Central Problem

The central problem of Thomistic philosophy is the systematic harmonization of Aristotelian philosophy with Christian revelation, specifically addressing the relationship between faith and reason (fides et ratio). While previous thinkers either subordinated philosophy to theology or maintained their incompatibility, Tommaso seeks to establish their legitimate autonomy and fruitful collaboration within a unified vision of truth.

The problem manifests in several dimensions: metaphysically, how can the Aristotelian conception of necessary, eternal forms be reconciled with the Christian doctrine of creation ex nihilo? Epistemologically, what is the proper scope of rational inquiry concerning divine truths, and where must faith supplement reason? Anthropologically, how can the Aristotelian conception of soul as form of the body be compatible with personal immortality and resurrection? Ethically, how do natural virtue and divine grace relate in achieving human flourishing and salvation?

Aquinas inherits from Alberto Magno the project of incorporating Aristotle into Christian thought, but realizes that mere piecemeal adaptation is insufficient. A radical reformation of the entire philosophical-theological system is required, one that neither reduces faith to reason (as the Averroists tended) nor abandons reason for authority (as anti-dialecticians urged).

Main Thesis

Tommaso establishes a comprehensive synthesis centered on the distinction between essence (essentia) and existence (esse or actus essendi), which constitutes the reforming principle allowing Aristotelianism to express Christian doctrines. His main theses include:

The Harmony of Faith and Reason: Reason and faith cannot contradict each other because both derive from God. Reason can: (1) demonstrate the “preambles of faith” (e.g., God’s existence); (2) clarify revealed truths through analogies; (3) refute objections against faith. Faith serves as the rule for correct reasoning, but does not annul reason’s autonomous domain.

The Metaphysics of Participation: In creatures, essence and existence are really distinct; existence is the act (actus essendi) by which essences, having being only potentially, actually exist. Only in God do essence and existence coincide—God is Being itself (ipsum esse subsistens). All finite beings receive their existence by participation in divine Being, establishing the metaphysical necessity of creation.

The Five Ways: God’s existence, though self-evident in itself, requires a posteriori demonstration for humans. The five ways proceed from motion, efficient causality, contingency, degrees of perfection, and finality, each concluding to a transcendent cause: the unmoved mover, first cause, necessary being, perfect being, and intelligent orderer.

Analogical Predication: Terms applied to both God and creatures are neither univocal (identical) nor equivocal (entirely different), but analogical—partially similar and partially dissimilar. This safeguards divine transcendence while permitting meaningful theological discourse.

The Transcendentals: Being (ens) possesses universal properties that transcend the categories: unum (unity), verum (truth), bonum (goodness). Every being, insofar as it exists, is true (conformable to divine intellect) and good (desirable). This grounds Thomistic ontological optimism.

Natural Law Theory: There are four types of law: eternal law (God’s rational governance of the universe), natural law (human participation in eternal law through reason), human law (particular applications of natural law), and divine positive law (revealed law directing humans to supernatural ends).

Historical Context

Tommaso (1225/26-1274) lived during the great flowering of Scholasticism when Aristotelian texts, transmitted through Arabic translations and commentaries, had revolutionized European universities. The full Aristotelian corpus—including the Physics, Metaphysics, and De Anima—arrived in Latin translation during the 12th-13th centuries, presenting both opportunity and crisis for Christian thought.

The Aristotelian worldview appeared to conflict with fundamental Christian doctrines: the eternity and necessity of the world contradicted creation; the identification of soul with bodily form seemed to preclude immortality; the thesis of a single universal intellect (as interpreted by Averroè) eliminated individual immortality. The faculty of arts at Paris witnessed the rise of Latin Averroism under Sigieri di Brabante, teaching positions apparently incompatible with faith.

Ecclesiastical authorities responded with condemnations (1210, 1215, 1270, 1277), prohibiting the teaching of Aristotle’s natural philosophy. Meanwhile, the Franciscan school, led by Bonaventura, defended the Augustinian-Platonic tradition against Aristotelian innovations, advocating divine illumination and the primacy of will over intellect.

Into this contested terrain came Tommaso, a Dominican friar trained under Alberto Magno at Paris and Cologne. His project—continued throughout teaching positions at Paris, Rome, and Naples—was to demonstrate that authentic Aristotelianism, properly understood and reformed, could serve as the rational foundation for Christian theology. His two great Summae (the Summa contra Gentiles and the unfinished Summa Theologiae) represent the most comprehensive medieval synthesis of philosophy and theology.

