1. Introduction to Philosophy Lecture 4 Thomas Aquinas & an Intro to Philosophy of Religion
By David Kelsey

2. Aquinas Saint Thomas Aquinas Lived from 1225-1274.
A monk whose writings have been deemed authoritative by the Catholic Church.
In 1244 became a friar. Later he became a priest and in 1323 was made a Saint.
Heavily influenced by the works of Aristotle.
In his work Summa Theologica he gave 5 different argument’s for God’s existence.
He called these the 5 ways.

3. Aquinas on Aristotle Aquinas on Aristotle:
Aquinas was greatly influenced by the works of Aristotle.
But Aquinas thinks there is a fundamental mistake in Aristotle’s metaphysics.
Aquinas thinks Aristotle overlooks the notion of existence.
Aristotle on existence:
Form is what actualizes a potentiality, matter, into an actually existing thing.

4. Aquinas on existence
So for Aristotle, Form brings existence along with it. But for Aquinas, a things existence differs from its essence.
For something imaginary like a phoenix, its essence being form and matter, it lacks existence.
So existence is something added to those substances that do in fact exist.
It is this new understanding of existence which leads Aquinas to rethink God’s existence as unmoved mover.

5. Theism There are 3 general argument patterns for Theism.
Theism, Atheism & Agnosticism
We have so far seen one of these argument patterns:
Ontological Arguments:
Cosmological Arguments:
Teleological Arguments:

6. Aquinas’ 5 ways
The first 4 ways are all different versions of the Cosmological argument and the final way is a version of the teleological argument.
All Cosmological arguments have a form like this:
1. There is something that causes everything else, I.e. a first cause.
2. Only God could be a first cause.
3. Thus, there is a God.

7. Aquinas on the first way
The first and more manifest way is the argument from motion.  It is certain and evident to our senses that some things are in motion.  Whatever is in motion is moved by another, for a thing can be in motion only if it has a potentiality for that towards which it is being moved, while a thing moves insofar as it is actual.  For “motion” means the reduction of something from a state of potentiality into a state of actuality.  But a thing can be reduced from a state of potentiality into a state of actuality only by something already in a state of actuality… Therefore, whatever is in motion must be put in motion by another.  If that by which it is put in motion is itself put in motion, then this also must be put in motion by another, and that by another again.  This cannot go on to infinity, because then there would be no first mover, and, consequently, no other movers—since subsequent movers only move insofar as they are put in motion by the first mover… it is necessary to arrive at a first mover, put in motion by no other, and this everyone understands to be God.

8. The first way The form of the first way: 1) There is motion.
2) Motion is the reduction from a state of potentiality to a state of actuality.
3) Whatever is in motion is moved by another.
4) The cause of any motion must be either an intermediate cause or a first cause.
5) If a causal sequence doesn’t have a first cause, then it doesn’t have a second cause or a third cause, etc.
Thus, 6) It is not possible to have a causal sequence of movers without a first cause. (from 5)
7) Thus, there is a first cause of motion. (from 6)
8) God exists. (from 7)

9. Aquinas’ argument for the 3rd premise
The third premise: 3) whatever is in motion is moved by another.
Question: Must all things be moved by another thing? Is there anything that can move itself?

10. Aquinas’ argument for the 5th premise
5) If a causal sequence doesn’t have a first cause, then it doesn’t have a second cause or a third cause, etc.
Is it possible that we have a sequence of movers without a beginning?
What about a causal loop?

11. Remaining questions about the first way
Can you have a first cause of change if you assume Aquinas’ third premise, that whatever is in motion is moved by another?
What about the move from premise 7 to the conclusion? Is a first cause of change necessarily God?

12. Aquinas on the Second Way
The second way is from the notion of efficient causation.… There is no case known, nor is it possible, in which a thing is found to be the efficient cause of itself, for then it would be prior to itself, which is impossible.  In efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause….To take away the cause is to take away the effect.  Therefore, if there is no first cause…there will be no ultimate cause, nor any intermediate causes.… Therefore, it is necessary to posit a first efficient cause, to which everyone gives the name of God.

