The Troubling Foundations of Psychology
Modern psychology, as we know it, is built on the triumphs of empirical research: experiments, measurements, brain scans, and behavioral analyses. But beneath this scientific surface lies a deeper philosophical tension that has troubled thinkers for decades. From a Thomistic perspective, two core problems haunt contemporary psychology: positivism and scientific reductionism.
These concepts are more than abstract academic terms; they shape the very questions psychology asks, the methods it values, and the answers it dares to offer. While they have delivered certain empirical successes, they also risk hollowing out psychology’s grasp of human nature, turning it into what critics call a “psychology without a soul.” In this article, we explore why these philosophical foundations trouble psychology and what a corrective integration of philosophy and science might look like.
What Are Positivism and Scientific Reductionism?
Positivism
Positivism, as outlined by figures like John Stuart Mill, asserts that only empirical-sensory data yield valid knowledge. In psychology, this means that anything non-observable — like metaphysical notions of the soul or inherent human purpose — is dismissed as speculative, unscientific, or meaningless. This creates a domain where psychological science is restricted to phenomena that can be measured, observed, and quantified.
In contrast, the Aristotelian-Thomistic tradition, while agreeing that all human knowledge begins in sensory experience, holds that the intellect possesses the capacity to abstract universal and necessary notions from particular and contingent things. Thus, we can know realities that are not directly accessible to the senses — for example, the existence of the soul or God.
Scientific Reductionism
When it comes to psychology, reductionism takes positivism one step further, insisting that human phenomena (thoughts, emotions, decisions) can and should ultimately be explained in terms of physical processes: neurons firing, hormones circulating, or computational patterns in the brain. Robert E. Brennan and Hubert Gruender identify this reductionism as a driving force behind psychology’s materialistic turn — stripping away layers of human interiority in favor of mechanistic models. As a consequence, the human being came to be seen as a purely material entity.
In the words of Arnold and Gasson, man was reduced to a “sophisticated statue,” possessing no faculties beyond complex mechanical systems governed by physico-chemical laws. An example of this is classical Freudian psychoanalysis, in which the human being is reduced to an organism ruled by biological drives (Eros and Thanatos), with no reference to a free rational soul; or in radical behaviorism (Watson, Skinner), when it denies the reality of subjective mental states, treating them as epiphenomena without scientific importance.
Why Is This Troubling?
Loss of the Soul
Thomistic philosophy understands the human being as a unity of body and soul, where the soul (anima) is the form and life principle of the body. Contemporary psychology, by discarding the notion of a substantial soul because “it cannot be seen or touched,” reduces human experience to a mere “flow” of conscious phenomena or neural activity, as William James famously described. This, Mercier argues, leaves us unable to account for personal identity, intentionality, or the unity of consciousness over time.
Without a grounding substantial principle, how do we explain the enduring “I” that persists through changing experiences? How do we connect cognition, emotion, and volition as coordinated faculties rather than fragmented processes?
Incomplete Models of the Person
Returning to psychoanalysis and behaviorism, it is true that their incomplete understanding of the human being has been largely rendered obsolete, but their replacements are not free from the same problems. If scientific reductionism prevents psychology from reaching deeper understandings of phenomena such as the mind, this means that our comprehension of psychopathologies is also obscured.
This legitimizes Pope Pius XII’s concern when, during the First General Assembly of the Collegium Internationale Neuro-Psycho-Pharmacologicum (1958), he wondered: “Does psychotherapeutic medication truly act upon the cause of the illness, or does it merely modify, more or less temporarily, certain symptoms, leaving intact the deep causes at the root of the disorder? To what extent are certain alterations of the central nervous system the origin or the consequence of the emotional disorders that accompany them?”
Fragmentation and Loss of Integration
Without philosophical grounding, psychology risks fragmentation. Cognitive psychology studies thinking; affective neuroscience studies emotions; behavioral science tracks actions. But who ties these strands together into a coherent picture of the person? As Brennan puts it, modern psychology has struggled to achieve “unity” precisely because it has severed itself from the philosophic wisdom of the classical tradition.
Since there is no agreement on what the human mind is or how it works, it is not possible to develop a coherent theory that achieves consistent results in practice — that is to say, one that proves effective in preventing and treating various conditions. On the other hand, this loss of integration hinders scientific communication, confusing students (who learn divergent models), as each approach tends to focus on isolated parts in a reductionist manner.
Toward a Philosophically Informed Psychology
Reintroducing Metaphysics
The Thomistic corrective is not to reject empirical science but to recontextualize it. Psychology needs a philosophical framework that recognizes the human being for what it is: a being whose material and immaterial dimensions are intimately intertwined. Only with such a framework can empirical findings be properly situated, avoiding both positivism and scientific reductionism.
In other words, thanks to this integration psychology can avoid assumptions that, in Mercier’s words, “cannot provide a solution to the essential problems” of the human mind.
Nicolás Eyzaguirre Bäuerle
Editor-in-chief
