Franz Brentano – 1838 1917

Biography

Few thinkers in the nineteenth century occupied an intellectual crossroads as consequential, contested, and enduring as Franz Brentano (1838–1917). Standing at the precise historical juncture where late medieval scholasticism converged with British empiricism, German Idealism, and the nascent methodologies of natural science, Brentano fundamentally reshaped the course of European philosophy. While contemporary discourse frequently remembers him as the philosophical spark behind the modern rediscovery of intentionality, his legacy is not merely that of a precursor to Edmund Husserl or an early influence on Sigmund Freud. Brentano was the architect of an ambitious, unified philosophical program that sought to rescue metaphysics and epistemology from speculative obscurity by anchoring them in a rigorous, empirical science of the mind.

Brentano’s philosophical project was defined by an uncompromising conviction: philosophy must share the same foundational method as the natural sciences, proceeding through careful observation, systematic description, and rigorous logical induction, rather than through sweeping a priori deductions. This methodological imperative drove him to reconstruct psychology from the ground up, not as a purely physiological or mechanistic investigation of neurological reflexes, but as a descriptive morphology of conscious acts. By centering intentionality—the fundamental directedness of consciousness toward an object—Brentano supplied modern philosophy with the foundational vocabulary required to investigate the nature of representation, judgment, affective valuation, and the unified structure of subjective experience.

Beyond his revolutionary contributions to empirical psychology and the philosophy of mind, Brentano’s intellectual footprint extends through ontology, ethics, semantics, and natural theology. His early investigations into the manifold senses of being in Aristotle profoundly shaped twentieth-century continental ontology, serving as the decisive catalyst for the young Martin Heidegger. Simultaneously, his late conversion to reism—a radical nominalist ontology maintaining that only concrete, individual things exist—anticipated core concerns of contemporary analytic metaphysics and ordinary language philosophy. To explore Brentano’s thought is to trace the hidden institutional, methodological, and conceptual arteries connecting classical Western thought with the twin movements of contemporary phenomenology and analytic philosophy.

1. Biographical Foundations and Intellectual Formation (1838–1874)

1.1 Early Life, Family Background, and Education

Franz Clemens Honoratus Hermann Brentano was born on January 16, 1838, in Marienberg near Boppard on the Rhine, into an illustrious German-Italian Catholic family deeply intertwined with German literary and cultural history. He was the son of the Catholic writer and historian Christian Brentano and the nephew of two luminaries of the German Romantic movement: the poet Clemens Brentano and the writer Bettina von Arnim (née Brentano). This lineage provided the young Franz with an upbringing steeped in rich intellectual engagement, rigorous Roman Catholic piety, and a sophisticated appreciation for humanistic inquiry. His brother, Lujo Brentano, would later become an acclaimed political economist, highlighting the exceptional academic and cultural vitality that characterized the Brentano household.

Brentano received his early schooling at the Gymnasium in Aschaffenburg, where he demonstrated an extraordinary aptitude for classical languages, mathematics, and Christian theology. During this formative period, his intellectual temperament was shaped by an intense, disciplined immersion in scholastic thought. Unlike many of his German contemporaries who were enthralled by the fading twilight of post-Kantian German Idealism, Brentano was introduced early to the rigorous conceptual categories of St. Thomas Aquinas and the broader medieval Aristotelian tradition. This scholastic foundation instilled in him a lifelong commitment to terminological clarity, systematic categorization, and the belief that metaphysical inquiry must be conducted with analytical precision.

His university studies began in 1856 and spanned the preeminent centers of German academia, including Munich, Würzburg, Berlin, and Münster. At the University of Berlin, Brentano fell under the profound mentorship of Adolf Trendelenburg, one of the most distinguished Aristotelian scholars of the nineteenth century. Trendelenburg’s philological rigor and his insistence on the vital relevance of classical Greek thought over and against Hegelian dialectics left an indelible mark on Brentano’s intellectual trajectory. In Münster, Brentano pursued advanced studies in theology and scholastic metaphysics under Franz Jakob Clemens, further refining his grasp of Catholic doctrine and medieval ontology.

The culmination of these early academic endeavors was Brentano’s doctoral dissertation, completed at the University of Tübingen in 1862, titled Von der mannigfachen Bedeutung des Seienden nach Aristoteles (On the Several Senses of Being in Aristotle). In this landmark work, Brentano demonstrated not only an unparalleled philological mastery of the Aristotelian corpus but also an innovative philosophical capacity to organize Aristotle’s disparate ontological categories into a coherent metaphysical schema. The dissertation was celebrated for its lucidity and depth, laying the groundwork for Brentano’s future investigations into ontology and establishing his reputation as one of the most promising young philosophers in the German-speaking world.

1.2 Priesthood, Ecclesiastical Conflicts, and Resignation

Following the completion of his doctoral studies, Brentano felt an intense inner vocational calling that fused his philosophical aspirations with spiritual service. He entered the Dominican-influenced seminary in Mainz and was formally ordained into the Catholic priesthood on August 6, 1864. Brentano viewed his clerical vocation not as a withdrawal from intellectual inquiry, but as the supreme integration of philosophical pursuit and Christian caritas. Shortly after his ordination, he completed his Habilitation at the University of Würzburg in 1866, with a thesis titled Die Psychologie des Aristoteles, insbesondere seine Lehre vom nous poietikos (The Psychology of Aristotle, in Particular His Doctrine of the Active Intellect), subsequently securing an appointment as a Privatdozent in the university’s philosophy faculty.

During his early years at Würzburg, Brentano immersed himself deeply in the study of Catholic dogma, patristic literature, and medieval epistemology. He was an exceptionally popular and charismatic lecturer, captivating audiences with his dynamic rhetorical style and his insistence that philosophy possessed vital, life-orienting significance. However, this period of academic flourishing coincided with severe theological tensions within the Roman Catholic Church. The late 1860s were marked by the growing ascendancy of the Ultramontane movement, which culminated in the convocation of the First Vatican Council (1869–1870) under Pope Pius IX.

Brentano became a central intellectual figure in the resistance against the proposed dogma of Papal Infallibility. Working closely with prominent liberal Catholic theologians such as Ignaz von Döllinger and Bishop Wilhelm Emmanuel von Ketteler, Brentano authored an exhaustive, scientifically grounded memorandum commissioned by Bishop Ketteler. In this treatise, Brentano mobilized historical, patristic, and scriptural evidence to demonstrate that the doctrine of ex cathedra papal infallibility lacked legitimate precedent in the early Church and posed grave dangers to theological integrity and intellectual freedom.

When the First Vatican Council officially promulgated the dogma of Papal Infallibility in the dogmatic constitution Pastor Aeternus in July 1870, Brentano faced an agonizing crisis of conscience. While many dissenting scholars accommodated themselves to the decree or established the schismatic Old Catholic Church, Brentano rejected half-measures. He concluded that his intellectual honesty and philosophical principles were fundamentally incompatible with the submission demanded by the Church hierarchy. After a protracted period of spiritual anguish and unsuccessful reconciliation, Brentano formally renounced the priesthood and his religious vows in April 1873. This rupture caused profound personal grief, estranged him from conservative colleagues and family members, and precipitated his departure from the faculty at Würzburg, where a clerical status had been intimately bound to his academic standing.

1.3 The Professorship in Vienna and Academic Environment

Brentano’s release from ecclesiastical obligations cleared the path for a new chapter in his philosophical career. In 1874, through the intervention of progressive Austrian reformers and academic champions such as the philosopher Robert von Zimmermann, Brentano was appointed to the prestigious position of Full Professor of Philosophy at the University of Vienna. The year 1874 proved to be Brentano’s annus mirabilis; alongside his arrival in Vienna, he published his seminal masterpiece, Psychologie vom empirischen Standpunkte (Psychology from an Empirical Standpoint). This monumental work signaled a programmatic shift in European philosophy, presenting an empirical, act-centered psychology designed to serve as the rigorous foundation for all philosophical disciplines.

The academic environment in Vienna during the 1870s and 1880s was an extraordinarily fertile ground for intellectual revolution. Free from the stifling scholastic orthodoxy of Würzburg and the lingering dogmas of German Idealism that still held sway in parts of Prussia, the University of Vienna was becoming a cosmopolitan crossroads of modernity. Brentano’s lectures quickly became cultural and intellectual events, drawing students from philosophy, jurisprudence, natural sciences, and literature. His pedagogical approach was participatory, demanding, and dialectical. He discouraged passive memorization, challenging his students to analyze subjective experiences directly and engage in unrelenting conceptual critique.

