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Aquinas, Hume and Kant on the Cosmological Argument for God’s Existence


Arguments for the existence of God can be sources of fascination for experienced philosophers and those new to philosophy alike. If it were possible to prove the existence of God through logic alone, this would settle a core pillar underlying human religious practices. In this article, we’ll outline one argument that has played a prominent role in philosophy: the cosmological argument. And we’ll consider the influential objections offered by Hume and Kant.

Aquinas and the Cosmological Argument

Thomas Aquinas was a 13th-century Dominican friar and theologian. The Cosmological Argument for the existence of God was presented in his “Summa Theologica.” The Cosmological Argument is rooted in the idea that everything in the universe is contingent and requires a cause or explanation for its existence. Aquinas posited that this chain of causation cannot go back infinitely and must ultimately lead to a necessary being, which is to be identified as God.

Aquinas provided the argument from motion, the argument from causation, and the argument from contingency.

  1. The Argument from Motion asserts that everything in motion must have been set in motion by something else. Aquinas observed that nothing can move itself, meaning that the motion we observe in the world is the result of a series of movers. However, this sequence cannot proceed infinitely, as an infinite regress of movers would imply no initial movement. Thus, there must be an Unmoved Mover who initiates all motion without itself being moved, and Aquinas identifies this being as God.
  2. The Argument from Causation is based on the principle that every effect has a cause. Within the world, we observe a chain of causation where each cause is itself the effect of a previous cause. Like the Argument from Motion, the chain of causes cannot extend backward infinitely because, without a first cause, there would be no subsequent causes and, therefore, no effects. Aquinas concluded that a First Cause must exist, and this uncaused cause is God.
  3. The Argument from Contingency starts with the observation that things in the universe come into and go out of existence, indicating that their existence is not necessary. If everything were contingent, then conceivably there could have been a time when nothing existed. However, if this were the case, nothing would exist now, as something cannot arise from nothing. Therefore, there must be at least one necessary being whose existence is not contingent on anything else. This necessary being, who imparts existence to all contingent beings, is what Aquinas refers to as God.

Aquinas’s approach was heavily influenced by Aristotle’s metaphysics, specifically his concepts of potentiality and actuality, and the necessity of a Prime Mover or Uncaused Cause. Although there have been various interpretations and expansions on Aquinas’s argument by subsequent philosophers and theologians, the core remains the assertion of God as the necessary foundation and cause of all that exists.

Aquinas’s Cosmological Argument attempts to bridge empirical observation with theological inference. By leveraging observable phenomena like motion and causation, Aquinas provides a rational basis for theism that does not rely solely on divine revelation but seeks to engage reason and experience. His argument continues to be a central topic in philosophical discussions on the existence of God, offering a framework where faith and reason can coexist in a coherent and supportive manner.

David Hume’s Objections to the Cosmological Argument

David Hume, an 18th-century Scottish philosopher, critiqued the Cosmological Argument.

  1. Hume challenges the principle of causality upon which the Cosmological Argument relies. He argues that the human mind naturally seeks explanations, but this inclination does not imply that every event must have a cause. Hume claims that causality is a habit of thought rather than an absolute necessity. Hume questions whether it is even coherent to conceive of a being whose non-existence is impossible, suggesting that any such assertion exceeds the limits of human understanding.
  2. Hume critiques the leap from the existence of the universe to the existence of a single, divine cause. He points out that just because every individual component within the universe has a cause, it does not follow that the entire universe requires a singular external cause. He likens this to the fallacy of composition, arguing that just because every element within a collection has a property, it does not mean the entire collection shares that property. For example, if each brick in a wall is small, it does not necessarily mean the wall itself is small. Thus, Hume suggests it is an unfounded assumption to conclude that the universe itself must have a distinct cause based on the causality observed within it.
  3. Hume interrogates the necessity of exclusively attributing the cause of the universe to a divine being. Even if he were to concede that the universe has a cause, Hume argues that this cause need not resemble the God described by religious traditions. It could be multiple causes, impersonal, or even chaotic forces rather than the orderly, omniscient deity posited by the Cosmological Argument. This critique underscores his broader philosophical stance, questioning humanity’s capacity to comprehend the nature or identity of any ultimate cause.
  4. Hume emphasizes the problem of infinite regress, which the Cosmological Argument is attempting to solve by asserting a first cause. He argues that proposing a first cause does not necessarily resolve this issue—it merely pushes the question one step back. If God is posited as the first cause, one might still ask what caused God. The Cosmological Argument, therefore, might fail to terminate the series of causes in a satisfying or logically consistent manner.

By questioning the necessity and nature of a first cause, Hume opens up a broader inquiry into the limitations of human reason when it comes to metaphysical claims about the universe’s origins.

Immanuel Kant’s View on the Cosmological Argument

Immanuel Kant’s objections to the Cosmological Argument for the existence of God are a pivotal part of his critique on traditional metaphysical arguments.

  1. Kant critiques the reliance on the principle of sufficient reason, which asserts that everything must have a reason or cause. He argues that the jump from contingent and finite existence to an absolute necessary being is not logically justified. According to Kant, the concept of necessity cannot extend beyond the realm of logical necessities to factual states of existence. When cosmologists propose that the world requires an external, necessary cause, they inadvertently step beyond our possible experience and the empirical use of reason.
  2. Kant disputes the idea of an unconditioned necessity that the Cosmological Argument posits. He points out that our knowledge is limited to the realm of experience. Since the condition for a conditioned series can only be known within the context of human experience, postulating a transcendent cause that lies outside empirical understanding is speculative and unwarranted. This means that one cannot escape from the chain of conditions to a first, unconditioned cause without empirical evidence, which transcends human understanding.
  3. Kant holds that the leap from the existence of a necessary being to the characteristics often attributed to God is unfounded. Even if we were to concede that a necessary being exists, nothing about this necessity specifies that the being must possess qualities such as omnipotence, omniscience, or moral goodness. According to Kant, these attributes are erroneously incorporated without any empirical basis to support them within the framework of the Cosmological Argument.

Kant’s objection ultimately centers around the limitations of human reason and cognition. He believes that rational inquiry into the realms beyond possible experience, such as the existence of God, leads to antinomies—contradictory, yet reasonable propositions. By navigating beyond empirical evidence, philosophical inquiry assumes a role akin to speculative metaphysics, which Kant criticizes for its groundless abstractions. The conformity of human reason is confined, according to Kant, to the sensible world, and thus, speculating outside its bounds leads to misrepresentations and unsupported assertions.

Conclusion

The Cosmological Argument, while ingenious, is not ultimately persuasive. Hume and Kant helped us to see its fundamental flaws. If a philosopher hopes to prove God’s existence through logical argument, they will need to look beyond the Cosmological Argument and attempt to find a more plausible alternative.

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