September 9, 2026Roque E. de Campos / Edit

This post could be written using the same logic, based on Saint Augustine, Saint Thomas Aquinas, and the Apostle Paul.

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, costly, capable of logical correction—but lazy, and frequently overcome 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 what the right answer is, and yet we cannot make that answer prevail.

Kahneman was an Israeli-American psychologist (who died in March 2024) who won the Nobel Prize in Economics in 2002—a rarity, given that he was never an economist but rather a cognitive psychologist—precisely because he, together with his longtime partner Amos Tversky, demolished the central assumption of classical economics that human beings make decisions rationally.

This structure — two faculties, one fast and one slow, the fast one prevailing even when the slow one is right — is not a 20th-century discovery. It is described, with remarkable precision, by Saint Augustine and Saint Thomas Aquinas, in moral and theological context, thirteen and eighteen centuries earlier, respectively.

2. Augustine: The Divided Will

In Book VIII of the Confessions, in the moment preceding his conversion, Augustine describes two wills within himself, an old one and a new one, in conflict—and the realization 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 does not obey itself. He draws this directly from Paul, Romans 7: “For I do not do the good I want to do, but the evil I do not want to do—this I keep on doing.” It is the same observation that Kahneman would later formalize: knowing the right answer is not the same as acting on it. The failure is not one of information—it is one of execution.

3. Thomas Aquinas: the passion that “binds” reason

Aquinas takes this to an even more technical level. In the Summa Theologica (I-II, question 77), he literally asks “whether passion diminishes or takes away the knowledge of the one who sins”—and answers that a strong passion can bind the use of reason at the moment of the act ( ligare usum rationis ), even if universal and correct knowledge remains intact in the mind. You continue to “know,” in the abstract sense—but the passion of the moment prevents that knowledge from being applied to the concrete case before you. It is almost a technical description of what we now call the capture of judgment by System 1: the person does not lose the information, but loses access to it at the instant of the decision.

There is also the positive side of this same coin: prudentia and habitus . For Aquinas, virtue is not about overcoming passion through sheer willpower each time—it’s about training the disposition through repetition until the right action becomes quick, almost automatic. He calls this knowledge per connaturalitatem : a knowledge that is already under one’s skin, that no longer needs explicit deliberation. Kahneman and Gary Klein would describe this, in 2009, as reliable specialized intuition—System 1 trained by extensive practice with clear feedback, and no more vice to correct. It is the same distinction that Gilbert Ryle, in the 20th century, would call “knowing how” versus “knowing that”: knowledge of the body and practice versus knowledge of proposition and axiom. Neither arises from pure syllogism—and that is why Einstein, speaking of Galileo, could say that “propositions reached by purely logical means are completely empty with respect to reality.” This applies to both physics and virtue.

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

Here we arrive at what is perhaps the most controversial, and the most interesting, point: Paul himself, in converting Jesus’ messages into the effective practice of Christianity, seems to have perceived—in pastoral experience, if not in explicit theory—exactly the same problem that Kahneman would formalize twenty centuries later.

Jesus’ teaching, as recorded in the Synoptic Gospels, is primarily 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 whoever hears has the capacity, by deciding, to walk towards 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 occurs when the human will, by itself, 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 doesn’t work—neither for zealous Jews (he himself, a scrupulous Pharisee, testifies to this in Romans 7), nor for Gentiles who would never assimilate the entire Torah. His answer is not “demand more, demand more”—it is to replace the entire regime. Galatians 5:17 is the most stark formulation of this: “For the flesh desires what is contrary to the Spirit, and the Spirit what is contrary to the flesh… so that you do not do what you want.” Deliberate will exists, knows what it wants, and yet it loses to a faster, automatic force—System 1 versus System 2, in Pauline vocabulary. And the solution he proposes next is not “strive harder so that the will wins”—it is “walk in the Spirit, and you will not fulfill the lust of the flesh” (Gal 5:16): a mechanism external to willpower, because he had already concluded, in practice, that willpower alone loses this battle.

