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Introduction to Logic: God Exists
Portfolio Assignment
Andrew Wirawan
August 9th, 2011

Part 1. IDENTIFY THE ARGUMENT
I Transcript (see below)

2.Context : Philosophical Proofs on the Existence of God, by St. Thomas Aquinas. The great Catholic thinker, philosopher and theologian St. Thomas Aquinas summarized his cosmological argument in the Summa Theologia. In this theological masterpiece, St. Thomas writes five "ways" that we can know God exists. The first “three” ways was described above.

3.Argument
Premise 1: Every being that exists or ever did exist is a dependent being or there exists a self-existent being.
Premise 2: Not every being can be a dependent being.
Premise 3: Therefore, there exists a self-existent being.

4. Source: Aquinas' Cosmological Argument, by Adrian Samuel , http://www.richmond-philosophy.net/rjp/rjp20_samuel.php


PART 2. TRANSLATION
D: Every being is a Dependent being.
S: There exists a Self-existent being.

Part 3. Proof

1. Valid? Yes, this argument is valid.

2. Method of Natural Deduction
1. D v S
2. ~D / S
3. S 1,2 DS
3. Method of Truth table
D S D v S ~D //S
T T T F T
T F T F F
F T T T T
F F F T F
There is no row where both premises are true and the conclusion is false. Since the argument is not invalid, it must be valid.


Transcript:
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“…..The first way explores causality under the aspect of movement, and the argument can be characterized as follows: firstly, things in motion are experienced as being put in motion by something else (e.g., a billiard ball striking another), and secondly, appealing to the principle of sufficient reason, there must be a first mover that is the sufficient reason for all the things in motion.

Aquinas' second way claims that 'efficient causality' assumes a first cause... Aquinas' claim is that the process of shaping something (which we experience in the 'forms' we encounter) needs to have a first efficient cause to initiate that process.... Now Aquinas understandably believes that this process of explanation must itself mirror a causal process of events. Furthermore, the reality of later events derives from the reality of previous events. If the causal process were to be infinite, events would be infinitely borrowing their reality from previous events, but there would nothing real to initiate this act of borrowing. It would be analogous to claiming that I could possess money, if I borrow it from someone else, who borrows it from someone else, etc., even if there was no original money! There must therefore be a real event to initiate the process of bringing about other events - and this is the first cause.

`This way starts with contingency and necessity, and discusses whether everything might be merely contingent (i.e., exist at one moment and not at another).] The argument can be presented as follows.

If everything is contingent, everything is subject to time (to passing in and out of time). This would mean that time is ultimate - the basic framework of all existence. There would therefore be nothing to limit the movement of time, so time would be infinite. In infinite time, all possibilities are played out, including the possibility that everything ceased existing (this is of course possible, given that everything is contingent). At a moment in the infinite past therefore, there would have been nothing. Experience however teaches us that nothing comes from nothing, meaning that if this were true, it would also be true that there is nothing now. This is clearly false as we do not experience the world to be nothing, so the whole scenario that led to this conclusion must be false, including the claim that everything is contingent. If everything is not contingent however, we need to conclude that there is at least one thing with necessary existence.

'Therefore we cannot but postulate the existence of some being having of itself its own necessity, and not receiving it from another, but rather causing in others their necessity.' (Summa 1: 2: 3)

This argument is a reasonably complex one, and fails if any of its premises fails. Nevertheless, this way seems to most clearly reveal the principle of sufficient reason, which is arguably assumed by all of Aquinas' ways. For it claims that underlying everything that happens to exist there must be an essential necessity for that existence - the sufficient reason, which is the source of its own necessity.”

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