Brentano’s tenure as a full professor, however, was abruptly derailed in 1880 by institutional and legal complications surrounding Austrian marriage laws. Brentano sought to marry Ida Lieben, a member of an influential Viennese Jewish family who had converted to Catholicism. Under Austrian law, individuals who had ever been ordained into the Catholic priesthood—regardless of their subsequent secularization or resignation—were legally prohibited from marrying. To circumvent this restriction, Brentano made the drastic decision to renounce his Austrian citizenship and relocate briefly to Saxony, where he acquired citizenship and was married in April 1880.

Upon his return to the University of Vienna, the Austrian conservative authorities and ecclesiastical sympathizers retaliated. Brentano was stripped of his full professorship and reduced to the status of an unpaid Privatdozent. Despite this professional demotion and the subsequent loss of a formal pension and institutional authority, Brentano continued to teach in Vienna for an additional fifteen years. The sheer magnetism of his thought and character sustained an intellectual circle of unparalleled historical importance. In this vibrant circle sat figures who would dictate the trajectory of twentieth-century philosophy, psychology, and logic: Edmund Husserl, Alexius Meinong, Christian von Ehrenfels, Carl Stumpf, Anton Marty, Kazimierz Twardowski, and a young medical student named Sigmund Freud.

2. Aristotelian Roots and Early Metaphysical Studies

2.1 The Manifold Senses of Being in Aristotle

The foundation of Brentano’s entire philosophical architecture rests upon his engagement with the ontology of Aristotle. In his 1862 dissertation, Von der mannigfachen Bedeutung des Seienden nach Aristoteles, Brentano addressed one of the most perplexing problems in ancient metaphysics: if being (to on) is said in many ways, what unifies these disparate meanings, and how can there be a single, systematic science of being qua being? Brentano’s resolution of this problem was both an interpretive tour de force and an original contribution to metaphysical theory.

Following Aristotle’s Metaphysics, Brentano organized the manifold senses of being into a rigorous fourfold classification:

• Accidental being (ens per accidens / kata symbebekos): That which belongs to a thing only incidentally or contingently, such as a musician who happens to be a builder. Accidental being cannot be the subject of a rigorous theoretical science because it lacks internal necessity and systematic lawful structure.
• Being as truth (ens tanquam verum / hos alethes): The sense of being operative in propositional assertions, where “is” signifies the truth of an affirmation and “is not” signifies the truth of a denial. Here, being resides not primarily in the objective reality of things, but in the judging intellect that correctly unites or separates concepts.
• Being according to the figures of the categories (ens per se / kata ta schemata ton kategorion): The primary ontological articulation of reality into substance and its various accidents—quality, quantity, relation, place, time, position, state, action, and passion.
• Potential and actual being (ens potentiale et actuale / dynamei kai energeia): The dynamic modal distinction that cuts across all categories, explaining motion, generation, transformation, and teleological fulfillment in the cosmos.

Brentano argued that the ultimate unity of these four senses is grounded in the ontological priority of substance (ousia). Every category of accident, every instance of potentiality, and every propositional truth fundamentally refers back to substance as the primary bearer of reality. Accidental being is intelligible only because it inheres in a substance; potentiality is always the potentiality of a substance to actualize a form; and the truth of propositions corresponds ultimately to states of affairs grounded in real, substantial unities.

The historical importance of Brentano’s dissertation cannot be overstated. In the summer of 1907, an eighteen-year-old gymnasium student named Martin Heidegger received a copy of Brentano’s dissertation from his mentor, Father Conrad Gröber. Heidegger’s deep confrontation with Brentano’s analysis of Aristotle’s question—”If being is said in many ways, what is its decisive, guiding meaning?”—served as the primary catalyst for his own lifelong pursuit of the question of Being (Seinsfrage), culminating in his 1927 magnum opus, Being and Time. Brentano’s rigorous structural analysis re-opened the classical metaphysical landscape for the modern continental tradition.

2.2 Psychology and Noetics in Aristotle

Building directly upon his ontological investigations, Brentano turned his attention in 1867 to ancient philosophical anthropology and cognitive theory with his treatise Die Psychologie des Aristoteles. In this work, Brentano offered an exhaustive commentary on Aristotle’s De Anima, focusing on the notoriously enigmatic third book concerning human noetics—specifically the nature of the intellect and its capacity for theoretical cognition.

Central to Brentano’s reading was the rigorous differentiation between the active intellect (nous poietikos) and the passive or receptive intellect (nous pathetikos). Aristotle had asserted that while the senses receive the sensible forms of objects without their matter, the intellectual soul must possess a capacity to apprehend universal essences. Brentano analyzed how the passive intellect, which is potentially all intelligible forms, is illuminated and actualized by the active intellect. Drawing heavily upon Aquinas’s interpretations while critiquing Averroes’s doctrine of a single, monopsychic universal intellect, Brentano argued that the active intellect is an inherent, immaterial, and indivisible power of the individual human soul.

Crucially, Brentano’s treatment of Aristotle’s psychology integrated empirical observation with teleological hylomorphism. For Aristotle, the soul (psyche) is the form (eidos) of a natural organic body possessing the potentiality for life. Brentano demonstrated how this hylomorphic framework provided a viable third way between crude materialism, which fails to account for the qualitative uniqueness and intentional directedness of mental acts, and extreme Cartesian dualism, which creates an unbridgeable metaphysical chasm between the physical body and the thinking mind. In Aristotle, Brentano found an organic, integrated view of human life where biological functions and cognitive operations form a continuous, hierarchically ordered spectrum.

This engagement with Aristotle cemented Brentano’s vehement rejection of post-Kantian German Idealism, especially the dialectical systems of Fichte, Schelling, and Hegel. Brentano viewed the speculative excesses of idealism as disastrous departures from empirical realism, intellectual clarity, and classical metaphysics. Instead of deducing the world from transcendental egos or absolute spirits, philosophy had to return to an observational realism that honored the distinct structural features of the empirical world while retaining the capacity for rational, metaphysical demonstration.

2.3 Methodological Tenet: The Unity of Scientific Method

When Brentano defended his Habilitation theses at the University of Würzburg in 1866, he included a proposition that would become the foundational rallying cry for his entire pedagogical and philosophical career. His famous fourth thesis read: “Vera philosophiae methodus nulla alia nisi scientiae naturalis est”—The true method of philosophy is none other than that of the natural sciences.

This programmatic assertion was not an endorsement of nineteenth-century mechanistic materialism, nor did it suggest that philosophical questions could be entirely resolved by physics or chemistry. Rather, Brentano was asserting the formal and methodological unity of all scientific inquiry. For Brentano, a genuine science is characterized by:

• The rejection of pure apriorism, mystical intuition, and dogmatic speculation;
• A foundational reliance on systematic empirical observation and concrete experience;
• The rigorous application of inductive logic, moving carefully from observed particulars to general laws;
• The demand for conceptual clarity, precise definitions, and logical coherence in argumentation.

Brentano viewed the history of philosophy through a cyclical theory of development and decay. A philosophical tradition begins with a period of healthy, empirical, and scientific inquiry (exemplified by classical Greece and Aristotle). This is inevitably followed by a period of practical and ethical application (the Stoics and Epicureans), which subsequently decays into a third phase of skepticism. Finally, the tradition collapses into a fourth phase of mystical, speculative, and unscientific philosophy (exemplified by Neo-Platonism in antiquity and German Idealism in the modern era). Brentano believed that nineteenth-century philosophy was trapped in the destructive wake of Hegelianism and Romantic obscurantism. To rescue philosophy from intellectual bankruptcy, it had to be re-established as a rigorous science (strenge Wissenschaft), adopting the empirical ethos, cautious induction, and methodological discipline that had propelled the natural sciences to unprecedented success.

3. The Program of Empirical Psychology

3.1 Psychology from an Empirical Standpoint (1874)

The definitive realization of Brentano’s methodological program arrived in 1874 with the publication of his masterwork, Psychologie vom empirischen Standpunkte. With this text, Brentano sought to establish psychology as an autonomous, scientifically rigorous discipline capable of serving as the foundation for epistemology, logic, ethics, and aesthetics. At the core of this enterprise was a critical redefinition of the subject matter of psychology itself. Brentano firmly rejected the traditional metaphysical conception of psychology as the “science of the soul” (Seelenlehre). To define psychology as the science of a substantial, immortal soul-substance was, in his view, to prejudge a metaphysical question that could not be settled at the outset of empirical inquiry. Instead, Brentano defined psychology strictly as the science of mental phenomena (Wissenschaft von den psychischen Phänomenen).

