the flesh desires what is contrary to the Spirit, and the Spirit what is contrary to the flesh… so that you are not to do whatever you want.” Deliberate will exists, knows what it wants, and still loses to a faster, automatic force — System 1 against System 2, in Pauline vocabulary. And the solution he proposes next is not “try harder so the will wins” — it is “walk by the Spirit, and you will not gratify the desires of the flesh” (Gal 5:16): a mechanism external to willpower, because he had already concluded, in practice, that willpower alone loses that fight.

This is the structural turn Paul introduces into Christian practice: from an ethic of demand (you must) to an ethic of enablement (you will be empowered to) — grace, faith, the Spirit indwelling the person, in place of Law plus effort. There is a serious, legitimate debate over whether Paul was conscious of this as a universal psychological theory or arrived there through concrete pastoral pressure — Krister Stendahl, in a classic 1963 essay, argues that the “introspective” reading of Romans 7 is largely a later projection of Augustine onto the text, not Paul’s original intent, whose concern there was more about the relationship between Jews and Gentiles before the Law than about universal moral psychology. But the practical point survives that doubt: whatever the degree of explicit theory behind it, the doctrine Paul actually builds — and which became the practice of Christianity — is a functionally exact answer to the problem Kahneman would describe: commanding the will is not enough; you have to design a mechanism that does not depend on the will alone.

It is worth registering the opposite historical critique too, so as not to oversimplify: thinkers such as Wilhelm Wrede (1904) called Paul the “second founder” of Christianity, and Nietzsche accused him of trading Jesus’s practical ethic for a theology of guilt. These critiques do not say Paul accommodated doctrine to the weakness of the will out of pastoral compassion — for Nietzsche, on the contrary, Paul invented the category of universal sin to generate dependence on grace, which is a cynical reading of the very same structural shift. It is left to the reader to decide whether what Paul did was honest diagnosis or a power play; what does not change is that the architecture of the solution — from demand to enablement — is exactly the correct answer to the problem of the divided will, whatever the motivation behind it.

5. A category error: cognitive dissonance is not what Kahneman discovered

A distinction is worth making that the excitement of convergence between ancient theology and cognitive science can obscure: cognitive dissonance (Festinger, 1957) and what Kahneman described about System 1 and System 2 are not in the same category of theory, and treating them as equivalent is a category error. Kahneman describes a general cognitive architecture — how the mind processes information fast and slow — tested and replicated across dozens of independent domains: probability judgment, memory, perception, expertise. Cognitive dissonance is a narrower, and considerably more contested, theory about how the mind reduces the discomfort of holding conflicting beliefs; it was born from a specific case (the “Seekers” UFO cult, studied in When Prophecy Fails, 1956) and has since been stretched, by many people, into a universal explanation for any belief the observer already disagrees with.

This is exactly where the problem lies when someone uses cognitive dissonance to attack, for instance, the problem of evil. Using “that’s cognitive dissonance” to explain why someone holds to privatio boni, felix culpa, or any theodicy is committing the genetic fallacy: confusing the psychological origin of a belief with its truth value. Even if it were one hundred percent true that someone builds these ideas because they need to reduce the tension between “I have terminal cancer” and “the world makes sense,” that says nothing about whether privatio boni is correct as a metaphysical thesis. The genesis of an idea in the mind of whoever holds it is irrelevant to whether it is true — Kekulé dreamed of a snake biting its own tail and arrived at the structure of benzene; the dream’s origin does not invalidate the chemistry.

This does not mean cognitive dissonance never occurs, nor that theodicies are automatically correct for escaping the accusation. It means the accusation, by itself, settles nothing: at best it describes a possible psychological mechanism, not a test of the thesis being dismissed. Confusing the two — mechanism of origin with truth value — is the same category error committed when treating cognitive dissonance as if it were the same kind of finding as Kahneman’s System 1/System 2: one is a general model of cognitive architecture, with decades of replication; the other is a specific theory of limited scope, frequently used outside the domain in which it was originally tested.

6. The case of Gary: diagnosis or distortion?

I am going to impose on the friendship of a great friend of mine, Gary A. Stilwell, because he is one of the modern thinkers who best exemplifies what seems to me a mistake — not taking into account the arguments presented here, and what Daniel Kahneman discovered.

Gary A. Stilwell’s principal book on the contradiction between traditional theology and the existence of evil is titled Where Was God: Evil, Theodicy, and Modern Science. In this foundational work of his research, the author questions the traditional philosophical and theological justifications Christianity offers for the Problem of Evil — the incongruity between an omnipotent, good God and the reality of suffering. What sets his work apart is the proposal that, given the failure of conventional religious theodicies, modern science can offer a new platform and new answers for understanding the question.

Gary, beyond his argument about the problem of evil and cognitive dissonance, holds toward the apostle Paul a rejection that goes past intellectual disagreement and comes close to personal contempt. The charge, which he inherits from a lineage running from Nietzsche to Wrede, is that Paul did not develop Jesus’s teaching: he replaced it with something else — a theology of guilt and dependence, useful for controlling consciences, with no organic relationship to what Jesus actually preached. And cognitive dissonance, in Gary’s vocabulary, is the convenient mechanism that explains why Christians defend that replacement: they need to reduce the tension between a good God and a world with suffering, and Paul handed them the theological tool — grace, original sin, vicarious redemption — to do it.

