Aquinas' development of Aristotle's telos

The Acorn:

• An acorn's telos is to grow into an oak tree.
• The acorn is directed by its nature toward this goal.
• When it achieves its telos (becomes an oak), it is fulfilling its nature.

The Eye:

• An eye's telos is to see.
• A good eye is one that sees well (fulfills its purpose).
• A bad eye is one that doesn't see well (fails its purpose).

A Knife:

• A knife's telos is to cut.
• A good knife cuts well; a bad knife doesn't.

1. By Using Reason:

• What distinguishes humans from other animals is our capacity for reason.
• Therefore, the human telos is to live according to reason.

2. By Cultivating Virtue:

• Eudaimonia is achieved through cultivating virtues (excellences of character).
• Virtues include: courage, justice, temperance, wisdom.
• A virtuous person uses reason to find the "golden mean" between extremes.

3. By Living in Community (Polis):

• Humans are social animals who flourish in community.
• The polis (city-state) provides the context for human flourishing.

1. The Concept of Telos:

• Aquinas agreed with Aristotle that everything has a purpose (telos).
• The acorn still has the telos of becoming an oak.
• Humans still have the telos of flourishing (eudaimonia).

2. The Importance of Reason:

• Aquinas agreed that reason is essential to human flourishing.
• Humans can use reason to discover what is good for them.
• This is why Aquinas calls it "Natural Law"—knowable through reason, not just revelation.

3. The Role of Virtue:

• Aquinas agreed that cultivating virtues is essential to achieving our telos.
• He adopted Aristotle's cardinal virtues (prudence, justice, fortitude, temperance).

1. God as the Source of All Telos:

• Aristotle: Telos is built into the nature of things—no personal God required.
• Aquinas: Telos exists because God designed everything with a purpose.
• The Christian God is the efficient cause (creator) of everything.
• God is also the ultimate final cause—the goal toward which all creation tends.

2. God as the Ultimate Human Telos:

• Aristotle: The human telos is eudaimonia achieved through virtue and reason in this life.
• Aquinas: The ultimate human telos is eternal union with God—the Beatific Vision.
• Earthly flourishing is real but incomplete—true happiness comes only in heaven.

3. Telos Reflects God's Omnibenevolent Plan:

• For Aquinas, telos is not just a natural fact—it's part of God's loving design.
• God created everything with a purpose according to His omnibenevolent plan.
• Following your telos means participating in God's plan for creation.

4. The Addition of Theological Virtues:

• Aquinas kept Aristotle's cardinal virtues: prudence, justice, fortitude, temperance.
• But he added the theological virtues: faith, hope, and charity (love).
• These theological virtues are necessary for achieving the ultimate telos (union with God).
• They can only be achieved through God's grace, not human effort alone.

How This Follows from Telos:

1. Everything has a telos (purpose) given by God
2. Good = fulfilling your telos (achieving your purpose)
3. Evil = failing to fulfill your telos (missing your purpose)
4. Therefore: do what fulfills your telos (good) and avoid what doesn't (evil)

Human Nature Has a Telos:

• God designed human nature with specific natural inclinations.
• These inclinations point toward our God-given telos.
• By using reason, we can discover what these inclinations are and what they tell us about how to live.

Strength 1: Empirical Foundation

The Argument:

• Telos-based ethics are grounded in observable reality.
• We can observe that things have natures that incline them toward certain goals.
• An acorn really does grow into an oak; eyes really are for seeing.

Aquinas' Achievement:

Aquinas provides an empirical basis for ethics—morality is discovered through observation of nature, not just revelation.

Strength 2: Universal and Objective

The Argument:

• Because telos is built into nature by God, morality is universal and objective.
• It applies to all humans because all humans share the same nature and telos.
• It's not relative to cultures or individuals—it's absolute.

Strength 3: Harmonizes Faith and Reason

The Achievement:

• Aquinas showed that Greek philosophy and Christian faith are compatible.
• Reason and revelation both lead to the same truths about how to live.
• This gave Christianity a powerful philosophical foundation.

Strength 4: Provides Purpose and Meaning

The Argument:

• Aquinas' framework gives human life objective purpose and meaning.
• We're not random accidents—we're designed by God for a purpose.
• Life has a goal (union with God) that gives direction and significance.

Criticism 1: Modern Science Has Eliminated Telos

The Objection:

• Modern science explains the natural world without telos.
• Aristotle's view: An acorn has the telos of becoming an oak tree.
• Modern science: The acorn's growth is explained by DNA, material structure, and physical forces.

Evolution eliminates purpose:

• Human nature and our behavioral inclinations are explained by evolution.
• We have certain traits because they helped our ancestors survive and reproduce.
• This is material and efficient causation, not final causation (telos).

Implication:

• If telos doesn't exist, Aquinas' entire ethical system collapses.
• Natural Law requires that humans have a God-given purpose—but science suggests we don't.

Response:

• Defenders argue that even if science explains HOW things work, it doesn't explain WHY.
• Material and efficient causes don't eliminate the question of ultimate purpose.
• Science describes mechanisms; it doesn't answer questions of meaning and value.

Criticism 2: Derives "Ought" from "Is" (Naturalistic Fallacy)

The Objection:

• Aquinas moves from descriptive claims about what is natural to prescriptive claims about what we ought to do.

The Problem:

• This is the naturalistic fallacy—you can't derive "ought" from "is".
• Just because something is natural doesn't mean it's morally good.

Response:

• Aquinas would argue that for beings with a God-given nature, what fulfills that nature just is what's good.
• The naturalistic fallacy assumes a separation between facts and values that Aquinas doesn't accept.

Criticism 3: Karl Barth—Reason Is Corrupted by Sin

The Objection:

• Protestant theologian Karl Barth rejected natural theology.
• He argued that human reason is corrupted by original sin.
• We cannot reliably discover God's will through reason alone.
• We need divine revelation (Scripture) to know how to live.

Implication:

• Aquinas places dangerous overreliance on human reason.
• Natural Law may lead us astray because our reasoning is fallen.

Response:

• Aquinas acknowledged that reason is wounded by sin but not destroyed.
• Grace perfects nature; it doesn't replace it.