To establish this science, Brentano introduced an absolute and exhaustive demarcation between two classes of phenomena given in human experience: mental phenomena (psychische Phänomene) and physical phenomena (physische Phänomene). Brentano’s taxonomy delineated mental phenomena as acts of experiencing: hearing a sound, seeing a color, feeling a sensation of warmth, remembering an event, forming an abstract concept, making an affirmation, or feeling joy or sorrow. In sharp contrast, physical phenomena are the contents presented to our sensations: the sound that is heard, the color that is seen, the warmth that is felt, or a spatial figure perceived in the visual field.

This demarcation served as a direct critique of the emerging school of psychophysics, championed by figures like Gustav Fechner, Hermann von Helmholtz, and the experimental laboratory model pioneered by Wilhelm Wundt. While Brentano recognized the value of measuring physical stimuli and physiological response thresholds, he warned against absolute physiological reductionism. Psychology, he insisted, could never be reduced to the mechanical movement of nerve fibers or electrical impulses in the brain. Physical phenomena are secondary and mediate, whereas mental phenomena possess a unique, irreducible structural reality: they are experiential acts. By prioritizing descriptive, phenomenological analysis of these mental acts, Brentano asserted that immediate experience is the primary and indispensable foundation of all psychological science.

3.2 Inner Perception versus Inner Observation

Having defined psychology as the science of mental phenomena, Brentano confronted a formidable epistemological dilemma: how can mental phenomena be scientifically investigated without succumbing to the fatal pitfalls of subjective introspection? The French positivist philosopher Auguste Comte had issued a celebrated challenge against the possibility of psychological introspection, arguing that the thinking mind cannot split itself into two parts, one observing and the other being observed. If an individual attempts to observe their own conscious anger, the very act of cool, reflective observation immediately dissipates the anger, thus destroying the object under investigation.

Brentano resolved this paradox through a subtle yet foundational distinction between inner observation (innere Beobachtung) and inner perception (innere Wahrnehmung):

Inner observation involves a deliberate, intentional turning of attention toward one’s ongoing mental acts. Brentano agreed entirely with Comte that direct inner observation is impossible. One cannot simultaneously experience a violent burst of rage and objectively focus analytical attention upon that rage without altering or extinguishing it. The intentional target of an act of observation cannot be the very act that is occurring at that precise moment.

In contrast, inner perception is never an isolated, direct act of focused attention. Rather, it is a secondary, reflexive awareness that accompanies every mental act intrinsically. When I hear a musical tone, my attention is directed at the tone (the primary object). Simultaneously, however, I possess an immediate, non-observational, and indubitable awareness of my own act of hearing (the secondary object). This inner perception occurs effortlessly and unreflectively alongside the mental act. Brentano insisted that inner perception possesses an extraordinary epistemic status: it is characterized by immediate evidential certainty and infallibility. While my external perception of a physical object may be an illusion or hallucination, I cannot be mistaken about the immediate fact that I am experiencing a perceptual representation of that object.

To conduct empirical psychological science without inner observation, Brentano pointed to two reliable methodologies: the retrospective analysis of memory (observing the vivid memory trace of a mental act immediately after it has transpired) and the systematic descriptive analysis of the necessary structures revealed through inner perception.

3.3 Rejection of the Unconscious Mind

A crucial and fiercely defended corollary of Brentano’s empirical psychology was his absolute rejection of the concept of the unconscious mind. In the late nineteenth century, theories of the unconscious were gaining immense popularity throughout Europe, championed most prominently by Eduard von Hartmann in his widely read 1869 work Philosophie des Unbewussten (Philosophy of the Unconscious) and later institutionalized in psychoanalytic models.

Brentano subjected every argument for the existence of unconscious mental states to an exhaustive, trenchant critique. He argued that the phrase “unconscious mental phenomenon” was an oxymoronic contradiction in terms. By its very definition, a mental phenomenon is an act that is experienced; and as established by his doctrine of inner perception, every mental act necessarily contains within itself an immediate, secondary awareness of its own occurrence. There can be no hearing that is not accompanied by the inner awareness of hearing, no desiring without the inner awareness of desiring. If an act is devoid of all conscious awareness, it ceases to possess the structural features of a mental phenomenon and must instead be classified as a purely physiological or bodily process.

How, then, did Brentano explain the empirical phenomena that led other theorists to postulate an unconscious mind—phenomena such as forgotten memories suddenly resurfacing, habitual automatic actions, or subliminal perceptual cues? Brentano offered a twofold explanation grounded in:

• Degrees of intentional intensity and attention: Many conscious mental acts occur with such low intensity or amidst such a chaotic cacophony of competing stimuli that they pass without focused reflection. They are fully conscious in the strict sense of inner perception, but they fail to trigger subsequent acts of memory or conceptual recognition.
• Unnoticed representations and physiological causality: Mental phenomena are linked causally through underlying neurophysiological structures. When a memory suddenly reappears after years of absence, it is not because an “unconscious idea” was lurking beneath the surface of the mind; rather, physiological neural processes operated mechanistically to produce a newly conscious mental representation in response to a fresh stimulus.

4. Intentionality and the Mark of the Mental

4.1 The Re-Discovery and Redefinition of Intentionality

The single most enduring contribution of Franz Brentano to modern philosophy is his re-discovery and radical reform of the concept of intentionality. While the term originated in medieval Scholastic philosophy—particularly in the writings of Thomas Aquinas, Duns Scotus, and Peter Auriol, who used intentio to describe the mental concept or form through which the mind apprehends reality—Brentano extracted this historical term from scholastic obscurity and transformed it into the bedrock of modern philosophical psychology.

In what is arguably the most famous paragraph written in nineteenth-century Austrian philosophy, Brentano formulated the defining criterion of mental life in Psychology from an Empirical Standpoint (1874):

“Every mental phenomenon is characterized by what the Scholastics of the Middle Ages referred to as the intentional (or mental) inexistence of an object, and what we might call, though not wholly unambiguously, reference to a content, direction toward an object (which is not to be understood here as meaning a thing), or immanent objectivity. Every mental phenomenon includes something as object within itself, although they do not all do so in the same way. In presentation something is presented, in judgment something is affirmed or denied, in love loved, in hate hated, in desire desired, and so on. This intentional inexistence is characteristic exclusively of mental phenomena. No physical phenomenon exhibits anything like it. And thus we can define mental phenomena by saying that they are those phenomena which contain an object intentionally within themselves.”

This formulation, known historically as Brentano’s Thesis, posited intentionality—the inherent “aboutness” or directedness of consciousness toward an object—as the absolute mark of the mental (das Kriterium des Psychischen). A rock, a wave, or a chemical reaction is simply what it is; it does not point toward, refer to, or contain an idea of anything outside itself. In contrast, mental acts cannot exist in complete isolation: they are intrinsically relational structures. Consciousness is never an empty container; to be conscious is necessarily to be conscious of something.

4.2 The Problem of the Intentional Object

While Brentano’s declaration provided an intuitive criterion for distinguishing the mental from the physical, it instantly opened a formidable metaphysical and semantic problem that would dominate philosophy of mind for the next century: What is the ontological status of the intentional object?

Brentano’s early phrasing suggested that the intentional object possesses an “immanent objectivity” (immanente Gegenständlichkeit)—meaning that the object exists inside the mental act itself as an intrinsic constituent of consciousness. This interpretation created severe difficulties, particularly regarding non-existent objects, hallucinations, errors, and fictional entities. When a child thinks of Santa Claus, or when an ancient Greek philosopher contemplated Zeus, or when a mathematician contemplates a round square, what is the object of the thought?

• If the intentional object is merely a real, transcendent thing in the external world, then thoughts about non-existent entities would be thoughts about nothing, and thus would not be intentional acts at all.
• If, on the other hand, the intentional object is an “immanent entity” residing within the mind, one faces the absurd conclusion that when I look at a physical tree, I am not perceiving a real, external botanical entity, but merely an internal mental representation of a tree. This threatens to collapse empirical realism into solipsistic phenomenalism.

This profound ambiguity forced Brentano and his disciples into decades of intense debate. Disciples like Alexius Meinong resolved the dilemma by hypostatizing an immense realm of “objects” that do not exist (Nichtsein) but nonetheless possess being as the targets of thought. In stark contrast, Brentano himself vehemently rejected Meinong’s inflation of ontology. As Brentano aged, he abandoned the language of “immanent objectivity,” clarifying that intentionality is not a relation between a mind and an internal mental phantom, but a quasi-relational attitude of the thinking person directed toward real things in the world, even when those things fail to exist.