This is the structural shift that Paul introduces into Christian practice: from an ethics of demand (you must) to an ethics of empowerment (you will receive the power to) — grace, faith, the Spirit dwelling in the person, instead of Law plus effort. There is a serious, and legitimate, debate about whether Paul was aware of this as a universal psychological theory or whether he arrived at it through concrete pastoral pressure — Krister Stendahl, in a classic 1963 essay, argues that the “introspective” reading of Romans 7 is, in large part, Augustine’s later projection onto the text, not Paul’s original intention, whose concern there would be more about the relationship between Jews and Gentiles before the Law than about universal moral psychology. But the practical point survives this doubt: whatever the degree of explicit theory behind it, the doctrine that Paul effectively constructs — and which has become the practice of Christianity — is an exact functional answer to the problem that Kahneman would describe: ordering the will is not enough; it is necessary to design a mechanism that does not depend on it alone.

It is also worth noting the opposing historical critique, lest we oversimplify: thinkers like Wilhelm Wrede (1904) called Paul the “second founder” of Christianity, and Nietzsche accused him of exchanging Jesus’ practical ethics for a theology of guilt. These criticisms do not say that Paul accommodated doctrine to weakness of 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 same structural change. It is up to the reader to decide whether what Paul did was an honest diagnosis or a power play; what does not change is that the architecture of the solution—of demanding empowerment—is precisely the correct answer to the problem of the divided will, whatever the motivation may have been.

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

Before concluding, it’s worth making a distinction that the euphoria surrounding the convergence between ancient theology and cognitive science might cause us to lose sight of: cognitive dissonance (Festinger, 1957) and what Kahneman described about System 1 and System 2 are not in the same theoretical category, and treating them as equivalent is a category error. Kahneman describes a general cognitive architecture—how the mind processes information quickly and slowly—tested and replicated in dozens of independent domains: probability judgment, memory, perception, expertise. Cognitive dissonance is a narrower, and far more contested, theory about how the mind reduces the discomfort of holding conflicting beliefs; it originated from a specific case (the UFO cult of the “Seekers,” studied in “When Prophecy Fails,” 1956) and has since been stretched, by many, to serve as a universal explanation for any belief with which the observer already disagrees.

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

This doesn’t mean that cognitive dissonance never occurs, nor that theodicies are automatically correct simply because they escape accusation. It means that accusation, by itself, solves nothing: it describes, at best, a possible psychological mechanism, not a test of the thesis being discarded. 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 type 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. Gary’s case: diagnosis or distortion?

I’m going to take advantage of the friendship of a great friend of mine, Gary A. Stilwell, because he is one of the modern philosophers who best exemplifies what seems to me a mistake in not taking into account the arguments presented here and what Daniel Kahneman discovered.

Gary A. Stilwell’s seminal 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 of Christianity regarding the Problem of Evil—the incongruity between an omnipotent and benevolent God and the reality of suffering. The distinctive feature of his work is that it proposes that, in the face of the failure of conventional religious theodicies, modern science can offer a new platform and new answers for understanding this question.

His proposition will be discussed later as soon I have time to use the same reasoning here why it is not possible to science to replace religion

Gary, in addition to his argument about the problem of evil and cognitive dissonance, harbors a rejection of the apostle Paul that goes beyond intellectual disagreement and borders on personal contempt. The accusation, which he inherits from a lineage stretching from Nietzsche to Wrede, is that Paul did not develop Jesus’ teachings: he replaced them with something else—a theology of guilt and dependence, useful for controlling consciences, without any organic connection to what Jesus actually preached. And cognitive dissonance, in Gary’s vocabulary, is the comfortable mechanism that explains why Christians defend this substitution: they need to reduce the tension between a good God and a world of suffering, and Paul gave them the theological tool—grace, original sin, vicarious redemption—to do so.

