The Puppet Strings of Psychology

Imagine a puppet show. The puppet dances, shakes, and bows very naturally, yet every movement is prescribed, and every gesture is caused by strings pulled off-stage. In much of modern psychology, the human being is cast in a similar way: a biological puppet manipulated by hidden strings of heredity, neural firings, and environmental conditioning. This is the doctrine of psychological determinism. Rooted in positivist assumptions and strengthened by behaviorism, neuroscience, and mechanistic models of mind, it holds that freedom is an illusion. But can a science that denies free will also offer a coherent understanding of responsibility, agency, or personhood?

The Thomistic tradition responds with a resounding no. From its philosophical foundations, it critiques the determinist error and proposes a vision of the human person as a rational agent capable of genuine freedom.

What Is Psychological Determinism?

Psychological determinism is the belief that all human behavior is causally determined by prior physical or psychological conditions. Early behaviorists like John B. Watson and B.F. Skinner took this idea to its extreme: every action, they argued, is just a link in a chain of stimulus and response. Skinner even declared free will a myth—merely a name for behaviors whose causes remain unknown.

Later models in cognitive neuroscience reinforced this outlook by interpreting brain activity as a complex but ultimately deterministic machine. Thoughts, choices, and even moral decisions are treated as outputs of neural algorithms.

Although some scientists present this approach as methodologically neutral—“we study behavior as if it were determined”—in practice it often morphs into philosophical determinism, the belief that free will does not, and cannot, exist.

Charting Psychology’s Course Toward Determinism

The road that led psychology to deny the existence of free will can be sketched through a familiar sequence—what some might call the usual suspects, often referenced in other articles on this blog. It begins with Cartesian dualism, which by separating mind and body, made the latter ripe for mechanistic interpretation. Kant’s epistemology further denied access to noumenal reality, leaving psychology with only phenomenal appearances. In reaction, empiricist and positivist psychologists like Mill, Watson, and Skinner sought to explain behavior without invoking immaterial faculties.

Behaviorism saw the mind as a “black box,” irrelevant to scientific psychology. Even cognitive science, while restoring some talk of mental representation, often preserves the deterministic framework: thoughts are just outputs of the brain-as-computer. This history has left a lasting mark. After all, without liberty, we are “a king without scepter and crown,” as Gruender memorably said; but also because, as Brennan observed, psychology’s rejection of the soul, the mind, and the will gradually caused it to lose sight of the person.

Why Is This Troubling?

As noted above, the deterministic turn in psychology is not a neutral development—it profoundly alters how we understand human beings, their actions, and their moral worth. While some defenders of determinism argue that it enhances scientific predictability, the common sense” and Thomistic tradition exposes its conceptual and existential costs.

The Collapse of Moral Responsibility

If every action is the inescapable effect of antecedent conditions—be they genetic, environmental, or neurological—then the notion of moral responsibility becomes incoherent. In a deterministic framework, a person does not choose to lie, to forgive, to resist temptation, or to help a stranger; they merely manifest what was already encoded in their causal matrix. This undermines not only legal responsibility but also the entire edifice of natural morality.

As Brennan rightly observes, “it is idle to speak of norms of right conduct or the justice of rewards and punishments, unless the human will has the power of choice”. Praise and blame become irrational if agents have no real power to do otherwise. Without freedom, virtue is no longer cultivated but biologically predetermined; sin is not a fault, but a misfiring; rehabilitation is pointless, and justice devolves into deterministic administration.

Consequences for Therapy and Education

A deterministic psychology risks turning therapy and education into mechanical engineering. If a person is merely a system of inputs and outputs, then therapy becomes conditioning and education becomes manipulation.

Take behaviorist teaching methods. They may succeed at rote memorization but fail to form character. A Thomistic pedagogy, by contrast, seeks to cultivate the rational soul: to form habits of virtue, foster understanding, and direct the will toward the good—as we will see later. In therapy, deterministic models may diminish hope. If addiction is purely biochemical, then the freedom to change seems illusory. But as Thomist thinkers like Donceel argue, true willpower lies not in the intensity of desire but in the constancy of choosing the good. The addict may have strong urges, but unless those urges are freely endorsed, they do not constitute acts of the will.

Based on the above, it becomes clear that at an existential level determinism fosters fatalism. If our future is prewritten in our neurons or environment, then why strive for excellence? Why cultivate virtue? Why bother trying to correct an impulse or urge that seems impossible to change? As William James remarked, determinism may function scientifically, but it fails utterly “in meeting human needs for purpose and accountability.”

Freedom as a Mark of Rational Nature

Determinists often argue that the only alternative to their view is indeterminism, or in other words, chaos, and randomness. But this is a false dichotomy. The true alternative is not blind chance, but freedom grounded in reason.

The Will as Rational Appetite

In contrast to deterministic models, Thomistic psychology understands the human will as a rational appetite for the good, guided by intellect. We do not act like billiard balls struck by external forces. We recognize possible goods and deliberately choose among them. The act of will, as Aquinas insists, is not fixed by external causality but directed by internal reasoning toward an end.

Meaning over Mechanism

Donceel and other Thomists argue that mental events are not just caused; they are motivated by meaning. In other words, mental acts are intentional: they are always “about” something. Anger, for example, is not merely a neurochemical event but a judgment-laden reaction to perceived injustice. Thomistic analysis insists that psychological states cannot be fully explained by physical causes because they carry meaning — a dimension absent in matter.

A shove in a crowd does not cause rage like vinegar causes rust. The shove is interpreted; it is the motive, not a mechanical cause. The act of getting angry is therefore not reducible to neural arousal, but an act of meaning made by a rational soul.

The Soul as Agent-Cause

In every truly human act, the final explanation lies not in antecedent conditions but in the agent—the person. It is therefore no surprise that Donceel identified three fundamental sources of behavior: heredity, environment, and the person’s free will. Only the will —a faculty of the spiritual soul— allows for self-determination. The person is not merely shaped by causes but also forms themselves through choice. This is the essence of moral development, something deterministic models cannot account for.

The Choice Before Psychology

Determinism, though cloaked in scientific language, impoverishes psychology. It makes people predictable but not intelligible, programmable but not responsible. Thomistic psychology, by contrast, reclaims the central truth of human freedom: that we are not marionettes, but monarchs. We do not merely respond to causes; we choose among goods, direct our lives, and shape our character.

As science continues its advance, it must be guided by a sound philosophy. Aquinas reminds us that freedom is not a luxury —it is the crown of rational nature. A psychology that rediscovers this truth will not only explain more, but heal more— for it will treat the human not as a machine, but as someone capable of truth, love, and real choices.

Nicolás Eyzaguirre Bäuerle

Editor-in-chief

Next
Next

When Mind and Body Divorce