4.3 Critique and Clarification of Intentional Inexistence

Much of the historical confusion surrounding Brentano’s doctrine stemmed from the linguistic evolution of the term intentional inexistence (intentionale Inexistenz). In modern English and German, the prefix “in-” commonly denotes negation (e.g., in-existence as non-existence). However, Brentano employed the term strictly in its classical Latin scholastic sense: in-existentia signified existing-in (in-esse)—the property of being internally present to or contained within the cognitive act.

Brentano repeatedly clarified that this “existing-in” was not to be understood as physical containment, like a coin residing inside a pocket. Rather, it described an irreducibly cognitive mode of presence. Physical phenomena are observed outwardly through the senses, but they are external and lack self-contained meaning; mental phenomena, by contrast, are directed inwardly toward contents that are presented directly to the subjective mind.

Furthermore, Brentano responded vigorously to contemporary misinterpretations that sought to assimilate intentionality into physiological mechanics. Mechanistic naturalists argued that intentional directedness was merely an evolutionary adaptation of reflex arcs. Brentano counter-argued that no description of electrical nerve conduction, optical geometry, or acoustic vibrations could capture the unique, normatively evaluable, and semantic relation of reference. A physical brain state cannot be “about” an ancient empire or a mathematical theorem. By establishing intentionality as an irreducible, non-physical characteristic of mental phenomena, Brentano laid the structural foundation upon which both 20th-century phenomenological description (Phenomenology) and twentieth-century analytic philosophy of mind would wage their central battles.

5. The Classification of Mental Phenomena

5.1 Representations (Vorstellungen)

Having established intentionality as the universal hallmark of the mental, Brentano undertook the systematic classification of mental phenomena. While classical psychology had often vacillated between dualistic faculties (cognition versus will) or tripartite faculties (intellect, feeling, and will), Brentano introduced a revolutionary, hierarchically organized tripartite division: Representations (Vorstellungen), Judgments (Urteile), and Phenomena of Love and Hate (Gemütsbewegungen or acts of interest).

At the absolute foundation of all mental life stands the Representation (or presentation). Brentano formulated this fundamental priority through a celebrated maxim: Nothing can be judged, nothing can be desired, nothing can be hoped or feared, unless it is first represented. A representation occurs whenever something appears to consciousness. When I see a flash of red light, hear a high-pitched frequency, or imagine a mythological creature, an act of representation has taken place. The defining characteristic of a representation is that it is pure presentation devoid of belief, valuation, endorsement, or rejection.

In an act of simple representation, consciousness merely entertains a content. If I consider the proposition “There is life on Mars” without affirming or denying it, the state of affairs is merely presented to my intellect. Brentano carefully differentiated between:

• Simple sensory presentations: Direct, unconceptualized sensory impressions such as a color patch, an auditory tone, or an olfactory sensation;
• Complex conceptual representations: Abstract notions, semantic meanings, and intellectual constructs such as “justice,” “the prime numbers,” or “a equilateral triangle.”

Crucially, representations provide the indispensable raw material for every higher-order mental act. Representations are non-bivalent: they cannot be true or false, good or bad; they simply present an intentional object to the mind.

5.2 Judgments (Urteile)

The second broad class of mental phenomena comprises Judgments. Brentano’s theory of judgment represents one of his most radical departures from classical logic and philosophical orthodoxy. Since Aristotle, the standard Western model had viewed judgment as a synthesis of concepts—a subject-predicate propositional construction (e.g., “The tree is green”) wherein a predicate is joined to or separated from a subject via a copula.

Brentano categorically rejected this subject-predicate model. He insisted that the true essence of judgment does not consist in the combination or relation of two concepts, but in the acceptance (affirmation) or rejection (denial) of an intentional object. A judgment is an entirely distinct, irreducible mode of consciousness that supervenes upon a representation. First, an object is presented via a representation; second, the intellect either affirms the reality of that object or denies it.

To substantiate this, Brentano developed his famous existential formulation of judgment. Every categorical proposition can be translated without loss of logical meaning into an existential judgment:

• The proposition “God exists” is not the attribution of a predicate (“existence”) to a subject (“God”); it is simply the affirmation of the representation “God.”
• The categorical proposition “All men are mortal” does not unite two concepts; it is the rejection or denial of the concept of an “immortal man” (There is not an immortal man: Ein unsterblicher Mensch ist nicht).
• The universal negative proposition “No stones are living” is the denial of the representation “living stone.”

Thus, for Brentano, all judgments are existential judgments of the form “A is” (affirming A) or “A is not” (denying A). Furthermore, judgments possess an intrinsic bivalence: they are fundamentally characterized by the polarity of affirmation versus negation, and they can be evaluated objectively as either true or false, correct or incorrect, depending on their alignment with evident reality.

5.3 Phenomena of Love and Hate (Gemütsbewegungen)

The third and final class of mental phenomena encompasses what Brentano broadly designated as the Phenomena of Love and Hate (Gemütsbewegungen), spanning the entire affective and volitional life of the human subject: sensations of pleasure and pain, emotions, passions, desires, hopes, fears, moral decisions, and deliberate acts of will. By consolidating emotions and volitions into a single fundamental category, Brentano broke decisively with the Kantian trichotomy that rigidly separated feeling from willing.

Brentano argued that emotions and volitions share an identical basic intentional structure. Just as every judgment accepts or rejects an object presented by a representation, every affective or volitional act adopts an evaluative attitude of attraction or aversion toward an intentional object:

• In love (broadly understood as approval, attraction, delight, or desire), the mind responds positively toward the presented content.
• In hate (understood as disapproval, aversion, sorrow, or repulsion), the mind responds negatively toward the presented content.

Crucially, Brentano identified an exact, rigorous structural analogy between the domain of judgment and the domain of emotion:

Just as a judgment does not merely represent an object but holds it to be true or false, an emotion does not merely register a representation but holds it to be good or bad. This structural insight formed the bedrock of Brentano’s revolutionary moral philosophy and axiological theory.

6. Descriptive Psychology versus Genetic Psychology

6.1 Foundations of Descriptive Psychology (Psychognosy)

In the late 1880s and early 1890s, particularly during his celebrated Vienna lecture courses, Brentano introduced a methodological refinement that fundamentally reshaped his scientific program: the explicit division of psychology into two completely distinct yet complementary branches: Descriptive Psychology (which he termed Psychognosie) and Genetic Psychology (genetische Psychologie).

Descriptive psychology (Psychognosy) is the pure morphology, taxonomy, and structural analysis of conscious mental phenomena as they are immediately given in inner experience. Its objective is not to explain how a mental act comes into being, what physical brain mechanisms generate it, or what biological utility it serves. Rather, its sole task is to provide an exact, comprehensive, and logically systematic description of the elements and structures of human consciousness. Psychognosy is an a priori, apodictic, and exact science. Like geometry or arithmetic, which can establish immutable axioms regarding shapes or numbers without conducting physical experiments, descriptive psychology discovers necessary laws governing the relations between conscious phenomena—for instance, the law that no judgment or emotional act can occur without an underlying representation.

To execute this descriptive task, Brentano developed a sophisticated method of mereological analysis—the formal theory of parts and wholes. Within conscious experience, Brentano distinguished between separable parts (parts that can exist independently of the whole, such as two distinct musical tones heard sequentially) and non-separable or distinguished parts (moments that cannot exist in isolation, such as the color of a surface and its spatial extension, or an act of judgment and the presentation upon which it is founded). Descriptive psychology maps these structural invariants with mathematical precision, completely independent of physiological conditions.

6.2 The Domain of Genetic Psychology

In contrast to the structural purity of psychognosy, Genetic Psychology is an empirical, causal, and explanatory science. Its goal is to uncover the causal conditions, physiological mechanisms, biological origins, and developmental trajectories that govern the actual appearance and succession of mental phenomena in real-world organisms.

Genetic psychology investigates questions such as:

• How do sensory organs and neural pathways process physical energy into sensation?
• What biological and chemical factors determine the decay of memory traces over time?
• How do psychological associations, trauma, and bodily fatigue influence human cognition and decision-making?

Because genetic psychology depends on physical measurements, neuroanatomy, animal behavior studies, and laboratory experimentation, it belongs firmly to the empirical natural sciences. Consequently, its findings lack the absolute, apodictic certainty of psychognosy; its conclusions are inductive, empirical generalizations, subject to statistical probability, empirical revision, and scientific fallibility.

Crucially, Brentano asserted the absolute methodological priority of descriptive psychology over genetic psychology. One cannot meaningfully search for the causal brain mechanisms of “judgment,” “emotion,” or “memory” without first having an exact, logically rigorous description of what judgment, emotion, and memory actually are in conscious experience. To pursue brain science without prior psychognostic taxonomy is to blindly hunt for the physiological causes of undefined phenomena.