I disagree, flatly. And the basis of that disagreement is not theological taste — it is the picture that emerges when Paul is placed alongside Augustine and Aquinas:

Criterion	Saint Augustine (354–430)	Saint Thomas Aquinas (1225–1274)	The Apostle Paul (c. 5–67 AD)
Philosophical basis	Platonism (and Neoplatonism).	Aristotelianism.	No formal Greek philosophical system. Second Temple Pharisaic-rabbinic Judaism, with tangential contact with Stoic categories and Hellenistic rhetoric (cf. Acts 17), but an avowedly non-philosophical foundation: the apocalyptic revelation of the risen Christ.
Faith and reason	Faith comes first. One must “believe in order to understand.” Reason helps clarify what is already believed.	Faith and reason are distinct but complementary. Both come from God and cannot contradict each other.	Faith is a response to the kerygma, not the conclusion of a philosophical argument — “the message of the cross is foolishness to those who are perishing” (1 Corinthians 1:18). Even so, he argues with dialectical rigor from within faith (Romans is, formally, a treatise). A direct precedent for Augustine’s “believe in order to understand.”
Theory of knowledge	Theory of Divine Illumination: the human mind needs God’s light to reach eternal truths.	Aristotelian empiricism: knowledge begins in the senses and in experience of the physical world.	No formal epistemology. An anthropological category: spiritual knowledge comes from the Spirit acting on the nous against the sarx — “the eyes of your heart enlightened” (Ephesians 1:18). Closer to Augustine’s illumination model, but pneumatological, not philosophical.
Philosophical school	Patristics (the philosophy of the Church Fathers).	Scholasticism (the philosophy of the medieval universities).	None — precedes both. The apostolic source from which Patristics and Scholasticism draw and systematize categories.

What this table shows is not that Paul would “agree” with Augustine or Aquinas on philosophy — he had no systematic philosophy at all, as the table itself makes plain. What it shows is that the two thinkers who most shaped Western Christian theology, working in mutually incompatible philosophical traditions (Augustinian Platonism against Thomist Aristotelianism), each starting from scratch within his own system, arrived at exactly the diagnosis that was already operating, in pastoral practice, in Paul’s letters: a divided will, reason that knows and does not win, the need for a mechanism that does not depend on deliberate effort alone. And a third observer — Kahneman, with no theological commitment whatsoever, working in experimental psychology and behavioral economics four centuries after Aquinas and nineteen after Paul — rediscovers the same structure by a fourth, entirely different route.

This is the opposite of what Nietzsche’s and Wrede’s thesis predicts. If Paul had simply invented universal guilt to manufacture dependence on grace — a power play, not an honest diagnosis — it would be a remarkable coincidence that two philosopher-theologians working in incompatible systems, and one secular cognitive scientist, with no shared incentive whatsoever to validate Paul’s move, would independently reconstruct the very same structure of the problem he claimed to be solving. Arbitrary inventions are not usually rediscovered convergently by observers who have no reason to agree with one another.

I need to apply here the same discipline as in the previous section: this establishes that Paul was a precise diagnostician of the human condition, and that his solution has the correct structural shape — it does not establish that grace, the Holy Spirit, or redemption are metaphysically real. An entirely secular reader can accept all of this and remain an atheist; the convergence validates Paul’s psychology, not his theology. That distinction is exactly what keeps the argument from turning into cheap apologetics.

But it also hands the problem back to Gary. If the convergence between Augustine, Aquinas, and Kahneman does not prove Paul’s metaphysics, it also leaves no room to dismiss him as a mere manufacturer of guilt — his diagnosis was verified in three independent ways, by people who had no reason at all to agree with each other. Which leaves the question of why cognitive dissonance, the tool Gary wields with such confidence to disarm Paul, is never turned on his own side: why the possibility that his rejection of Paul is driven by the need to reduce the tension between “evil is evidence against God” and “this particular apostle built a solid obstacle to that thesis” simply never enters the accounting. It is the same old asymmetry — the weapon only fires in one direction — and this is exactly what Kahneman, without meaning to, makes untenable: if the cognitive apparatus captures everyone equally, no one has the right to declare themselves the neutral observer who only sees the other side’s bias. Gary included. Myself included.

7. What remains at the end: a path, not a verdict

Kahneman also documented the difference between the “experiencing self” and the “remembering self” — the self of experience, which registers each moment as it happens, and the self of memory, which afterward reconstructs everything as a compressed story, dominated by the peak-end rule (we judge an entire experience by its most intense moment and by how it ended) and by duration neglect (how long something lasted barely counts in the final judgment). The mental apparatus fixes on where it ended up — not on the real sum of what was lived.

It is the same inversion Kierkegaard recorded, in 1843, by an entirely different route: “life can only be understood backwards, but it must be lived forwards.” And it is the same thing Augustine, Aquinas, and Paul perceived about the will: what matters is not the logical axiom that would settle the problem once and for all — it is what settles under the skin, formed slowly, step by step along the way.