Proving the God Hypothesis: Aquinas and Al Kindi

 

 

The quest to prove the existence of God has inspired profound philosophical reflections throughout history. Among the notable thinkers who engaged in this pursuit, Thomas Aquinas stands as a prominent figure in Christian theology and Al Kindi in the Islamic tradition. This blog post will present their arguments for God however without explanation. For an in-depth explanation of Al Kindi’s argument read William Lane Craig’s The Kalām Cosmological Argument, and for Aquinas read his Summa Theologica: First Part, Question 2, Article 3 and A History of Philosophy, Vol. 2: Medieval Philosophy - From Augustine to Duns Scotus by Frederick Copleston.

 

Thomas Aquinas (1225-1274 CE):

 

The First Way – Argument From Motion

 

P1. Our senses prove that some things are in motion.

P2. Things move when potential motion becomes actual motion.

P3. Only an actual motion can convert a potential motion into an actual motion.

P4. Nothing can be at once in both actuality and potentiality in the same respect (i.e. if both actual and potential, it is actual in one respect and potential in another).

P5. Therefore, nothing can move itself.

P6. Therefore, each thing in motion is moved by something else.

P7. The sequence of motion cannot extend ad infinitum.

C: Therefore, it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.

 

The Second Way – Argument From Efficient Cause

 

P1. We perceive a series of efficient causes of things in the world.

P2. Nothing exists prior to itself.

P3. Therefore nothing [in the world of things we perceive] is the efficient cause of itself.

P4. If a previous efficient cause does not exist, neither does the thing that results (the effect).
P5. Therefore, if the first thing in a series does not exist, nothing in the series exists.

P6. If the series of efficient causes extends ad infinitum into the past, for then there would be no things existing now.

P7. That is plainly false (i.e., there are things existing now that came about through efficient causes).

P8. Therefore, efficient causes do not extend ad infinitum into the past.

C: Therefore, it is necessary to admit a first efficient cause, to which everyone gives the name of God.

 

The Third Way – Argument From Possibility and Necessity

 

P1. We find in nature things that are possible to be and not to be, that come into being and go out of being i.e., contingent beings.

P2. Assume that every being is a contingent being.

P3. For each contingent being, there is a time it does not exist.

P4. Therefore, it is impossible for these always to exist.

P5. Therefore, there could have been a time when no things existed.

P6. Therefore, at that time there would have been nothing to bring the currently existing contingent beings into existence.

P7. Therefore, nothing would be in existence now.

P8. We have reached an absurd result from assuming that every being is a contingent being.

C: Therefore, not every being is a contingent being (There is a necessary being who is God).

 

The Fourth Way – Argument From Gradation of Being

 

P1. There is a gradation to be found in things: some are better or worse than others.

P2. Predications of degree require reference to the "uttermost" case (e.g., a thing is said to be hotter according as it more nearly resembles that which is hottest).

P3. The maximum in any genus is the cause of all in that genus.

C: Therefore, there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.

 

The Fifth Way – Argument From Design

 

P1. We see that natural bodies work toward some goal, and do not do so by chance.

P2. Most natural things lack knowledge.

P3. But as an arrow reaches its target because it is directed by an archer, what lacks intelligence achieves goals by being directed by something intelligent.

C: Therefore, some intelligent being exists by whom all natural things are directed to their

end; and this being we call God.

 

Al Farabi’s (872-950 CE) posits an argument for the existence of God strikingly similar to Aquinas’ First Way:

 

“In this world, there are things that are moved. Now, every object which is moved receives its motion from a mover. If the mover itself is moved, there must be another moving it, and so on. But it is impossible to go on to infinity in the series of movers and things moved. Therefore, there must be an immovable mover, and this is God.” (Hamond 1947)

 

Al Kindi’s (801–873 CE) argument for the existence of God based on the absurdity of an actual infinity:

 

1. There are six self-evident principles:

(a) Two bodies of which one is not greater than the other are equal.

(b) Equal bodies are those where the dimensions between their limits are equal in actuality and potentiality.

(c) That which is finite is not infinite.

(d) When a body is added to one of two equal bodies, the one receiving the addition becomes greater than it was before and, hence, the greater of the two bodies.

(e) When two bodies of finite magnitude are joined, the resultant body will also be of finite magnitude.

(f) The smaller of two generically related things is inferior to the larger.

2. No actual infinite can exist because:

(a) If one removes a body of finite magnitude from a body of infinite magnitude, the remainder will be a body of either finite or infinite magnitude.

(b) It cannot be finite

(i) because when the finite body that was removed is added back to the remainder, the resultant body would be finite

(a) because of principle I.(e).

(ii) The body would then be both infinite and finite.

(iii) But this is self-contradictory

(a) because of principle I.(c).

(c) It cannot be infinite

(i) because when the finite body that was removed is added back to the remainder, the resultant body would be either greater than or equal to what it was before the addition.

(a) It cannot be greater than it was before the addition

(i) because then we would have two infinite bodies, one of which is greater than the other.

