The work of Thomas Aquinas known as "Summa Theologica" or "The Five Ways" is often cited as proof of God's existence. One should ask, if these five proofs are actually proofs, how could they be denied? The fact of the matter is they are not proofs, the five "ways" include a great deal of fallacy, however eloquent and poetic they are stated.

 

For those interested, a translation of “The Five Ways” can be found here:

 

http://www.newadvent.org/summa/1002.htm#3

 

To summarize, the five proofs are as follows:

 

1. Argument from motion:

            a. Some things are in motion

            b. All things in motion were put into motion by another

            c. Nothing can be the cause of its own movement

            d. We cannot have an infinite regression of movers

            e. There must be a first mover

            f. The first mover is God

 

2. Argument from causality

            a. There is cause and effect

            b. Nothing can cause itself

            c. We cannot have an infinite regression of causes

            e. There must be a first cause

            f. The first cause is God

 

3. Argument from existence

            a. Some things exist, some do not.

            b. Things that exist must have obtained their existence from a prior thing

            c. We cannot have an infinite regression of prior existing things

            d. There must be a thing that necessarily exists first, to cause to exist all other things

            e. This thing is God

 

4. Argument from perfection

            a. Things have varying degrees of attributes, such as goodness, or nobility

            b. That things can be "more" or "less" those attributes (more good, more noble) implies that there exists a maximal quantity of that attribute (most good, most noble) and that there exists a thing that embodies that maximal quantity.

            c. The thing that is maximal in an attribute is the cause of all others that contain that attribute (The hottest thing is the cause of all other hot things)

            d. In regards to goodness, there must be a thing that is maximally good.

            e. This maximally good thing is God

 

5. Argument from intent

            a. All things act toward an end

            b. Things cannot act toward an end without guiding intelligence

            c. There must exist an intelligent being that guides the acts of natural things

            d. This being is God

 

Now, 1, 2, and 3 are essentially the same argument. Perhaps in Aquinas' time motion, causality and existence were viewed distinctly, but with today’s knowledge we can view them all as cause and effect issues. Things can be caused to be put in motion; things can be caused to come into existence, etc. Thus #2 covers 1 and 3.

 

The first issue, and it is a glaring one, is that of induction. 1, 2, 3 and 5 are all arguments of induction. Induction is where you take a specific set of examples and then generalize a conclusion. The problem with this is that the conclusion is not necessarily true, based on the premises. To put it another way, a conclusion derived from induction is not proof of anything.

 

Before I continue, I feel compelled to mention that similar objections have brought against the scientific method. I find it truly hypocritical that a person would deny the validity of science based on the problem of induction yet hold the above arguments to be true. The scientific method, rather, uses abduction to derive the most likely explanation of a given set of observations. At no point does science say that such explanations are conclusive. There is nothing in science that is concluded, it is always open-ended. I'd be interested in understanding how a person can criticize science for using inductive/abductive reasoning when science does not claim its answers are necessarily true but at the same time feels the induction used by Thomas Aquinas produces conclusions that are necessarily true, when it is impossible for inductive reasoning to produce such conclusions.

 

1, 2, 3 and 5 are all inductive arguments. Aquinas as taken a set of observations (observed causes have preceding cause, including motion and existence; things acting toward a specific end have a guiding intelligence) and has derived generalized conclusions (All causes must have preceding causes, including motion and existence; all things acting toward an end have a guiding intelligence).

 

For 1, 2 and 3, Aquinas draws out the conclusion to a logical contradiction: there cannot be an infinite regression of causes/motion/existences. Under normal circumstances, this would be it; Aquinas as essentially disproved his own argument via reductio ad absurdum. But instead of recognizing this, he proposes a solution by defying his initial premises! To explain away the potential infinite regression of causes, he proposes the existence of a "first cause" and "uncaused caused" despite the fact that this violates his premise that all things must have a cause. He offers no reason why this "first cause" is an exception to the general rule he has established. He simply labels it God. Now, there really is no issue with this label, however it does set things up for more fallacious reasoning down the road, which I will address.

 

Way #5, however, does not contradict itself and remains consistent. Yet it is still fallacious, even when ignoring the problem of induction. It is fallacious because it begs the question. Aquinas has said that all things moving toward an end must be guided by intelligence. And since things other than humans are not intelligent, they cannot be guiding themselves toward and end and must get this guidance from elsewhere. This may be from humans, as an arrow shot by an archer guided to a target or from something else. For all things not driven by human intelligence he says is driven by God. This is begging the question because it assumes that all things are being driven to not only an end, but in such a way as to achieve "the best result". Aquinas offers no reason or support why we must assume that all things are acting toward a specific end and are acting in such a way as to achieve a "best result". It very well could be that things are simply acting to no end and, thus, are guided by no intelligence at all.

 

Way #4 is a bit trickier in that it muddles a bunch of different concepts. Aquinas has said that we find in objects varying degrees of certain attributes, and that there *must* be a maximum to that attribute. If one thing can be hotter than another, then there exists a hottest object. What Aquinas muddles here is that there does exist maximum values for certain attributes, such as heat. There is an absolute zero and there is a theoretical maximum temperature, there is a maximum velocity and a minimum velocity. But this does not mean all attributes have a maximum nor does it necessarily mean that there are objects that possess this maximum value for that attribute. There are numbers greater and lesser than another, yet no greatest or smallest number. The qualities he tries to apply this to are goodness, nobility, perfection, etc. These are abstract concepts that are not tied to physical values. This means they are more like numbers than they are like temperature and velocity. There is no reason for us to believe that there are maximal values for any of those. Even if there did exist entities that contained an attribute to its maximum quantity, there is no reason to say that there can be only one. He falsely proposes fire as the hottest object and the cause of all others, yet he doesn't propose that only one fire exists. So even if there is a maximal goodness or maximal nobleness, why must they all rest in a single object?

 

Now we come to the label issue. Aquinas’ arguments propose that certain entities must exist and that these entities are all God. This is a clear-cut case of equivocation. Even if we give Aquinas the benefit of the doubt, he has offered no reason why the entity called God as a result of the first three arguments is the same as the entity Called god as a result of the fourth argument or is the same as the entity called God as a result of the fifth argument. Simply giving them the same name doesn't make them the same entity. And, furthermore, he does not link any of these depictions of God to the Christian God he was attempting to prove. Just because he proves there was a creator doesn't mean he proves that creator was the same God that gave his son to save humanity. If you want to prove the existence of an entity, you have to prove each and every attribute that entity is alleged to have.

 

To summarize, Aquinas' conclusions are not conclusive at all, as they rely on textbook examples of induction. The contradictions that arise from his first three arguments should demolish those arguments yet they don't and instead Aquinas' proposes a solution which only further contradicts the premises he laid out to begin with. His fourth and fifth arguments make unfounded assumptions regarding, respectively, the nature of attributes and the ends toward which things act. To round it all out, the arguments taken together equivocate the nature of God. Aquinas simply relies on the reader to assume that each "proven" entity is one and the same, and furthermore represents the Christian God, without providing support.