13. The Second Way The Second way: 1) efficient causes come in series
Something cannot be the efficient cause of itself for to be so it would have to preexist itself, which is not possible.
And if you take away a cause you take away its effect
2) Such series of efficient causes could not go on to infinity
If the series were infinite there would be no first cause.
If there were no first cause there would be no intermediate causes...
3) So there must be a first efficient cause
4) this everyone gives the name God

14. Questions about the Second Way
If efficient causes come in series then how is a First cause possible?
From premise 3 must it follow that God exists?

15. Aquinas on the Fourth Way
The fourth way is taken from the gradation that is found in things.  Among beings, some are more and some are less good, true, noble, and so on.  But “more” and “less” are said of different things to the degree that they resemble…something that is the most…So there is something that is truest, best, and noblest, and consequently being in the highest degree… What is most complete in any category is the cause of everything in that category… Therefore there must be something that causes the being, the goodness, and every other perfection of all beings, and this we call God.

16. The Fourth Way The fourth way: 1) Some things are good.
2) Some things are better than other things.
3) These better things have more good in accord with their distance from a maximum.
4) whatever is maximally good is the cause of whatever else that is good
5) Thus, something is maximally good and causes everything else that is good (from 1 & 4)
6) This maximally good thing we call GOD.

17. Questions about the Fourth Way
Is premise 4 even true? Is it true that a maximally good thing causes anything else that is good?
Does this principle work for other properties? What about heaviness?

18. Hume on Aquinas’ 5th Way
…[CLEANTHES:] Look round the world; contemplate the whole and every part of it.  You will find it to be nothing but one great machine, subdivided into an infinite number of lesser machines, which again admit of subdivisions, to a degree beyond what human senses and faculties can trace and explain.… The curious adapting of means to ends, throughout all nature, resembles exactly, though it much exceeds, the productions of human contrivance, of human designs, thought, wisdom, and intelligence.  Since therefore the effects resemble each other, we are led to infer, by all the rules of analogy that the causes also resemble; and that the Author of Nature is somewhat similar to the mind of man, though possessed of much larger faculties, proportioned to the grandeur of the work which he has executed.  By this argument a posteriori, and by this argument alone, do we prove at once the existence of a Deity and his similarity to human mind and intelligence.

19. The Fifth Way: the argument from design
1. A machine is the effect of intelligence
2. The world is like a machine
3. Thus, the world is the effect of some intelligence
The argument is:
A posteriori, meaning it is an argument that depends upon experience and matters of fact…
An argument by analogy
A causal argument

20. Critiquing the Argument from design
The first counterargument:
A posteriori arguments are never valid and can never entail their conclusions. Thus, the most the argument from design can give us is probability…
Note: The counterargument above and the next few are taken from David Hume’s Dialogues on Natural Religion…

21. Hume’s next reply
Causal arguments follow this principle: the cause must be proportioned to the effect.
“If the cause be known only by the effect, we never ought to ascribe to it any qualities, beyond what are precisely requisite to produce the effect.” (Enquiry, 190)
But if you look around the world it certainly isn’t perfectly good, intelligent or wise. It seems to have none of the qualities we attribute to God and so cannot prove the existence of a perfect God…

22. The third response to the design argument
If we take the analogy seriously we would be reasoning to something very different than what most take God to be.
Many people often cooperate to make a machine  Many Gods
Wicked people can create technological marvels  a wicked God
Machines are made by mortals  a Mortal God
The best machines are a result of a long history of gradual improvements.
But then “Many worlds might have been botched and bungled, throughout an eternity, ere this system was struck out; much labor lost; many fruitless trials made; and a slow but continued improvement carried on during infinite ages in the art of world-making.” (Dialogues, 36)
What Hume shows us here is that any of these is possible.

23. The final response to the design argument
The universe is “entirely singular”
We can infer the cause of a machine because we have in the past experienced the constant conjunction of machines and designers.
But if we apply this reasoning to the universe, to make a strong argument we would need past experience of the making of worlds, such that worlds are constantly conjoined to designers…