Philosophical Lineage

flowchart TD
    Aristotele --> Avicenna
    Aristotele --> Averroè
    Aristotele --> Alberto-Magno
    Platone --> Agostino
    Agostino --> Bonaventura
    Agostino --> Tommaso
    Avicenna --> Tommaso
    Alberto-Magno --> Tommaso
    Pseudo-Dionigi --> Tommaso
    Boezio --> Tommaso
    Tommaso --> Duns-Scoto
    Tommaso --> Ockham
    Tommaso --> Neotomismo
    
    class Aristotele,Avicenna,Averroè,Alberto-Magno,Platone,Agostino,Bonaventura,Tommaso,Pseudo-Dionigi,Boezio,Duns-Scoto,Ockham,Neotomismo internal-link;

Key Thinkers

ThinkerDatesMovementMain WorkCore Concept
Tommaso1225-1274ThomismSumma TheologiaeEssence-existence distinction
Alberto Magno1193-1280AristotelianismCommentaries on AristotlePhilosophy-theology distinction
Bonaventura1221-1274AugustinianismItinerarium mentis in DeumDivine illumination
Avicenna980-1037Islamic PhilosophyBook of HealingNecessary being
Averroè1126-1198AristotelianismCommentaries on AristotleUnity of intellect
Sigieri di Brabante1240-1284AverroismDe anima intellectivaDouble truth

Key Concepts

ConceptDefinitionRelated to
Essence (essentia)The quiddity or nature of a thing; what a thing is; responds to quid est?Tommaso, Metaphysics
Existence (esse, actus essendi)The act by which essences actually exist; the actuality of all actsTommaso, Metaphysics
ParticipationThe act by which creatures “take part” in being, receiving partially what belongs to God totallyTommaso, Neoplatonism
Analogy of beingNeither univocal nor equivocal predication; terms apply to God and creatures with partial similarityTommaso, Metaphysics
TranscendentalsProperties belonging to every being as such: unity, truth, goodnessTommaso, Metaphysics
Five waysFive a posteriori proofs of God’s existence from motion, causality, contingency, perfection, finalityTommaso, Philosophy-of-Religion
AbstractionProcess by which intellect extracts universal forms from individual matterTommaso, Epistemology
AdaequatioTruth as correspondence of intellect and thing (adaequatio intellectus et rei)Tommaso, Epistemology
Natural lawHuman participation in eternal law through reason; the rational creature’s share in providenceTommaso, Ethics
Agere sequitur esse”Action follows being”—ontological foundation of ethics; mode of action follows mode of beingTommaso, Ethics

Authors Comparison

ThemeTommasoBonaventuraAverroè
Faith and reasonHarmony; distinct but cooperativeFaith illuminates reasonPhilosophy autonomous from religion
Knowledge of GodVia negativa, causality, eminenceDivine illuminationPhilosophical demonstration
Soul-body relationSoul as form, yet subsistentSoul as substance + formSoul separated from individual
IntellectIndividual active intellect in each soulRequires divine illuminationSingle universal intellect
Eternity of worldNeither demonstrable nor refutableDemonstrably falseDemonstrably true
Metaphysical frameworkReformed AristotelianismAugustinian NeoplatonismPure Aristotelianism
Greek philosophyAristotle as “the Philosopher”Plato preferredAristotle as “the Philosopher”

Influences & Connections

Summary Formulas

  • Tommaso: Essence and existence are really distinct in creatures but identical in God; all finite being participates in divine Being; faith and reason harmoniously cooperate, each in its proper domain.
  • Alberto Magno: Philosophy must proceed by demonstration alone, distinct from theology which proceeds from revealed principles; Aristotle represents the perfection of human reason.
  • Bonaventura: The mind’s journey to God requires divine illumination at every stage; natural reason is insufficient without the light of faith; the soul is a spiritual substance, not merely form.
  • Averroè: The world is eternal and necessary; the intellect (both agent and possible) is one for all humanity; philosophy expresses demonstratively what religion teaches symbolically.

Timeline

YearEvent
1225/26Tommaso born at Roccasecca near Cassino
1243Enters the Dominican Order at Naples
1245-1252Studies under Alberto Magno at Paris and Cologne
1254-1256Writes De ente et essentia at Paris
1256-1259First Parisian regency as Master of Theology
1259-1264Writes Summa contra Gentiles in Italy
1265Begins Summa Theologiae
1269-1272Second Parisian regency; writes against Averroists
1270Bishop Tempier condemns 13 Averroist propositions at Paris
1274Tommaso dies at Fossanova on way to Council of Lyons
1277Bishop Tempier condemns 219 propositions, including some Thomistic ones
1323Tommaso canonized by Pope John XXII
1879Leo XIII’s encyclical Aeterni Patris establishes Thomism as official Catholic philosophy

Notable Quotes

“Grace does not destroy nature, but perfects it.” — Tommaso

“Being is the actuality of all acts and the perfection of all perfections.” — Tommaso

“Truth is the adequation of thing and intellect.” — Tommaso, citing Isaac Ben Israeli


NOTE

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