6.3 Influence on Descriptive Science and Methodology

Brentano’s formulation of descriptive psychology sent seismic shockwaves through European intellectual life, directly establishing the methodological paradigms of both phenomenology and Gestalt psychology. The most immediate beneficiary was his student, Edmund Husserl. Husserl took Brentano’s descriptive psychology, stripped it of its remaining naturalistic psychological assumptions, and converted it into the foundation of transcendental phenomenology in his Logical Investigations (1900–1901), explicitly crediting Brentano with reviving the descriptive analysis of intentional acts.

Simultaneously, Carl Stumpf—another of Brentano’s brilliant early students—applied the psychognostic method to acoustic perception in his groundbreaking work Tonpsychologie (Psychology of Tone, 1883–1890). Stumpf demonstrated that auditory experiences could not be understood through mere mechanical analysis of sound waves or atomistic sensory components; rather, conscious experience reveals inherent relational structures, fusion of tones, and irreducible qualitative wholes. Stumpf went on to found the Berlin psychological laboratory, mentoring the founders of Gestalt psychology: Max Wertheimer, Wolfgang Köhler, and Kurt Koffka.

The anti-atomistic, mereological character of Brentano’s descriptive psychology thus dealt a fatal blow to the classical British associationism of John Locke, David Hume, and James Mill. The mind was no longer viewed as a passive mosaic of atomic sensory impressions mechanically glued together by habit; it was recognized as an active, structured, mereological unity governed by internal phenomenological laws.

7. Brentano’s Epistemology and Inner Consciousness

7.1 Primary and Secondary Objects of Consciousness

One of the most elegant and technically profound dimensions of Brentano’s philosophical psychology is his resolution of the problem of inner consciousness (inneres Bewusstsein). If every mental act is directed intentionally toward an object, what happens when we are conscious of our own mental acts? If an act of hearing requires a second act of thinking to become aware of the hearing, and that second act requires a third act to be known, philosophy falls immediately into an unviable infinite regress.

Brentano solved this ancient riddle by demonstrating that consciousness possesses an intrinsic dual-aspect structure within a single, unified mental act. When an individual hears a musical tone, the conscious act is not doubled or multiplied. Rather, the single, undivided act is directed simultaneously toward two distinct objects:

• The primary object (primärer Gegenstand): The external content or phenomenon toward which attention is overtly directed—in this case, the musical tone.
• The secondary object (sekundärer Gegenstand): The mental act itself—the act of hearing the tone.

In this single mental event, the tone is represented as the primary object, while the mental act of hearing is apprehended reflexively, immediately, and non-observationally as the secondary object. Because the act represents itself from within, no secondary act of monitoring is required. The hearing and the awareness of hearing are structurally fused in a single intentional event:

“The presentation of the sound and the presentation of the presentation of the sound form but a single mental act… which in itself exhibits a twofold aspect.”

Through this ingenious model, Brentano eliminated the threat of infinite regress, establishing that conscious experience is intrinsically self-intimating, self-revealing, and non-relationally aware of its own occurrence.

7.2 Evidence and the Criterion of Truth

Brentano’s epistemological framework is anchored in an uncompromising rejection of the traditional correspondence theory of truth, at least in its naive pictorial form (adaequatio intellectus et rei). The idea that truth consists in a pictorial copying or structural mirroring between an internal mental image and an external physical object was, for Brentano, entirely untenable. We can never step outside of our own consciousness to compare a mental representation with a completely transcendent, unexperienced object in itself.

Instead, Brentano grounded the nature of truth in the immediate, qualitative character of Evidence (Evidenz). Brentano drew a sharp epistemological distinction between two modes of judgment:

• Blind judgments (blinde Urteile): Judgments formed through prejudice, casual induction, unexamined habit, authority, or instinctive belief. A blind judgment may happen to be factually true (for instance, guessing correctly that it is raining in Tokyo), but it lacks rational clarity and internal epistemic warrant. It feels like an arbitrary psychic compulsion.
• Evident judgments (evidente Urteile): Judgments accompanied by the luminous, unmistakable clarity of direct rational insight. In an evident judgment, the truth of the state of affairs is apprehended with immediate certainty; deception is not merely unlikely, but intrinsically impossible.

Brentano famously anchored this criterion of truth in the Cartesian bedrock of inner perception. When I experience a conscious act of pain or doubt, my judgment that “I am currently experiencing this act” is accompanied by absolute, infallible evidence. I can doubt the external existence of a physical world, but I cannot doubt the immediate, evident occurrence of my own present mental states. For Brentano, truth is defined in relation to the evident judgment of an ideal epistemic agent: a proposition is true if and only if it would be affirmed by an intellect judging with complete and perfect evidence.

7.3 Memory, Induction, and the Limits of Evidential Knowledge

While inner perception provides an unassailable foundation of absolute evidence, Brentano was deeply cognizant of the severe epistemic boundaries surrounding human knowledge. Beyond the immediate, present moment of inner perception, absolute evidence ceases, and epistemic fallibility begins.

First, Brentano emphasized the fallibility of memory. Even though a mental act was perceived with absolute certainty at the exact instant of its occurrence, the moment it passes into memory, it is no longer given with original, apodictic evidence. Memory preserves a representation of a past act, but the belief that this representation accurately maps past reality is a blind, non-evident judgment. Hence, empirical claims grounded purely in historical or personal recollection can achieve only varying degrees of empirical probability, never absolute certainty.

Second, Brentano maintained an unapologetic methodological fallibilism regarding external physical perception. The colors, sounds, spatial forms, and tactile sensations we perceive through our sensory organs do not exist in the external physical world precisely as they appear to us. As natural science itself proves, physical reality consists of unperceived atomic configurations, wave motions, and electromagnetic forces. The naive realism of everyday life is epistemically unjustified; physical phenomena are signs or symbols of an underlying reality, not literal replicas.

Finally, Brentano addressed the classical problem of induction. Rejecting Immanuel Kant’s doctrine of synthetic a priori judgments and pure forms of sensible intuition, Brentano maintained an empirical realism. Inductive inferences—generalizing from observed instances to universal physical laws—are necessary for the progress of natural science, but they remain fundamentally hypothetical. They yield high degrees of practical probability, but they can never attain the absolute, apodictic evidence reserved for pure logic, mathematics, and descriptive psychognosy.

8. Axiology, Moral Philosophy, and the Foundation of Ethics

8.1 The Origin of Our Knowledge of Right and Wrong (1889)

In 1889, Brentano delivered a lecture before the Vienna Law Society titled Vom Ursprung sittlicher Erkenntnis (The Origin of Our Knowledge of Right and Wrong), a work that remains one of the modern classics of moral philosophy and axiology. The text sought to overcome the twin perils that had paralyzed nineteenth-century ethical thought: on the one hand, arbitrary ethical subjectivism and cultural relativism (which reduced morality to mere social convention, historical accident, or personal taste); and on the other hand, the empty, abstract formalism of Kant’s categorical imperative.

Brentano’s breakthrough was the application of his psychological taxonomy directly to the moral realm. If ethics is to have an objective foundation, moral truths cannot be deduced from pure abstract logic, nor can they be derived from theological dogmas that lack empirical evidence. Rather, ethical knowledge must originate in immediate, affective experience.

Drawing upon the structural parallel between judgment and emotion, Brentano asked: How do we know that anything is true? We know it because it can be judged with evident correctness. In the exact same manner, we know that something is intrinsically good because it is worthy of being loved with an intrinsically correct emotion:

“We call a thing good when the love relating to it is correct. In the broadest sense of the word, the good is that which is worthy of love, that which can be loved with a love that is correct.”

Moral value is not an arbitrary invention of society, nor is it a mysterious, non-natural metaphysical entity floating in a Platonic realm. It is an objective property defined by the normative alignment between an intentional act of love (or hate) and its object.

8.2 The Concept of Correct Emotion (Richtiges Lieben)

To defend this ethical theory against charges of subjectivism, Brentano had to explain how an emotion could be deemed “correct” (richtig) without appealing to an external, non-emotional standard. His answer was the profound concept of intrinsically correct emotion (richtiges Lieben).

Just as there are two ways of judging—blind judgments driven by prejudice, and evident judgments characterized by unmistakable rational insight—there are two ways of feeling love or hate:

• Arbitrary or instinctive emotions: A person may have an instinctive craving for poison, or an irrational hatred of a harmless stranger. These affective responses are psychological facts, but they carry no internal warrant of correctness; they are blind emotional compulsions.
• Evident, correct emotions: In contrast, certain affective responses are accompanied by an immediate, unmistakable awareness of their intrinsic correctness. When we experience joy in the contemplation of truth, or love for an act of selfless virtue, or grief over suffering and cruelty, we experience our affective response as being fundamentally appropriate and harmonious with the nature of the object. We recognize immediately that anyone who rejoiced in ignorance or delighted in gratuitous cruelty would be suffering from a fundamentally perverse, incorrect emotional orientation.

