Aquinas & the Cosmological Arguments: Crash Course Philosophy #10

This chapter explores the medieval theological and philosophical contributions of Thomas Aquinas, focusing on his first four Cosmological Arguments for the existence of God. Building upon and responding to earlier ontological arguments, Aquinas anchored his reasoning in observation of the natural world, tackling the philosophical problem of infinite regression and evaluating the strengths and critical vulnerabilities of these classic proofs.

1. Historical Context: Anselm vs. Aquinas

Anselm of Canterbury's Ontological Argument: Formulated in the 11th century, Anselm attempted to prove God's existence purely through a priori conceptual analysis (defining God as "that than which nothing greater can be conceived").
Aquinas's Theological Stance: Living roughly two centuries later, the Italian theologian and philosopher Thomas Aquinas believed deeply in God, but found Anselm's ontological proof insufficient.
The Shift to Empirical Observation: As a philosopher, Aquinas felt the burden of proof required robust, rational argumentation grounded in the observable physical world rather than abstract definitions alone.
The Fivefold Strategy: Fearing that a single argument might fail to convince skeptics, Aquinas formulated five distinct proofs for the existence of God. The first four of these are collectively known as the Cosmological Arguments.

2. Understanding Cosmological Arguments

Definition of Cosmological Arguments: Arguments that seek to prove the existence of God by examining fundamental, undeniable empirical facts about the nature of our physical universe.
Empirical Grounding: Despite existing in a pre-scientific era, Aquinas leveraged observations of physical reality—such as motion, cause-and-effect relationships, and contingency—to build his philosophical framework.
The Problem of Infinite Regress: A central logical hurdle across Aquinas's first three arguments is the rejection of an infinite regress (an endless chain where each point depends entirely on a preceding one without any ultimate starting point).
Aquinas's Rejection of Infinity: Aquinas viewed actual infinite regressions in causal chains as logically absurd, asserting that an infinite past implies a sequence of events that either started with nothing or never actually started at all.

3. Argument 1: The Argument from Motion

Empirical Observation: We live in a world where physical objects are actively in motion.
The Chain of Motion: Everything that is in motion is put into motion by something else; nothing moves itself.
Real-Life Analogy (Falling Dominoes): Imagine watching a line of falling blocks. If you claim no one pushed the first block and that they have simply been falling for all eternity, you face the absurdity of an un-started sequence.
The Prime Mover: To avoid an infinite regress of movers, there must be a starting point—an initial entity that initiates motion without being moved itself.
Logical Flow:
- Objects are in motion.
- Everything in motion is put into motion by something else.
- An infinite regress of movers is impossible.
- Therefore, there must be a First Mover (Unmoved Mover), which is God.

4. Argument 2: The Argument from Causation

Structural Similarity: This argument mirrors the Argument from Motion, shifting focus from physical displacement to general cause-and-effect relationships across the universe.
The Rule of Causality: Everything that occurs has a cause; nothing can cause its own existence.
Tracing the Line Backwards: If you trace the chain of causes behind any event (such as watching a video), you travel backward through time. According to Aquinas, this causal chain cannot stretch backward infinitely.
The First Cause: There must be an initiating causal point that was not caused by anything prior.
Logical Flow:
- Things happen and effects are produced in the universe.
- Every effect requires a distinct prior cause (nothing causes itself).
- An infinite regress of causes is impossible.
- Therefore, there must be a First Cause (Uncaused Cause), which is God.

5. Argument 3: The Argument from Contingency (Possibility)

Conceptual Prerequisite: In philosophy, a sharp distinction is made between necessary existence and contingent (possible) existence.
- Contingent Being: An entity that can fail to exist; an entity whose existence is not guaranteed (this includes human beings).
- Necessary Being: An entity that must exist, has always existed, and cannot possibly fail to exist.
Human Contingency: You exist because of a specific biological convergence of sperm and egg, making your existence fundamentally contingent—a matter of chance.
Rejecting Infinite Contingency: Aquinas argued that a universe composed entirely of contingent beings is absurd, because if everything were merely possible/contingent, there could theoretically have been a time when nothing existed at all.
Logical Flow:
- Contingent things exist and can cause other contingent things.
- A universe consisting solely of contingent things implies an infinite regress where, at some point, nothing would exist.
- An infinite regress of purely contingent events is impossible.
- Therefore, there must be at least one Necessary Being required to sustain all contingent existence, which is God.

