Written by Jason Petersen
Introduction to the Argument for God from Motion
Thomas Aquinas formulated this argument, and it is an a posteriori argument.(This means that the argument is derived from experience.) The support given for this argument will focus on the cosmos.
The argument’s premises are as follows:
P1. There are objects that are in motion.
P2. If an object is in motion, then its motion must be caused by something outside of itself.
P3. There cannot be an infinite regression of movers.
P4. So, there must be an unmoved mover who set everything in motion.
Conclusion: The unmoved mover must be God.
Justification for Premise One:
We can observe from experience that objects are in motion. The best way to demonstrate this(for the purpose of this argument) is by considering motion in outer space. Our universe is expanding, but what caused this expansion to take place? Certainly, the expansion of the cosmos entails motion. Aquinas defined motion as “change.” It is important to note that these changes do not have to be physical. For instance, one could argue that thoughts entail change. This article will be focusing on the motion of the cosmos to support Aquinas’ argument.
Justification for Premise Two:
Any heavenly body in outer space is not capable of causing its own motion. Its motion must be caused by something else, such as gravity, the expansion of the universe, or being hit by another moving object. Heavenly bodies move according to a cause-effect relationship with other heavenly bodies with the universe. To understand this, we must look at causation.
In the following sequence of events, let A be the initial expansion of the universe(event A), and all subsequent events(B, C, and beyond) be objects that were set in motion by A. If A causes B, and B causes C, then what caused A? Event A can’t cause itself, because A would have to preexist its own cause. C also can’t cause A, because that would mean that A had a role in its own cause, for if C caused A, then A indirectly caused itself before A occurred. Therefore, whatever caused event A to occur must be outside of A.
Further, if we were to consider that A was the initial expansion of our universe, then what could cause A if the event A can’t precede itself? The cause for event A must be caused by something independent of event A. The cause must be an efficient cause. An efficient cause is an agent that can stop and start change. For any other type of cause or event A would come with a plethora of problems. For instance, let’s consider a vacuum to be the cause of the initial expansion of the universe. The vacuum is not able to stop and start change freely. Rather, it would always cause change(an infinite regress), or it would never cause change without external interference to make the vacuum unstable. If the vacuum is not unstable, then it won’t produce matter. If a vacuum is stable, then matter will not be produced, as there would be a balance of matter and antimatter.
Justification for Premise Three:
The notion of an infinite regress of causes for motion is a metaphysical absurdity, because the notion of an actual infinity typically ends up giving self-contradictory answers to questions. For instance, infinity minus infinity would still be equal to infinity. A couple illustrations can be given to support this point:
1.) Suppose that a hotel has an infinite number of rooms. All of the odd-numbered rooms have been rented out. How many rooms would be left? The answer is infinity. So, infinity minus infinity equals infinity.
2.) Suppose that a hotel with an infinite number of rooms; however, this time all of the rooms are rented out except for six rooms. How many rooms would be left? The answer is six. Therefore, this time, infinity minus infinity equals six.
Certainly, an actual infinity lends itself to self-contradictory propositions when questions concerning the nature of the actual number surface. Because of the self-contradictory of nature an infinite regress within the physical world, there can not be an infinite series of past events.
Justification for Premise Four:
If the cause for the universe being set into motion must be independent of the event that set the universe into motion, then what kind of cause should it be? We already established that a natural cause, such as a vacuum would either produce change for eternity because it is unstable for eternity, or it would be stable for eternity, and would, therefore, never produce any change. If the vacuum would never produce any sort of change, then no motion would occur. And event A(the initial expansion of the universe) would never occur no matter how much time is given.
If we can’t have an infinite series of events causing change(motion), and given that the initial expansion of the universe cannot cause itself, then the cause must be external. Not only must this cause be external to the universe, but it would have to be an efficient cause that can start and stop change. This would avoid the problems caused by the notion of an infinite number of past events or the inability for any change to occur. Therefore, the cause must be an unmoved mover that can start and stop change.
Justification for the Conclusion:
Our conclusion is arrived at deductively. The unmoved mover can only be God, for a quantum vacuum or any other natural cause can not satisfy the criteria of an efficient cause.
Limitations of the Argument
Certainly, this argument does not argue specifically for the Christian God. Rather, it argues for a God that is the “unmoved mover.” This argument also relies heavily on empiricism and experience. Unfortunately, universal conclusions may not be arrived from experience, and knowledge cannot be produced by experience either. The argument is also heavily reliant on empirical observations from the scientific method, but science is unable to produce epistemic knowledge. Thus, the argument can be nothing more than opinion and does not lead to epistemic knowledge of the God of Christianity. If science, experience, and sense perception cannot lead to knowledge, then this argument cannot produce epistemic knowledge of God. As scripture teaches, God is the one who reveals the truth of scripture and the Gospel to us.(Matthew 15:16).
Be that as it may, the argument is still interesting for purposes of discussion of Christians. It may also be used to show that by the atheist’s empirical standards, they would have to accept that atheism is false, for if the empirical standard could lead to a knowledge of a god, then atheism would be false, for atheism cannot be true if there is a god. Since this argument is limited in what it can accomplish, we must take care to not make the argument the center of our apologetic, rather, the authority of scripture and the Gospel ought to be the center of our apologetic.
Possible Objections(Courtesy of Iron Chariots Wiki):
1. What about the Flying Spaghetti Monster?
Answer: See this article.
2. You haven’t proven that it is your God that set the universe into motion. It could be any god for all you know.
Answer: See this article.
3. Two bodies at rest will start to move towards each other due to gravity. They can be each other’s first mover. Therefore, the prior mover requirement is unnecessary.
Answer: If this is the case, then given an infinite timeline, why is it that these two bodies have not collided with each other already? If the timeline for these two bodies is infinite, then two problems occur:
1.) The bodies would have already collided because they have allegedly starting moving towards each other an infinite number of years ago.
2.) If the bodies were one time at a standstill, then what caused them to start moving in the first place? If their gravity was pulling on each other, what finally go these two bodies moving?
In conclusion, such a phenomenon would not be considered an efficient cause, and therefore, this solution that the atheist provides falls short.
4. Pairs of virtual particles are created (and annihilated) all of the time, out of literally nothing. These particles affect each other’s motion, thus disproving Aquinas’s premise.
Answer: These are not actually particles. Virtual particles are disturbances within a quantum vacuum. Such an explanation for the motion of the heavenly bodies within the universe would amount to an infinite regress, which is a metaphysical absurdity. You can not have an infinite regress of movers in the physical universe. Further, these fluctuations can only occur within a quantum vacuum. Besides, these virtual particles are caused by other particles. Therefore, the virtual particles can not be what set the universe in motion.
5. Even if there is an infinite regress of causes, so what? The human mind is uncomfortable with the concept of infinity, but reality has no obligation to make us comfortable.
Answer: The objection is insinuating that the reality is that infinite regresses are possible. It is up to the atheist to prove this claim while taking the descriptive laws of the universe into account. If metaphysical reasons do not satisfy the atheist, then perhaps the fact that the universe would have already ran out of usable energy with an infinite number of movers in the universe will convince them that this position is not tenable.
6. Who Created God?
Answer: See this Article.
7. What Moved the Unmoved-Mover?
Answer: See this Article.