This allowed Brentano to formulate a concrete hierarchy of intrinsic values. Goods are not all equal, and moral choices frequently involve conflicts between competing values. Here, Brentano introduced the concept of preferring (Vorziehen). Just as we can immediately perceive that an evident judgment is true, we can experience an evident, correct preference for higher goods over lower goods: knowledge and wisdom are intrinsically superior to mere sensual pleasure; noble character is superior to worldly wealth; the preservation of justice is superior to convenience. Moral objectivity is thus firmly rooted in the transparent, phenomenological evidence of affective preference.

8.3 Practical Ethics and the Utilitarian Synthesis

While Brentano’s foundational meta-ethics was deeply phenomenological and axiological, his practical normative ethics culminated in a sophisticated, universalistic utilitarian synthesis. Once the hierarchy of intrinsic values has been established through evident affective preferences, the central question of normative conduct becomes: What ought I to do?

Brentano formulated the supreme practical moral imperative as the duty to promote the greatest achievable good across the entirety of conscious existence. Every moral agent is obligated to act in such a manner that the totality of intrinsic values—such as wisdom, virtue, beauty, joy, and peace—is maximized, while intrinsic evils—such as pain, ignorance, injustice, and malice—are minimized. Crucially, Brentano’s utilitarianism was an ideal utilitarianism, not a hedonistic utilitarianism like that of Jeremy Bentham. Value is not measured merely in units of subjective bodily pleasure; rather, the highest goods are cognitive, aesthetic, and moral perfections.

This formulation exerted a profound historical influence on twentieth-century Anglo-American analytic philosophy. The British philosopher G.E. Moore read Brentano’s Origin of Our Knowledge of Right and Wrong in its English translation in 1903. In his monumental Principia Ethica (1903), Moore explicitly praised Brentano’s axiological realism, noting that Brentano was the only philosopher who had clearly articulated that the good is a unique, non-natural, objective quality known through immediate intuition, and that practical ethics demands the maximization of ideal goods throughout the universe.

Furthermore, Brentano stressed that practical ethics requires moral education, the cultivation of self-mastery, and the intentional development of virtuous habits. Because human actions ripple outwards into complex social webs, the ethical agent must unite affective sensitivity with rigorous rational foresight, calculating the probable long-range consequences of actions to genuinely serve the common good of humanity.

9. Reism and the Late Ontological System

9.1 The Reistic Turn (Ontological Nominalism)

In the final two decades of his life—a period spent largely in retirement in Florence and later Zurich due to advancing blindness—Brentano executed a radical, uncompromising overhaul of his metaphysical system. This profound intellectual shift, which occupied his thought from approximately 1904 until his death in 1917, is known in philosophical literature as The Reistic Turn or Reism (from the Latin res, meaning “thing”).

In his early 1874 period, Brentano had tolerated a relatively generous ontology, accepting that intentional acts could refer to contents, abstract concepts, immanent objects, and states of affairs. However, in his late philosophy, Brentano was seized by an unrelenting nominalist rigor. Reism asserts a single, absolute ontological thesis: Only concrete, individual things (res, Dinge) exist.

Everything that exists in reality is an individual, concrete entity:

• There are no abstract entities;
• There are no universals (such as “redness,” “humanity,” or “triangularity”);
• There are no independent propositions, meanings, or states of affairs (Sachverhalte);
• There are no real relations floating between things;
• There are no non-existent objects, immanent contents, or Meinongian shadows.

Brentano anchored this radical nominalism in a groundbreaking semantic analysis of language. He divided linguistic vocabulary into two categories:

• Autosemantic terms: Words that refer directly to real, concrete things (e.g., “this man,” “this dog,” “this specific stone,” “this soul”). Only autosemantic terms pick out genuine constituents of the universe.
• Synsemantic terms: Words that appear to name abstract entities or relations, but in reality possess meaning only when used in combination with autosemantic terms (e.g., “redness,” “existence,” “possibility,” “similarity”).

Brentano argued that centuries of philosophical error had been caused by the disastrous hypostatization of synsemantic terms—the naive grammatical delusion of treating linguistic fictions as though they were real metaphysical entities.

9.2 Elimination of Irrealia and Entia Rationis

Having established the reistic thesis, Brentano undertook the systematic ontological demolition of irrealia (non-real entities) and entia rationis (beings of reason). This demanded a radical reformulation of his own classic theory of intentionality.

Opponents argued: If I imagine a centaur, or think of the concept of justice, or mourn the death of Socrates, must not the “centaur,” “justice,” or the “pastness of Socrates” exist as intentional objects? Brentano answered with an emphatic negative. In intentional consciousness, there is no mysterious non-existent object standing in relation to the mind. Rather, intentionality is reconceptualized as a property of a mentally active individual (der Denkende):

• When I think of a horse, there are not two things: “my mind” and an “immanent horse.” There is only one concrete thing: a person thinking of a horse (ein Ross-Vorstellender).
• When I think of a non-existent entity, such as a unicorn, I am not connected to an “unreal object”; rather, I, a concrete human being, am modified into the state of being a unicorn-thinker.

To purge ontology of abstract entities, Brentano devised ingenious methods of paraphrastic reduction, directly anticipating the logical techniques later perfected by Bertrand Russell and Willard Van Orman Quine. Sentences that appear to quantify over abstract entities are translated into sentences mentioning only concrete things:

Within this late reistic framework, the human mind is definitively understood not as a collection of floating mental acts, but as a concrete, indivisible mental substance—a soul that thinks, feels, and wills.

9.3 Time-Consciousness and the Theory of Proteraesthesis

Simultaneously with his late reistic ontology, Brentano developed a revolutionary phenomenological analysis of internal time-consciousness. The central puzzle of temporal experience, which had confounded philosophers since Saint Augustine, can be stated simply: All sensation occurs in the razor-thin slice of the immediate present (the “now”). How, then, can we directly perceive temporal extension, succession, and duration, such as a musical melody?

If we perceived only the instantaneous sound occurring right now, we would hear a succession of isolated atomic notes, but never a melody. If, on the other hand, the preceding notes remained lingering in consciousness as identical present sounds, we would hear a catastrophic cacophony of simultaneous tones sounding at once.

In his early lectures, Brentano attempted to solve this through the theory of original association (ursprüngliche Assoziation), arguing that the mind automatically produces a continuous temporal fringe associating the present sensation with fading past representations. However, in his late philosophy, recognizing the reistic demand for concrete precision, Brentano introduced the concept of proteraesthesis (from the Greek proteros, meaning “earlier,” and aisthesis, meaning “perception”).

According to the doctrine of proteraesthesis, an act of perception does not merely capture an instantaneous present object; it undergoes an intrinsic, continuous, and lawful temporal modification. As a musical note sounds, the initial perceptual presentation continuously transforms into a series of modified representations that present the sound as having just occurred (with the temporal mode of “pastness”). This modification is not an act of memory; it is an inherent, structural dimension of perception itself.

This theory directly inspired and provoked Edmund Husserl. In his 1905 lecture course published as On the Phenomenology of the Consciousness of Internal Time (1928), Husserl took Brentano’s model as his indispensable starting point. While Husserl famously criticized Brentano for treating temporal modifications too psychologically rather than transcendentally, he incorporated Brentano’s structural insight into his own canonical triad of primal impression, retention, and protention, establishing time-consciousness as the foundational stratum of modern phenomenological inquiry.

10. Brentano’s Philosophy of Religion and Natural Theology

10.1 Rational Theology and the Existence of God

Despite his dramatic and public rupture with the institutional hierarchy of the Roman Catholic Church in 1873, Franz Brentano never abandoned his deep, personal Christian theism, nor did he slide into nineteenth-century agnosticism or materialism. On the contrary, he remained committed to a rigorous program of rational natural theology. In his monumental lecture courses, posthumously collected and published as Vom Dasein Gottes (On the Existence of God), Brentano maintained that the existence of a transcendent, personal, and supremely intelligent Creator could be conclusively established through pure human reason, entirely independent of ecclesiastical authority or miraculous revelation.

Brentano approached the question of God with the same empirical and inductive methods he demanded in psychology. He systematically reformulated classical metaphysical proofs, placing immense weight upon a modernized teleological argument (the argument from design). Surveying the panoramic discoveries of nineteenth-century astronomy, chemistry, and biology, Brentano argued that the cosmos exhibits an astonishing, mathematically ordered lawfulness and an intricate fine-tuning of natural conditions essential for the emergence of life and conscious minds.

