The Forgotten “Why"

Modern psychology has achieved remarkable empirical advances, mapping neural circuits, decoding behaviors, and developing therapies grounded in cognitive and behavioral science. Yet, as many reflective scholars have noted, something essential seems missing: purpose. Why do human beings act, desire, or strive? Contemporary psychology typically explains behaviors in terms of past causes (stimuli, conditioning, evolution) or mechanistic processes, but rarely asks about the end or telos toward which these acts are directed.

This article will explore how teleology — purpose or final causality — came to be excluded from mainstream psychology, why that exclusion impoverishes our understanding of the human person, and how a return to Aristotelian-Thomistic final causality could enrich and unify psychological science.

But first, to understand what has been lost, we must unpack the classical doctrine of the four causes, as well as the richness behind a concept with which we are unfamiliar.

Rediscovering an Ancient Framework

The Four Causes

At the heart of this critique lies the classical doctrine of the four causes, drawn from Aristotle and developed by St. Thomas Aquinas. These causes are the material, formal, efficient, and final causes, each offering a distinct yet interrelated dimension of explanation. According to Arnold and Gasson, the material cause refers to the matter from which something is made: for example, the marble in a statue or, analogously, the biological substrate of the human body. The formal cause is the organizing principle or essence that makes a thing what it is; in human beings, this is the soul, the substantial form that organizes the body. The efficient cause concerns the agent or process that brings something into being — the sculptor shaping the marble, or the parents begetting a child. But most crucially, the final cause is the end, the purpose, the “for the sake of which" something exists or acts. As Cardinal Mercier notes: “The final cause is not merely an add-on but a constitutive aspect of explanation." Without it, we are left with a hollow chain of events lacking direction and meaning.

Telo... what?

Understanding What Is Teleology And Its Relation With Human Nature

Teleology is derived from the Greek telos (end or goal). As mentioned before, In Aristotle’s framework the final cause is the “that for the sake of which” a thing exists or an action is done — in other words, its purpose. St. Thomas Aquinas built on this idea, affirming that every agent acts for an end and that all human actions are oriented toward some good, whether in itself or perceived as such.

Unlike inanimate nature — which has unconscious tendencies toward ends —, human beings are rational agents who deliberately pursue goals. Aquinas describes the human will as a “rational tendency or inclination to the good.” By our very nature, we seek what appears good for us; every choice aims at some end conceived as fulfilling. Ultimately, the Aristotelian-Thomistic view holds, that there must be an ultimate end — an “end of ends” — that gives meaning and direction to all the intermediate goals we seek. Aquinas identifies this ultimate end as beatitudo or perfect happiness, which is found in union with God.

Importantly, acknowledging final causes does not mean ignoring efficient causes. Rather, it situates them in a broader context. For Aristotle and Aquinas, the final cause is “first in intention and last in execution.” For example, the purpose of acorns is to grow into oak trees — that final cause guides the biological processes (efficient causes) of growth. In human action, the purpose or goal we intend comes first in our mind and guides the sequence of steps we take to achieve it. Every human act, Aquinas argues, can only be fully explained by identifying the end it is meant to achieve.

Thus, teleology provides the organizing principle for understanding behavior: just as an archer’s shot is explained by the target he aims for, so a person’s actions are explained by the goal or good he seeks. The Aristotelian-Thomist tradition conceptualizes the human person as an integrated whole — a body-soul composite — whose faculties — like intellect and will — are ordered toward truth and goodness as their proper ends. In this view, rationality itself is teleological: the intellect naturally aims at knowing reality (truth) and the will naturally aims at loving and choosing what is truly good. Teleology, then, is not an extraneous add-on for psychology, but a fundamental aspect of human nature.

