Thomas Aquinas and 5 deductions on the existence of God

This is Part 1 in a 5 part series.  Follow the links to the other parts  (Part 2, Part 3, Part 4, Part 5)

Thomas Aquinas is one of those “old dead theologians” many on the scholarly side of Christianity will refer to from time to time.  He was no slouch when it came to theology, or logical argumentation for that matter.  Not to say that he got everything right… but he did a very good job with the talents God entrusted to him.  I pray I do half as well…


Aquinas suggested 5 “ways” as he called them, that argument could be made toward the existence of God.  Now bear in mind, logic alone can’t get you to the “Christian” definition of God, and Aquinas wasn’t saying that it could.  The arguments he makes could just as well lead you to Allah, or Zeus, or some other “god” as it could the Biblical God.  However, his arguments are helpful in thinking through the issue, in logical and sensible terms, of whether or not a “higher power” or “creator” exists at all.  I’m going to take the next few posts to cover Aquinas’ “5 ways” one at a time… so here goes with the first…


The first of the “ways” has to do with observations Aquinas made regarding the nature of motion (sounds like Physics class… I told you Aquinas was no slouch).  Good old Thomas realized that for motion to take place, say for a ball to move, there had to be something that interacts with it to cause it to move.  It must be struck by another object, like a bat or a foot or a golf club.  The ball has the potential to move, but that potential cannot be realized until something else acts upon it.  Make sense so far?

From here Aquinas argued that as the original object that was moved (the ball) needed to have something act upon it to move, so too the object which struck it (the bat) had to have something act upon it in order for IT to move.  Are you following?  The ball moved because the bat hit it… but what made the bat move?  The arms of the man!  But what made the arms of the man move?  The muscles in his arms! …and so on and so forth, backward and backward in the chain of cause and effect…  Are you still with me (or Thomas)?

In thinking this through, Aquinas realized that this chain of cause and effect would HAVE to continue backward eternally.  But that seemed such a ridiculous and absurd idea to him, and was not consistent with observable evidence (and I must agree with him there).  So he concluded that there must be a “first mover” who sets the chain into motion.  This “first mover” would have to be independent of the laws of the universe, able to move of his own will, without the necessity of something moving upon him in order for him to move.  In order for that to be true, this “first mover” must be an infinite being outside of creation, and therefore would be God.

So what do you think?  Did Aquinas get it right on this one?


5 thoughts on “Thomas Aquinas and 5 deductions on the existence of God

  1. Pingback: Reasoning Toward God – Thomas Aquinas’ 5 ways « the passionate follower’s journal

  2. Pingback: Way 3 of reasoning toward God – Thomas Aquinas « the passionate follower’s journal

  3. Pingback: 4th Way of Reasoning Toward God – Thomas Acquinas « the passionate follower’s journal

  4. Nope.
    An infinite number of events is perfectly plausible, and, in fact, observable. Every action, from start to finish, no matter how large or small, has a midpoint. Then the “distance” between the beginning and the midpoint also has a midpoint. One can divide any action an infinite number of times like this. Each action is in fact an infinite number of fractional actions.

    If each action, or movement, to use Aquinas’ word, is infinitely divisible and still whole, then an infinite number of such actions is possible as well. An infinitely long movement, which is essentially what the universe is, can be divided infinitely into less and less inclusive infinities without need of a beginning or an end.

    Infinity divided by infinity is one, not zero.

    One could bring up Planck time here to dispute me, i.e. time has a minimum scale on which it works and therefore can only be divided so far. This is a misunderstanding of Planck time. It is not a property of time itself, only an estimated limit at which our math can meaningfully function. It is a mathematical limit, not a conceptual one.

    • Your example does not show an infinite number of events, but an infinite number of divisions of an object. They are very different both in concept and in reality.

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