This is part 3 in a 5 part series.  You can find the other parts here (part 1, part 2, part 4, part 5)

The third way in which Thomas Aquinas reasoned toward the existence of God deals with the question of being and not being.  Here’s how the argument goes:

From observation, we can see that the things around us in the world have the possibility of existing or not existing.  For example, the computer you are now using to read these words, exists now but has not always existed.  There was a time when the computer was not (at least in its present form).  For something (like the computer) to move from non-existence to existence, that action had to be brought about by something or someone that was already in existence.  In other words, for the computer to come into being, it had to be manufactured or made…. and to manufacture something you must “exist” or “be.”  Something that does not exist cannot make another thing come into existence.  Thus, all things that exist must be brought about by that which exists.  There must be a “first being” through whom all things that do exist came about.

And if that first being exists, he must out of necessity, have never “not existed.”  In other words, since non-existence cannot bring about existence, the first being necessarily has to have always existed.  And this entity that necessarily exists and cannot not-exist, is God.

O.K. – what do you think?