6. Argument 4: The Argument from Degrees of Perfection

Comparative Metrics: We understand properties and values by measuring them against comparative scales (e.g., hot/cold, good/bad, big/small).
Relativity of Scale: A dog is small compared to an elephant, but massive compared to a mouse. We make these judgments relative to a standard.
The Standard of Perfection: In abstract concepts—such as academic grades (where an 'A' represents the highest mark)—we measure value against a hierarchical ceiling.
Ontological Peak: Aquinas argued that all qualitative properties (truth, goodness, nobility) exist in degrees, which implies the existence of an ultimate, absolute standard of perfection against which all things are measured.
Logical Flow:
- Characteristics and qualities come in varying degrees.
- For something to possess a quality in a certain degree, there must be an ultimate standard of perfection.
- Therefore, there must exist a being that is the absolute pinnacle of perfection, which is God.

7. Critical Evaluation and Philosophical Objections

Once Aquinas's four cosmological arguments are established, critical philosophers (both religious and secular) evaluate their logical integrity. Several major objections undermine these proofs:

Objection Category	Core Critique / Challenge	Implication for Aquinas's Arguments
Identity Gap	The conclusions yield an "Unmoved Mover" or "First Cause," but fail to prove the existence of the specific God of religious tradition (e.g., the God of Abraham, Isaac, and Jacob who answers prayers and feels emotion).	The proofs land far short of establishing a personal deity.
Polytheism Problem	Nothing in the cosmological arguments logically restricts the conclusion to a single deity.	The logic could equally support a committee of gods, an ancient elder with a beard, multiple bearded elders, a stone, or a cosmic egg.
Consciousness Undefined	The arguments do not establish that the First Mover or Necessary Being possesses consciousness, will, or agency.	The resulting entity could be an impersonal, inanimate physical force.
Denial of Infinite Regress	Aquinas insists that infinite regressions are logically impossible, but offers insufficient proof as to why an infinite past or infinite causal chain cannot exist.	If infinite regression is logically permissible, the first two arguments collapse entirely.
Self-Defeating Flaw	If Aquinas insists that everything in motion requires a mover, and every effect requires an outside cause, this rule should logically apply to God as well. Exempting God creates a special pleading fallacy.	If God can exist uncaused or un-moved, other entities (like the universe itself) could potentially share that exemption without needing a creator.

8. Summary of Philosophical Methodology

Accepting Conclusions vs. Rejecting Arguments: A foundational rule in philosophy is that you can theoretically agree with a conclusion while recognizing that the specific argument provided to reach it is logically flawed.
The Burden of Counter-Argumentation: Simply dismissing an argument by saying "you are wrong" is insufficient. A philosopher must construct a rigorous counter-argument detailing where the error occurred and why an alternative line of reasoning is superior.
Engaging the Great Conversation: Historical thinkers like Aquinas set the stage centuries ago, inviting modern thinkers to evaluate, repair, or dismantle their propositions. This active debate over ultimate questions defines the discipline of philosophy.

Summary and Key Takeaways

Empirical Foundation: Thomas Aquinas rejected pure conceptual proofs (like Anselm's ontological argument), choosing instead to ground his theological philosophy in observable facts about the natural world.
The Fivefold Strategy: Aquinas formulated five proofs for God's existence, the first four of which are categorized as Cosmological Arguments.
Argument from Motion: Posits that everything in motion is moved by something else, requiring an initial Unmoved Mover to break infinite regress.
Argument from Causation: Asserts that every effect has a prior cause, necessitating an uncaused First Cause to start the causal chain.
Argument from Contingency: Distinguishes between contingent and necessary beings, arguing that a universe of purely contingent things requires a Necessary Being to prevent absolute non-existence.
Argument from Degrees: Proposes that qualitative values and characteristics are measured against an ultimate standard of absolute perfection, identified as God.
The Identity Deficit: Critics note that Aquinas's arguments fail to prove the existence of a personal, conscious, monotheistic deity who listens to prayers or cares for humanity.
The Special Pleading Vulnerability: If everything requires a cause or mover, exempting God from this rule represents a self-defeating logical inconsistency.
The Impermissibility of Infinite Regress: The validity of Aquinas's early arguments hinges entirely on whether an actual infinite regression of causes or motion is truly impossible—a premise heavily contested by modern philosophers.
The Spirit of Philosophy: Philosophy requires active intellectual engagement, demanding that disagreements be supported by structured counter-arguments rather than bare dismissal.