First, a few points on the overall structure of this work: there are 3 parts to the Summa and each part of the Summa is broken up by questions, and each question has a number of articles. Each article consists of a few objections followed by Aquinas' general response to the question and a particular adversus to each raised objection. When I cite the Summa, it be in the format of part number, question number, and article number (ex. "Ia.3.6").
Unfortunately, every question and article in the Summa is more than worthy material--this makes the choice tough. Today, I will focus on Question 2 article 3: Whether God Exists?
Any student in philosophy has heard of "Aquinas' 5 Ways" for the existence of God, but not every student actually reads the primary source. It is rather incredible to think that these proofs for the existence of God--which are very famous--are RIGHT HERE IN QUESTION 2 of the Summa!
The first way is often called "the first Mover" argument and it goes as follows:
- In the world, things are in motion; whatever is in motion is put in motion by another.
- Motion is nothing but the "reduction of something from potentiality to actuality" (Ia.2.3); nothing can be moved in this way except by something already in act.
- A fire that is actually hot makes wood, which is potentially hot, to be actually hot--thereby moving and changing it to a state of "actually being hot". Furthermore, that which is actually hot cannot also, at the same time, be potentially hot. Therefore it is impossible that the same thing be both mover and moved in the same respect, and we know that whatever is in motion is put into motion by another.
- There cannot be an infinite chain of movers because then there would be no first mover, and, consequently, there would be no other movers. Subsequent movers move insofar as they were put into motion by the first mover.
- Therefore a first mover exists and was moved by no other; this first mover we call God.
The second way is related to the mover argument, but instead focuses on efficient causality:
- We find that the world is full of efficient causes.
- These efficient causes cannot be causes of themselves, since it would require them to be prior to themselves, which is impossible.
- Efficient causes follow from order, and it is therefore impossible to go on to infinity: the first cause is the cause of the intermediate cause (which may be many), and the intermediate is that of the ultimate cause. Take away the first cause, and you take away all its effects.
- We know that intermediate and ultimate causes exist. Therefore a first cause must exist.
- This first efficient cause we call God.
The third way is that of the nature of necessity and contingency:
- We find things in nature that are possible to be and likewise possible not to be.
- Something which is possible to not be must, at some time, not be; therefore if everything is possible to not be, then at some time, nothing existed. But if this were true, and nothing existed at some time, then nothing could ever come to exist since we know that things come to exist by things already existing.
- Therefore, not all beings are merely possible, but there must exist some whose existence is necessary and therefore not possible to not exist.
- A truly necessary being must exist without being dependent upon another for existence; this necessary being we call God.
The fourth way is an argument from "gradation":
- We see things all around us that are "good", "true", and "hot" and other such predicates; some are "more or less-ly" predicated in different things, but they all resemble some maximum.
- Now, "the maximum of any genus is the cause of all in that genus" (Ia.2.3).
- Therefore, there must be something which is, to all beings, the cause of goodness, truth, heat, etc. and every other perfection--we call this being God.
The fifth and final way is often misunderstood; it is the argument from design:
- We see things in nature that lack intelligence, yet act in such as way as to exhibit design. Things act towards some end almost without fail.
- Whatever lacks intelligence cannot move towards that end without being directed by some intelligence as "the arrow is shot to its mark by the archer" (Ia.2.3).
- Some intelligent being exists as the source of all of nature's directedness and we call this being God.
Let this all soak in...
I said that the design argument is often misunderstood for a reason. William Paley has an argument that he thinks is similar: suppose you stumble upon a watch on a beach and you had never seen a watch before; even suppose that the watch is broken and does not tell time--would you not still suspect that this watch is different in kind from a stone on the beach? The watch seems to be ordered or directed towards some end, and we see this in the little parts that all come together to serve a unified and intelligible purpose. Paley suggests that this is like the universe: we see design in the form of parts working together as wholes to serve some end, and while there are imperfections in the design, it is designed nonetheless.
Here is my issue with this: Aquinas is talking about internal/intrinsic final causality. Paley's watch example is completely different. A watch is not designed in the same way that an acorn is: the watch is artificial and has been artificially given a purpose. The acorn and the "design" Aquinas is speaking of does not require a watchmaker, but rather he is emphasizing the fact that things in nature that lack intelligence are nonetheless directed towards the same types of respective ends almost without fail, and the things themselves can achieve those ends on their own: the acorn can become an oak due to its very nature.
Much more on this later. Cheers.
