Thomas Aquinas: Philosophy, Theology, and Influence

Posted on Nov 17, 2024 in Philosophy and ethics

Thomas Aquinas: Life and Work

Thomas Aquinas is a central figure in scholastic philosophy and theology. His most renowned works include Summa Contra Gentiles and Summa Theologiae. Aquinas’s writings encompass various philosophical genres prevalent during his time:

  • Commentaries: Interpretations and critiques of existing texts.
  • Disputations: Polemical writings addressing criticisms and refuting opposing viewpoints.
  • Summae: Comprehensive summaries of doctrine.

Latin Averroism

Adapting Aristotle’s philosophy to Christian doctrine presented greater challenges than Plato’s. Two key Aristotelian theories clashed with Christian beliefs:

  • Eternity of the World: Aristotle posited an eternal world without beginning or end, contradicting the Christian doctrine of creation.
  • Mortality of the Individual Soul: Aristotle viewed the soul as the life principle of the body, ceasing to exist upon the body’s death.

The conflict between faith and reason persisted. Latin Averroists attempted to resolve this through the theory of double truth.

The Theory of Double Truth

This theory proposes two distinct truths: a truth of faith (e.g., the world is created) and a truth of reason (e.g., the world is eternal). Both are considered true, but within separate realms and for different purposes. Thomas Aquinas rejected this theory, arguing that faith and reason are distinct sources of knowledge with different content. He categorized truths as follows:

  • Articles of Faith: Truths revealed by God, incomprehensible to human reason.
  • Preambles of Faith: Truths revealed by God but also demonstrable through reason.
  • Rational Truths: Truths concerning the natural world, not divinely revealed, accessible to reason.

Aquinas maintained that in cases of conflict, reason, not divinely revealed faith, is fallible, thus subordinating reason to faith.

The Aristotelianism of Thomas Aquinas

Aquinas integrated Aristotelian concepts into Christian theology. Key aspects include:

Concerning Reality and Nature

  • Theory of Motion
  • Hylomorphic Theory
  • Distinction between Substance and Accidents
  • Theory of the Four Causes: Material, Formal, Efficient, and Final

Concerning Theology

  • Demonstration of God’s Existence Based on Motion
  • Conception of God as Pure Act

Concerning Anthropology

  • Man as a Substantial Union of Body and Soul

Concerning Ethics

  • The Ultimate End of Man is Happiness

Evidence of the Existence of God

Aquinas addressed two key questions regarding God’s existence:

1. Need for Demonstration

He distinguished between truths self-evident in themselves and for us, and truths self-evident in themselves but not for us.

2. Possibility of Demonstration

He differentiated between a priori and a posteriori demonstrations. Aquinas developed his famous “Five Ways” to demonstrate God’s existence, each following a similar structure:

  1. Observation of an empirical fact.
  2. Application of the principle of causality.
  3. Assertion of the impossibility of an infinite regress of causes.
  4. Conclusion of God as the First Cause.

The Five Ways are based on:

  1. Cosmology
  2. Causality
  3. Contingency
  4. Degrees of Perfection
  5. Teleology (Governance of Things)

Thomistic Epistemology

Aquinas’s epistemology emphasizes knowledge of universal essences. He distinguishes three types of universals:

  • Ante rem (Ideas in the Divine Mind)
  • In re (Forms of Things)
  • Post rem (Concepts in the Human Mind)

The process of knowledge involves:

  1. Perception
  2. Abstraction
  3. Actualization
  4. Individualization

Thomistic Anthropology

The soul is the form and act of the body. Aquinas identifies three operations of the soul:

  • Vegetative: Nutrition and growth.
  • Sensitive: Motor function and sensation.
  • Rational: Intellect and will.

Ethics and Politics

Aquinas’s ethics are teleological. He distinguishes between:

  1. Natural Law: The ultimate end of man is beatitude (supernatural happiness). Natural law includes the inclinations to self-preservation, procreation, and the pursuit of truth and social life.
  2. Positive (Human) Law: An extension of natural law, never contradicting it.
  3. Eternal Law: God’s governance of nature.
  4. Divine Law: Revealed law, such as the Ten Commandments.