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

Criterion	Saint Augustine (354–430)	Saint Thomas Aquinas (1225–1274)	Paul the Apostle (c. 5–67 AD)
Philosophical Basis	Platonism (and Neoplatonism).	Aristotelianism.	No formal Greek philosophical system. Pharisaic-rabbinic Judaism of the Second Temple, with tangential contact with Stoic categories and Hellenistic rhetoric (cf. Acts 17), but a decidedly non-philosophical basis: the apocalyptic revelation of the resurrected Christ.
Faith and Reason	Faith comes first. You need to “believe in order to understand.” Reason helps to clarify what you already believe.	Faith and reason are distinct, yet 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, it argues with dialectical rigor within the framework of faith (Romans is, formally, a treatise). A direct precedent of Augustine’s “believing in order to understand.”
Theory of Knowledge	Theory of Divine Illumination: the human mind needs God’s light to attain eternal truths.	Aristotelian empiricism: knowledge begins with the senses and experience of the physical world.	No formal epistemology. Anthropological category: spiritual knowledge comes from the action of the Spirit upon the nous against the sarx — “the eyes of the heart enlightened” (Ephesians 1:18). Closer to Augustine’s model of illumination, but pneumatological, not philosophical.
Philosophical School	Patristics (Philosophy of the Church Fathers).	Scholasticism (Philosophy of medieval universities).	Neither — precedes both. Apostolic source from which Patristics and Scholasticism draw and systematize categories.

What this chart shows is not that Paul would “agree” with Augustine or Aquinas on philosophy—he had no systematic philosophy whatsoever, as the chart itself makes clear. It shows that the two thinkers who most shaped Western Christian theology, working within mutually incompatible philosophical traditions (Augustinian Platonism versus Thomistic Aristotelianism), each starting from scratch in their own system, arrived precisely at the diagnosis that was already operating, in pastoral practice, in Paul’s letters: a divided will, reason that knows but does not conquer, the need for a mechanism that does not depend solely on deliberate effort. And a third observer—Kahneman, without any theological commitment, working with experimental psychology and behavioral economics four centuries after Aquinas and nineteen after Paul—rediscovers the same structure through a fourth, entirely different path.

This is the opposite of what Nietzsche and Wrede’s thesis predicts. If Paul had simply invented universal guilt to fabricate dependence on grace—a power play, not an honest diagnosis—it would be a remarkable coincidence that two theologian-philosophers from incompatible systems and a secular cognitive scientist, with no common incentive to validate Paul’s move, had independently reconstructed the same structure of the problem he claimed to be solving. Arbitrary inventions are not usually convergently rediscovered by observers who have no reason to agree with each other.

I need to apply the same discipline from the previous section here: this establishes that Paul was an accurate diagnostician of the human condition, and that his solution has the correct structural form—it does not establish that grace, the Holy Spirit, or redemption are metaphysically real. A completely secular reader can accept all this and remain an atheist; the convergence validates Paul’s psychology, not his theology. This distinction is what prevents the argument from becoming cheap apologetics.

But it also throws the problem back into Gary’s lap. If the convergence between Augustine, Aquinas, and Kahneman doesn’t prove Paul’s metaphysics, it also doesn’t leave room to dismiss him as a mere blame-maker—his diagnosis was verified in three independent ways, by people who had no reason whatsoever to agree with each other. It remains to be asked why cognitive dissonance, a tool Gary wields with such confidence to disarm Paul, is never applied by him to his own side: why the possibility that his rejection of Paul is driven by a need to reduce the tension between “evil is proof against God” and “this specific apostle built a solid obstacle to this thesis” simply doesn’t enter the equation. It’s the same old asymmetry—the weapon only fires in one direction—and that’s exactly what Kahneman, unintentionally, 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’s bias. Gary included. Me included.

7. What remains in the end: the path, not the verdict.

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

It’s the same inversion that Kierkegaard recorded in 1843, albeit in a completely different way: “life can only be understood backwards, but it must be lived forwards.” And it’s the same thing that Augustine, Thomas Aquinas, and Paul understood about the will: what matters is not the logical axiom that would solve the problem at once—it’s what lies beneath the skin, formed slowly, little by little.