(ii) The smaller would be inferior to the greater

(a) because of principle I.(f)

(iii) And the smaller would be equal to a portion of the greater.

(iv) Thus, the smaller body and the portion would be finite

(a) because they must have limits

α. because of principle I.(b).

(v) The smaller body would then be both infinite and finite.

(vi) But this is self-contradictory

(a) because of principle I.(c).

(b) It cannot be equal to what it was before the addition

(i) because the whole body composed of the greater portion and the smaller portion would be equal to the greater portion alone.

(ii) Thus, a part would be equal to the whole.

(iii) But this is self-contradictory.

3. Therefore, the universe is spatially and temporally finite because:

(a) The universe is spatially finite

(i) because an actually infinite body cannot exist.

(b) The universe is temporally finite

(i) because time is finite.

(a) Time is finite

(i) because time is quantitative,

(ii) and an actually infinite quantity cannot exist.

(b) Time is the duration of the body of the universe.

(c) Therefore, the being of the body of the universe is finite.

(ii) because motion is finite.

(a) Motion cannot exist prior to body

(i) because motion is the change of some thing .

(b) Body cannot exist prior to motion

(i) because the universe is either generated from nothing or eternal.

(a) If it is generated from nothing, body would not precede motion

α. because its very generation is a motion.

(b) If it is eternal, body would not precede motion

α. because motion is change,

β. and the eternal cannot change

(α) because it simply is, in a fully actual state.

(c) Thus, body and motion can only exist in conjunction with each other.

(d) Motion implies time

(i) because time is a duration counted by motion.

(e) Time is finite

(i) because of 3.(b)(i)(a).

(f) Therefore, motion is finite.

(g) Therefore, the being of the body of the universe is finite.

(iii) because the universe is composed.

(a) Composition involves change (motion)

(i) because it is a joining of things together.

(b) Bodies are composed

(i) because they are made up of substance and of three dimensions,

(ii) because they are made up of matter and form.

(c) Motion involves time

(i) because time is a duration counted by motion.

(d) Time is finite

(i) because of 3.(b)(i)(a).

(e) Therefore, motion is finite.

(f) Therefore, composition is finite.

(g) Therefore, the being of body is finite.

(iv) because time must have a beginning.

(a) Otherwise, any given moment in time would never arrive

(i) because infinite time is self-contradictory.

(a) The duration from past infinity to any given moment is equal to the duration from the given moment regressing back into infinity.

(b) Knowledge of the former duration implies a knowledge of the latter duration.

(c) But this makes the infinite to be finite.

(d) This is self-contradictory

α. because of principle I.(c).

(ii) because infinite time could not be traversed.

(a) Before any given moment could be reached, an infinity of prior moments would have to have been reached.

(b) But one cannot traverse the infinite.

(c) So any given moment could never be reached.

(d) But moments are, in fact, reached.

(b) Moreover, future time cannot be actually infinite.

(i) The future consists of consecutive additions of finite times.

(ii) Past time is finite

(a) because of 3.(b)(iv)(a).

(iii) Therefore, future time is finite

(a)   because of principle I.(e).

Now it has been shown that the universe is spatially and temporally finite and why real infinites cannot exist. It is only at this juncture that Al Kindi now identifies the True One as the cause of the universe.

      1. There are several self-evident principles.

2. The universe had a beginning in time.

(a) Time is finite.

(i) Argument from infinite quantity.

(a) No actual infinite quantity can exist.

(b) Time is quantitative.

(c) Therefore, infinite time cannot exist.

(ii) Argument from the selection of the given moment.

(a) To select a given moment in time, we must know what time it is.

(b) If we know what time it is, then we know how long it has been from the given moment back to eternity.

(c) Thus, we know how much time has transpired.

(d) Therefore, time must be finite.

(iii) Argument from the arrival of the given moment.

(a) Before any given moment in time could arrive, an infinite number of prior times would have to be traversed if time were infinite.

(b) But the infinite cannot be traversed.

(c) Therefore, no given moment could arrive.

(d) But this is absurd.

(b) The universe cannot exist without time.

(i) If time is simply duration, then the universe could not exist without duration.

(ii) If time is the measure of motion, the universe could not exist without time.

(a) The universe cannot exist without motion.

(i) If the universe were fully at rest from eternity, it could not begin to move.

(ii) Therefore, there would now be no motion.

(iii) But this is absurd.

(c) Therefore, the universe must have had a beginning in time.

3. The universe could not cause itself to come into existence.

(a) Nothing cannot cause something to exist.

(b) To cause itself, a thing would have to be something other than itself.

4. Multiplicity in the universe must be caused.

5. The cause of multiplicity in the universe is the cause of the universe itself, and it is the True One.

 

“As the True One, the First, is the cause of the beginning of the motion of coming to be, ... it is the creator of all that comes to be. As there is no being except through the unity in things, and their unification is their coming to be, the maintenance of all being due to its unity, if [things which come to be] departed from the unity, they would revert and perish. . . . The True One is therefore the First, the Creator who holds everything He has created, and what¬ ever is freed from His hold and power reverts and perishes.” (Craig 1979)