Forgetting Teleology

Historical Roots of Teleological Oblivion

If teleology is so integral to understanding human nature, how did it come to be purged from modern psychology? The answer lies in an intellectual shift that began with René Descartes’ 17th-century dualism, which conceived human beings as mind and matter, but not in the classical sense upheld by Aristotle and Saint Thomas, where the person is a body informed by the soul. For this French thinker, the soul and the body are two distinct realities, connected by the pineal gland. Descartes’ influence led thinkers to prioritize mechanistic and mathematical explanations, discarding Aristotle’s focus on final causes. Enlightenment empiricists like Hume and the British associationists further reduced the mind to a collection of linked sensations, ignoring any inherent directedness. By the 19th century, positivists like Auguste Comte declared science should focus only on how things happen, not why, pushing psychologists to model their field on the physical sciences. In short, the early moderns shifted the focus to efficient causes (physical processes, stimuli, past events) and away from final causes.

In the late 19th and early 20th centuries, experimental psychologists like Wilhelm Wundt focused on analyzing conscious experience without reference to purpose, and behaviorists like John B. Watson and B.F. Skinner dismissed inner goals or desires as unscientific, reducing behavior to stimulus-response patterns. Even Freud, though attentive to motives, framed them as instinctual drives, not rational pursuits of the good. While American functionalists like William James saw purposes pragmatically, not as intrinsic ends. By mid-century, psychology had splintered into competing schools, none offering a unified account of human purpose.

Why Is This Troubling?

Fragmented Theories of the Person

Without a unifying teleological vision, psychology splinters into competing approaches that each capture only a part of human reality. One school focuses exclusively on lower-order processes (e.g., reflexes or neural circuits), another on isolated aspects of mind (like memory or emotion in a vacuum), another on social conditioning, etc. These approaches often talk past each other because there is no agreement on what the human being is for. By contrast, a teleological lens would insist that all these aspects are integrated in a rational creature oriented to some ultimate good. Without that lens, integration falters.

Reductionism — Man as “Nothing But”

Hand in hand with fragmentation comes reductionism. Each school tended to reduce the human being to the level explicable by its preferred causes. The behaviorist said: man is nothing but a conditioned animal responding to stimuli. The Freudian implied: man is nothing but an elaborate mechanism for discharging primal instincts. Even some cognitive psychologists implied: man is nothing but a computing machine made of meat.

These theories, because they deny any inherent teleological direction in human life — such as an orientation to truth or God —, inevitably miss what is most distinctively human. Robert Brennan, a Thomist author, quipped that many modern psychologists have been “materialists in psychology,” and as materialists “they are bound” to strip man of his spiritual depth and finality.

Inadequacy in Explaining Human Behavior

Perhaps the most practical consequence is that psychology, without final causes, struggles to explain certain basic features of human behavior, especially free, goal-directed action. Human beings routinely act for reasons: I leave my home in order to go to work; I study to gain knowledge or a degree; I comfort a friend because I want to ease her distress. Such purposive explanations are not quirks of folk language — they describe reality.

Yet a psychologist trained to avoid teleological language might rephrase these in convoluted ways or ignore the person’s stated reasons altogether. As Magda Arnold points out, a strict behaviorist mindset will assume there must be some prior stimulus or drive for every action, and if we can’t find it, we simply “assume it is there” because of a “prior deterministic conviction.”

The broader point is that efficient causes alone cannot adequately account for many human acts, especially those involving rational choice. Why did a martyr choose to die rather than renounce his faith? Efficient causes (genes, upbringing, neurotransmitters) might give contributing conditions, but they don’t answer what final vision of the good made that sacrifice makes sense to the person. Thomistic thinkers argue that by ignoring the dimension of final causality — the ends and goods motivating behavior — psychology can do no more than provide data for physiology or biology or ecology, so it cannot properly explain human actions.

A Call for Reintegrating Purpose

In conclusion, the absence of teleology in modern psychology leaves it blind to the most essential aspect of human life: our natural orientation toward meaningful ends. By reclaiming the full explanatory power of the four causes, and especially the final cause, Thomistic psychology offers a path toward a more comprehensive, humane, and philosophically grounded science of the person. Such a reorientation does not diminish scientific rigor; on the contrary, it provides the integrative vision needed to make sense of the scattered insights of empirical research, enabling psychology to guide human beings toward their ultimate flourishing.

Nicolás Eyzaguirre Bäuerle

Editor-in-chief