Crucially, Brentano engaged directly with the rising paradigm of Darwinian evolution. While accepting biological descent and physical transformation as historical facts, Brentano mounted a fierce philosophical challenge against the claim that Charles Darwin’s mechanism of random mutation and natural selection could serve as an exhaustive, ultimate explanation for biological teleology. Brentano argued that random, blind mechanical interactions operating without guiding direction would mathematically result in chaos rather than the stable, highly complex, harmonious organic systems observed in nature. For Brentano, natural selection merely accounted for the negative elimination of the unviable; it could never account for the positive, orderly, and continuous genesis of functional complexity, which fundamentally required a guiding cosmic intelligence.

Alongside his teleological arguments, Brentano reformulated the cosmological and modal arguments, maintaining that the contingent, perpetually changing physical universe cannot contain the ground of its own existence within itself. Through a rigorous analysis of causality, Brentano concluded that the chain of moving, contingent things necessarily terminates in a self-subsistent, necessary, and uniquely active First Cause (causa prima)—an infinite Mind that sustains the universe in being at every moment.

10.2 The Problem of Evil and Theodicy

The central stumbling block for any rational theism is the perennial problem of evil: If God is infinitely powerful, wise, and good, why is the world saturated with physical suffering, disease, catastrophic destruction, and moral depravity? Brentano wrestled deeply with this dilemma, formulating a sophisticated, highly original theodicy that mirrored his axiological theory of correct emotion.

Brentano rejected easy metaphysical dismissals of evil that sought to define it merely as a “privation of the good” (privatio boni). Suffering and moral wickedness are real, agonizing facts of experience. Instead, Brentano constructed an aesthetic and organic defense grounded in the mereological relations between parts and wholes:

• In an artistic masterpiece, such as a great musical symphony or a dramatic tragedy, individual discords, dark shadows, or moments of intense grief are not defects in the composition; rather, they are necessary aesthetic contrasts that elevate the grandeur, depth, and beauty of the entire work to a level of sublime perfection that could never be attained in a state of uniform, monotonous harmony.
• Similarly, within the immense canvas of the cosmos, physical suffering and moral trials provide the indispensable conditions for the emergence of the highest forms of moral virtue: courageous endurance, self-sacrificing love, deep compassion, and moral redemption. A world without suffering would be a world devoid of heroism, profound empathy, and spiritual greatness.

Furthermore, Brentano’s theodicy was marked by an unwavering cosmic optimism. He believed that the universe is not static, but is dynamically ascending along a grand teleological trajectory toward ever greater realization of consciousness, spiritual insight, and goodness. Consistent with this moral optimism, Brentano forcefully rejected the orthodox theological dogma of eternal damnation. He argued that the doctrine of an eternal hell of unending torment is an intellectual and moral monstrosity, fundamentally incompatible with the infinite wisdom and loving nature of God. Divine punishment must be restorative, educative, and finite, ensuring that all conscious souls are ultimately reconciled within the cosmic order.

10.3 The Immortality of the Soul

A natural and necessary culmination of Brentano’s philosophical anthropology was his rigorous defense of the immortality of the individual soul. In an era dominated by biological reductionism, where Ernst Haeckel and Ludwig Büchner proclaimed that mental life was merely a temporary secretion of the physical brain, Brentano defended the persistence of human consciousness after bodily death on strictly analytical and metaphysical grounds.

Brentano’s argument rested upon the absolute simplicity and indivisibility of the mental substance revealed through descriptive psychology:

• Physical objects are spatial aggregates; they are composed of separable parts, and physical death is nothing other than the mechanical dissolution, fragmentation, and scattering of these composite material elements.
• In contrast, as demonstrated by the unity of inner consciousness, the human soul is not an aggregate of spatial pieces. It is an unextended, simple, indivisible unity. When I think a thought or make a judgment, the act is executed by a single, undivided subject, not by fragmented clusters of neurons operating independently.

Because the soul lacks spatial parts, it cannot experience mechanical decomposition, decay, or fragmentation. It is naturally incorruptible. While physical death destroys the bodily instruments through which sensory impressions are gathered, the substantial core of the soul—its capacity for intellectual cognition, spiritual love, and conscious persistence—survives physical dissolution. Brentano viewed physical life as merely the embryonic phase of human existence, with death serving as a liberation into a higher, purely intellectual and affective reality.

11. The Brentano School and the Birth of Phenomenology

11.1 Edmund Husserl and the Development of Phenomenology

The historical significance of Franz Brentano is profoundly magnified by the extraordinary achievements of his students. Foremost among these was Edmund Husserl, universally recognized as the father of modern phenomenology. Husserl, who initially trained as a mathematician under Karl Weierstrass, arrived in Vienna in 1884. Persuaded by his friend Thomas Masaryk (later the first president of Czechoslovakia) to attend Brentano’s lectures, Husserl experienced a profound intellectual conversion. Captivated by Brentano’s vision of philosophy as a rigorous, scientific enterprise, Husserl abandoned mathematics to dedicate his life entirely to philosophy.

Husserl’s early masterpiece, the Logische Untersuchungen (Logical Investigations, 1900–1901), was conceived in direct dialogue with Brentano’s thought. From Brentano, Husserl adopted the foundational insight that intentionality is the defining structural property of consciousness. Husserl took Brentano’s descriptive psychology, deepened its mereological analysis, and transformed it into a descriptive methodology for mapping the correlation between conscious acts (noesis) and the objective correlates given through them (noema).

However, Husserl gradually departed from what he diagnosed as the residual “psychologism” and naturalistic assumptions in Brentano’s thought. While Brentano viewed intentionality as an empirical characteristic of real psychological minds residing in a physical world, Husserl concluded that this approach could never establish the absolute, apodictic foundation required for logic and epistemology. To secure an unshakeable foundation, Husserl formulated the transcendental phenomenological reduction (epoche)—the systematic bracketing of the existence of the natural physical world in order to investigate the pure, transcendental ego and the essential structures of meaning (Wesensschau). Brentano, committed to empirical realism and late reism, viewed Husserl’s transcendental turn with deep dismay, dismissing it as a catastrophic relapse into post-Kantian German Idealism. Despite this tragic theoretical estrangement, Husserl never ceased to revere Brentano, famously stating that without Brentano’s inspiring pedagogical guidance and foundational concepts, phenomenology could never have been born.

11.2 Alexius Meinong and the Graz School of Object Theory

While Husserl pushed Brentano’s intentionality in a transcendental direction, another of his preeminent students, Alexius Meinong, pursued its ontological implications to radical, breathtaking extremes at the University of Graz, establishing the renowned Graz School.

Meinong seized upon the fundamental puzzle that Brentano had introduced: the problem of directedness toward non-existent objects. Meinong argued that traditional Western ontology had been infected with a fatal “prejudice in favor of the real”—an assumption that philosophy should concern itself only with things that exist. In his foundational 1904 work, Untersuchungen zur Gegenstandstheorie und Psychologie (Investigations in Theory of Objects and Psychology), Meinong declared that intentionality proves that the object of thought is completely independent of its existence.

Meinong constructed an immense, panoramic taxonomy of objects that transcends the boundaries of existence:

• Existing objects (Existenz): Concrete physical things, actual mental states, and temporal realities (e.g., horses, rocks, trees);
• Subsisting objects (Bestand): Ideal, timeless entities that do not exist in space-time, such as mathematical numbers, geometric relations, and states of affairs;
• Non-subsisting objects (Aussersein): Objects that possess neither existence nor subsistence, yet remain genuine intentional targets:
  • Fictional and contingent non-existents (e.g., the golden mountain, Pegasus);
  • Logically impossible objects (e.g., the round square, an iron wood-cutting board that is simultaneously wooden and not wooden).

Meinong declared that “there are objects of which it is true that there are no such objects.” Brentano was profoundly alarmed by Meinong’s Gegenstandstheorie (Theory of Objects). Having embarked upon his own reistic turn, Brentano engaged in fierce polemics against Meinong, accusing him of ontological madness and linguistic reification. Meinong’s theory subsequently triggered Bertrand Russell’s famous critique and the development of the theory of definite descriptions in his landmark 1905 paper “On Denoting.” Nevertheless, Meinong’s Graz School made pioneering contributions to early experimental psychology, value theory, and Gestalt research.

