The Cosmological Argument:

St. Thomas of Aquinas (1225-1274 CE)
5 Ways of Knowing God Exists:

1. Argument from Motion (First Mover) -

P1. There is motion (movement, change) in the universe.

P2. Everything which is in motion must be moved by something else (i.e., nothing moves itself).

P2.1 The change from potential to actual motion can only occur in things potentially in motion.

P2.2 Only actual things can cause actual motion.

P2.3 It is impossible to be both potentially and actually in motion at any given time.

C. Therefore, every change from potential to actual motion is caused by something other than the thing in motion.

P3. There cannot be an infinite regression of movers.

C. Therefore, there must be a First Mover; and, the First Mover is God.

2. Argument from Causation (First Cause)-

P1. Every material effect has an efficient cause.

Note: Aristotle's theory of Causation - The Four Causes
  1. 'Material' - the substance of a thing
  2. 'Formal' - the shape (or form) of a thing
  3. 'Final' - the purpose of a thing
  4. 'Efficient' - the antecedent condition which brought about the effect

P2. Nothing is the efficient cause of itself.

P3. There cannot be an infinite regression of efficient causes.

C. Therefore, there must exist a First Efficient Cause (which is caused by nothing else), and this is God.

3. Argument from Contingency (Argument From Necessity)

P1. Some things exist contingently.

P2. All contingent things fail to exist at some time.

P3. If everything were contingent, there would have been a time when nothing existed.

P4. If there was a time when there was nothing, there would be nothing now.

P5. But, something does exist now.

C1. Therefore, there must exist at least one thing which is not contingent (i.e., that exists necessarily).

P6. All necessary things either do, or do not have an efficient cause.

P7. An infinite regression of efficient causes is impossible.

C2. Therefore, here must exist at least one necessary thing which is the efficient cause of all contingent necessities, and this is God.

4. Argument from Excellence (Degrees of Perfection)

P1. Things have properties to a greater or lesser degree.

P2. Superlative judgements depend upon comparing the imperfect with the perfect.

P2.1 Things with the greatest degree of a property must exist.

P2.2 Things with the greatest degree of a property are the cause of that property in less perfect things.

P3. There must exist something with the highest degree of being.

C. Therefore, there must exist a perfect being (which is the cause of imperfect being), and this is God.

5. Argument from Harmony (A Teleological Argument)

P1. Material objects are aimed at some end/goal.

P1.1 Material objects act/move consistently toward the same end/goal.

P2.The end/goal at which material objects aim is not random.

P3. Material objects are incapable of guiding themselves toward their end/goal (because they lack the knowledge to do so).

C. Therefore, something exists with knowledge which guides material objects to their ends/goals, and this is God.

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