What are the Five Proofs for the Existence of God of St Thomas Aquinas?
Does God exist?
This is surely a fundamental question that nearly all humans have pondered with throughout human history. The vast array of religions are a testimony to the human tendency to grasp at the divine. This in itself is perhaps the strongest testimony to God’s existence. It can be said that all humans have an innate desire; an emptiness that they feel must be filled. The human quest for power, riches, sensual pleasure, security, fame and indulgence in natural pleasures is a response to the heartfelt desire for a higher goodness. Temporal pleasures and even natural love is often transitory and ultimately unfulfilling. As humans indulge in their passions their desires continue to go unfulfilled. Many attempt to fill the void with increasing worldly pleasures with little results.
Such powerful and elusive desires are a cry from the soul which seeks something that can not be gratified by the things of this world. For the moment we will consider discontent of the heart as a mark of God calling us to embrace him.
But I demand physical proof!
St. Thomas Aquinas proposed five proofs in which humans can use natural reason to prove the existence of God through extrinsic evidence. Through the use of natural reason we can logically conclude in the existence of God. Yet strictly speaking, God’s existence cannot be definitively proven through laboratory tests and experimental science. Not all things are subject to experimental science. It is illogical to say, "If I can not see, taste, touch, feel or hear something it must not exist!" Reason and extrinsic evidence must also be considered. Experimental science and intrinsic evidence cannot definitively prove historical events, and yet by reason we know they have occurred. And surely were science falters and extrinsic evidence fail, reason and intrinsic evidence can prove the spiritual which can not be measured by material sciences.
St. Thomas Aquinas five proofs of the existence of God
I. Aquinas’ first proof is through the argument of motion. It can be noted that some things in the universe are in motion and it follows that whatever is in the state of motion must have been placed in motion by another such act. Motion in itself is nothing less then the reduction of something from the state of potentiality to actuality. Because something can not be in potentiality and actuality simultaneously, it follows that something can not be a mover of itself. A simple example of this is a rubber ball motionless on a flat surface. It has the potential for motion, but is not currently in the state of actual motion. In order for this to happen, something else in motion must set the ball in motion, be that gravity, another moving object or the wind. And yet something must have set that object in motion as well (even gravity, a force caused by matter warping the space-time fabric, attributes its existence to pre-existing matter and the exchange of pre-existing graviton particles). Thus pre-existing motions cause all motions. Yet, this chain can not extend into infinity because that would deny a first mover that set all else in motion. Without a first mover, nothing could be set in motion. Thus we acknowledge the first and primary mover as God.
II. The second proof follows closely with the first and expounds the principle of causality. St. Thomas explains that in the world of sense there is an order of causes and effects. There is a cause for all things such as the existence of a clock. And nothing can cause itself into existence. A clock cannot will itself into existence, it must be created and caused into existence by something else. A clockmaker creates a clock and causes its existence, and yet the material of the clock and the clockmaker did not cause themselves to exist. Something else must have caused their existence. All things can attribute their existence to a first cause that began all causes and all things. We call this first cause God.
III. Aquinas next explains that things of this universe have a transitory nature in which they are generated and then corrupt over time. Because of this the things of nature can be said to be "possible to be and possible not to be". Since it is impossible for these things always to exist, then it indicates a time when they did not exist. If there are things which are transitory (and are possible not to be) then at one time there could have been nothing in existence. However, as was already explained in his second proof, there must have been a first cause that was not of transitory nature that could have generated the beginning of nature.
IV. In his fourth point Aquinas notes that there is a certain gradation in all things. For instance we can group things that are hot according to varying degrees of the amount of heat perceptible in that object. In classifying objects there is always something which displays the maximum fullness of that characteristic. Thus universal qualities in man such as justice and goodness must attribute their varying qualities to God; the source of maximum and perfect justice and goodness.
V. Finally, Thomas Aquinas says that the order of nature presupposes a higher plan in creation. The laws governing the universe presuppose a universal legislature who authored the order of the universe. We cannot say that chance creates order in the universe. If you drop a cup on the floor it shatters into bits and has become disordered. But if you were to drop bits of the cup, they would not assemble together into a cup. This is an example of the inherent disorder prevalent in the universe when things are left to chance. The existence of order and natural laws presupposes a divine intelligence who authored the universe into being.
Conclusions from St. Thomas Aquinas’ proofs
These proofs reveal many truths about the divine God. The existence of life and the order of creation can be attributed to God; the cause and creator of the universe. From the principal of causality we know that God is infinite and beyond the laws of nature and our human universe. In order for him to be the first cause, he must have been in existence before all else in the universe. We know that nature is composed of things that are not eternal but are transitory. Thus the universe attributes its transitory nature to a first cause that cannot be defined as transitory and is thus not a part of nature. So God is neither of a finite lifetime, nor is he "inseparably a part of nature". Nature by itself is not God. We also know that God is the divine source of justice and goodness; attributes found in all men and woman in varying degrees. In fact our universal feelings of justice demand a God. Justice is not a human attribute created by us, it is a quality imprinted in our very being by our creator. A being who must also posses the very quintessence of justice in order to endow us with justice.
Finally, we know that God is personal. It can be likewise argued that the qualities that make humans personal and conscience are what place us above other created things such as plants and animals. Since God is a higher order of being, he is likewise the very quintessence of a personal being.