11.3 Other Influential Disciples: Stumpf, Marty, Twardowski, and Freud

The sheer caliber and diversity of the thinkers who emerged directly from Brentano’s pedagogical circle is virtually unmatched in the history of modern Western thought:

Carl Stumpf (1848–1936), one of Brentano’s earliest and most loyal disciples, became a titan of German experimental psychology and epistemology. Holding chairs at Munich, Prague, and Berlin, Stumpf pioneered experimental aesthetics and the psychology of sound. At the University of Berlin, he founded the Institute of Psychology, serving as the doctoral mentor for Max Wertheimer, Kurt Koffka, and Wolfgang Köhler—the founding triumvirate of Gestalt psychology. Stumpf’s experimental rigor realized Brentano’s dream of uniting psychological description with empirical natural science.

Anton Marty (1847–1914), who joined Brentano in renouncing the priesthood in the 1870s, served as Professor of Philosophy at Prague. Marty became the preeminent linguistic philosopher of the Brentano School, producing monumental works on the philosophy of language, grammar, semantics, and communication. Marty was the most ardent and sophisticated defender of Brentano’s late reism, engaging in ferocious theoretical debates with Husserl and Meinong over the ontological status of propositions and intentional contents.

Kazimierz Twardowski (1866–1938) completed a brilliant dissertation under Brentano in 1894 titled Zur Lehre vom Inhalt und Gegenstand der Vorstellungen (On the Doctrine of the Content and Object of Presentations). In this text, Twardowski resolved the ambiguity in Brentano’s early intentionality by establishing an absolute, clear conceptual distinction between the mental act, the ideal content (the meaning through which the act refers), and the transcendent object (the target itself). Appointed to the University of Lwów, Twardowski transplanted Brentanian rigor, clarity, and anti-speculative methodology into Poland, founding the legendary Lwów-Warsaw School of Logic, which produced mathematical and logical giants such as Jan Łukasiewicz, Stanisław Leśniewski, and Alfred Tarski.

Finally, among the medical students who flocked to Brentano’s Vienna lectures between 1874 and 1876 was a young Sigmund Freud. Freud took five elective courses under Brentano—the only non-medical philosophy courses he attended during his university training. Under Brentano’s supervision, Freud even translated an essay by John Stuart Mill into German. While Freud would later achieve global fame through his postulate of the dynamic unconscious—a concept Brentano vehemently rejected—scholars have increasingly recognized the deep, subterranean echoes of Brentano’s thought in Freud’s system: the insistence on active psychic drives, the act-like character of mental defense mechanisms, and the foundational act of mental representation.

12. Historical Legacy and Contemporary Relevance in Cognitive Science and Philosophy of Mind

12.1 The Intentionality Debate in Analytic Philosophy

In the mid-twentieth century, when Anglo-American philosophy was largely dominated by logical positivism and Skinnerian behaviorism, the thought of Franz Brentano experienced an unexpected and earth-shaking renaissance through the work of the American philosopher Roderick Chisholm. In his pathbreaking 1957 book Perceiving: A Philosophical Study, Chisholm reintroduced Brentano’s Thesis to the analytic world, igniting what is known as the Intentionality Debate.

Chisholm reformulated Brentano’s thesis from a psychological doctrine into a rigorous linguistic criterion of intentionality. He demonstrated that sentences used to describe mental states exhibit logical peculiarities that render them utterly irreducible to the extensional language of physical science. Specifically, intentional sentences exhibit:

• Referential opacity (failure of existential generalization): In normal physical discourse, if the statement “John kicks the ball” is true, it logically follows that there exists a ball that John kicks. However, in intentional discourse, the statement “John hopes for a benevolent extraterrestrial” can be entirely true even if no extraterrestrial exists.
• Failure of substitutivity of co-referential terms: If “Mark Twain” is identical to “Samuel Clemens,” then in physical contexts, the truth of “The rock struck Mark Twain” guarantees the truth of “The rock struck Samuel Clemens.” But in intentional contexts, the statement “George believes Mark Twain wrote Tom Sawyer” does not entail that “George believes Samuel Clemens wrote Tom Sawyer,” because George may not know the author’s real name.

Armed with Brentano’s Thesis, analytic philosophers mobilized against physicalism, behaviorism, and identity theory. If intentional states cannot be described or translated into extensional, physical vocabulary, then the mental cannot be reduced to physical brain matter. This forced twentieth-century cognitive science and contemporary analytic philosophy of mind—spearheaded by figures like Daniel Dennett, Jerry Fodor, Fred Dretske, and John Searle—into extensive research programs aimed at either “naturalizing” intentionality (explaining how brain matter can represent things) or defending the irreducibility of intentional consciousness.

12.2 Higher-Order Theories of Consciousness

In contemporary philosophy of mind and cognitive neuroscience, Brentano’s analysis of inner consciousness has re-emerged as one of the most vibrant and hotly debated models of phenomenal awareness. Modern theorists frequently grapple with the question: What makes a mental state a conscious mental state rather than a non-conscious neurophysiological event?

Contemporary responses have divided broadly into two camps, both of which trace their lineage directly back to Brentano’s insights:

1. Higher-Order Theories (HOT): Philosophers such as David Rosenthal have proposed that a mental state is conscious when it is the intentional target of an accompanying, higher-order thought or perception. While HOT theorists often cite Brentano as an early inspiration, their model requires two distinct mental states: a first-order mental state (e.g., an itch) and a distinct second-order mental thought directed at the itch.

2. Self-Representational (Same-Order) Theories of Consciousness: To avoid the lethal infinite regress and artificial fragmentation inherent in higher-order models, contemporary philosophers like Uriah Kriegel, Kenneth Williford, and Dan Zahavi have revived Brentano’s original, authentic doctrine under the banner of Self-Representationalism (or “Brentanian Same-Order Theory”). As Brentano originally argued, a conscious mental act does not require an external, higher-order thought to become conscious; rather, consciousness is an intrinsic, reflexively self-intimating feature of the mental act itself. In a single, undivided cognitive event, the act represents its primary object while simultaneously self-representing its own occurrence.

This Brentanian model has found profound resonances in modern cognitive neuroscience and phenomenological neuropsychology. In studies of perceptual reporting, subjective agency, and the neural correlates of consciousness (NCC), researchers increasingly utilize Brentano’s distinction between pre-reflective, reflexive self-awareness (inner perception) and effortful, introspective attention (inner observation), confirming that human consciousness operates as an integrated, self-luminous whole.

12.3 Overall Assessment of Brentano’s Place in Intellectual History

To assess the legacy of Franz Brentano is to recognize him as one of the ultimate intellectual architects of contemporary philosophy. Standing at the great continental divide of nineteenth-century European thought, Brentano served as the grand bridge uniting traditions that are too often viewed as utterly irreconcilable:

• He rescued the terminological clarity, ontological seriousness, and realism of classical Greek and medieval Scholasticism, re-infusing them into modern academic discourse;
• He absorbed the methodological rigor, empirical discipline, and fallibilism of British empiricism and modern natural science;
• He decisively fathered the Continental Phenomenological Tradition through Edmund Husserl, which flowed outward into Martin Heidegger, Maurice Merleau-Ponty, Jean-Paul Sartre, and Emmanuel Levinas;
• He laid the structural and logical foundations for Central European Analytic Philosophy through Twardowski and the Lwów-Warsaw School, and through Chisholm, Moore, and Russell.

Brentano’s philosophical architecture represents an inspiring vision of what philosophy can achieve: a discipline that does not shy away from the ultimate metaphysical questions of existence, God, morality, and the human soul, yet pursues those questions with the humble, methodical, and inductive precision of a rigorous natural science. In his lifelong insistence that consciousness is intentionally directed, internally unified, and normatively oriented toward truth and the good, Franz Brentano constructed a philosophical edifice that continues to illuminate and challenge the frontiers of human thought.

Conclusion

Franz Brentano died in Zurich on March 17, 1917, blind and physically frail, in the midst of the catastrophic inferno of the First World War—a conflict that obliterated the cosmopolitan Austro-Hungarian Empire he had so long enriched. Yet, more than a century after his death, his intellectual presence remains exceptionally vital. Across the spectrum of modern philosophy of mind, cognitive science, metaphysics, and axiology, the problems that consume contemporary research are unmistakably the problems Brentano articulated with such pioneering clarity.

From the ongoing struggle to understand how consciousness relates to its intentional objects, to the mereological analysis of part-whole structures, to the debate over self-representational theories of phenomenal awareness, philosophy continues to speak in accents forged by Brentano. By demonstrating that conscious experience possesses its own irreducible, lawful, and evident structural reality, Brentano ensured that the study of the subjective mind could never be reduced to a mechanical footnote of physical nature. He stands eternally as an intellectual giant who taught philosophy how to observe the mind with scientific rigor while honoring the profound depths of human experience.

References

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