Aquinas' Five Ways

Second Way

Argument from Efficient Cause

Contents

Outline


Explanation


Objections


Sources

Argument from Efficient Cause: Outline

Everything has a cause, i.e, an efficient cause. Your parents are the efficient cause of a sibling of yours, an acorn is the efficient cause of a tree that grows from it. Aquinas observes the existence of efficient causes in nature and then considers the implications of a sequence of causal events.


  • We perceive that all things have an efficient cause
  • Nothing exists prior to itself
  • Therefore, nothing is the efficient cause of itself
  • If the cause doesn't exist, neither does the effect
  • Therefore, if the first thing in a sequence of things does not exist, neither does the sequence itself
  • If the sequence of efficient causes were to infinitely regress, nothing would currently exist
  • Because things currently exist, the sequence of efficient causes cannot infinitely regress
  • Therefore, there must be a first efficient cause, and we call that first uncaused causer God


Argument from Efficient Cause: Explained

Simlar to the argument from motion, Aquinas starts his argument by observing that everything has an efficient cause. Given that nothing exists prior to itself, it's absurd to conclude that something could be the cause of itself. Therefore, if something is to be caused, it must be caused by something else. Likewise, to take away the cause is also to take away the effect. Aquinas argues that an infinitely regressive causal sequence has no beginning and is thus subject to the previous premise. Because an infinite regression has no beginning, no effect can come from it. However, given that things do in fact exist, it's necessary to conclude that there must be someone or something that acts as the first efficient cause.


Objections

Is the Unmmoved Mover the Uncaused Causer?

Let us assume for a moment that both the argument from motion and the argument from efficient cause are both valid. The first establishes an unmmoved mover while the second establishes an uncaused causer. Why should we assume that these two entities are the same? No logical connection exists between the two, and Aquinas makes no effort to link the two. Instead, he assumes that they're the same being. In fact, the five ways as a whole can be seen as proving five different entities rather than a single God. This objection, therefore, extends to all the other parts of Aquinas' five ways as well.


Fallacy of Composition

Causalty may exist within the universe, but what reason is there to believe that the universe itself has a cause? In other words, causalty may be a property that occurs within the universe, but there's no reason to believe that such a concept should extend to the universe as a whole.


Circular Model of the Universe

The sequence of causes in the universe doesn't necessarily need to be linear. It's entirely possible that the sequence of causes in the universe instead circles back on itself. In this scenario, no first cause exists, and yet everything still has a cause. Likewise, an infinite causal chain may not have a first cause, but this doesn't mean the sequence as a whole is devoid of effect. In an infinite regress, no cause is being removed. Therefore, no effect is being removed either.


Problems of Being the First Cause

If God is a perfect cause, we're forced to conclude that the effects stemming from God are also perfect because if God were truly perfect, what reason does he have for creating the imperfect? If this point is refuted, one is forced to admit that the universe as a whole is imperfect. If this point is accepted, then God is as finite as the universe is finite because each cause is proportioned to its effect.


This argument can be refuted in a number of ways. It may be true that causes are proportional to their effects, but it's also possible for the effect to be less than the cause. The effect cannot be greater than its cause, but it may be lesser. Therefore, a perfect being could create imperfections. Given that we are far from ever understanding what a perfect being might think, we have no reason to conclude that a perfect being doesn't have reason to create imperfections.