Aquinas's Synthesis of Aristotelianism and Christianity

Thomas Aquinas: A 13th-Century Scholar

Historical and Sociocultural Context

Saint Thomas Aquinas lived during the 13th century, a period marked by Europe's resurgence, with the growth of towns, trade, and the rise of universities. Feudalism remained the dominant social structure, but the emergence of the bourgeoisie signaled a shift in power dynamics.

This era witnessed the pursuit of a universal Christendom, influenced by cultural exchanges between Islam and Christianity, spurred by the Crusades and the Toledo School of Translators. The introduction of Aristotle's works to the West significantly impacted philosophical thought, shaping the development of scholasticism.

Influences and Impact

Aquinas was deeply influenced by Aristotle, incorporating aspects of his ontology, anthropology, epistemology, ethics, and poetics. Augustinian Platonism also played a role, particularly concerning the immortal soul and degrees of perfection, where Aristotelian philosophy clashed with Christian doctrine.

Aquinas drew upon earlier philosophers like Avicenna and Maimonides. His distinction between essence and existence originates from Avicenna, while the concept of natural law connects to Stoic philosophy. He also engaged with biblical texts and Averroes' thought, rejecting the latter's doctrine of double truth.

Aquinas's influence is evident in the Spanish Scholasticism of the 16th and 17th centuries. His concept of natural law significantly shaped the Catholic Church's official doctrine. However, modern philosophers like Descartes and Kant critiqued his ideas, and his philosophy was sometimes viewed as hindering scientific progress.

Aquinas's Thought

Reason and Faith

Aquinas argued for a single truth accessible through reason and faith. Reason derives knowledge from sensory data, while faith relies on divine revelation. These two paths are independent. The truths of faith, exceeding human reason's grasp, are studied by theology and accepted as divinely ordained.

Truths of reason, belonging to philosophy, are demonstrable through human intellect. Some truths, demonstrable by reason, are also revealed by God, merging faith and reason (e.g., immortality and creation). Theology can employ reason to understand truth (natural theology). Philosophy serves theology, and since truth is singular, philosophy and reason must align with faith.

Five Ways to Prove God's Existence

Aquinas offered five ways to demonstrate God's existence, all sharing a common structure:

1. Starting from an observation of experience.
2. Applying the principle of causality.
3. Rejecting an infinite regress of causes.
4. Concluding with a first, uncaused being—God.

The five ways are:

1. Motion: From observed motion to an unmoved mover.
2. Efficient causality: From subordinate causes to a first, uncaused cause.
3. Contingency: From contingent beings to a necessary being.
4. Degrees of perfection: From degrees of perfection to an infinitely perfect being.
5. Cosmic order: From the order of the world to a first, ordering intelligence.

Essence and Existence

To address creation, Aquinas distinguished between essence (the nature or possibility of a being) and existence (its actuality). In God, essence and existence are identical; his nature necessitates existence. Other beings are contingent; their essence doesn't entail existence, which they receive through God's creative act.

Anthropology

Aquinas affirmed the immateriality of the intellect and soul. In humans, the intellect is linked to a material body, a substantial union of body and soul based on Aristotle's hylomorphism. Human understanding, tied to a body with senses, begins with sensory knowledge. The intellect develops concepts from perceptual data.

The challenge is how we move from individual perceptions to universal concepts. Aquinas proposed that the intellect abstracts, universalizing particular sensory experiences. This abstraction operates on 'phantasms'—memory traces of perceptions—stripping them of individuality to form universal concepts.

Ethics

Aquinas's ethics are theocentric. Our actions aim towards ultimate happiness, achieved through exercising the rational soul (knowledge and virtue). God is the supreme good, and knowing God is humanity's highest aspiration. A life devoted to seeking God is the most perfect and happy.

God's eternal law establishes order in the universe. Humans, unlike other beings governed by inescapable physical laws, possess free will. Natural law, the part of eternal law specific to humans, respects this freedom. It comprises moral principles based on human nature.

Humans can understand their inclinations and deduce rules of conduct. These inclinations include self-preservation, procreation, and the pursuit of truth and social life. Positive law, regulating social interaction, must be compatible with human nature and aim for the common good.