5. The Design Argument

This is the fifth and final argument of Saint Thomas Aquinas in his famous "five ways". 

Despite the apparently erratic occurrences taking place at a subatomic level, there is an incredible amount of order and purpose in our world.  Things exist and coexist with beautiful order and regularity.  It is normal for many different beings to work together, such as organs in our body.  This order is either the product of 1) chance or 2) intelligent design.  If chance, consider the following analogy from Scott Hahn's Reasons to Believe:

Is the human intellect capable of imagining that kind of process?  Yes, but its implausible.  In a similar way, when you study creation, you see evidence for design, and design points to a designer.  The eye is a system of irreducible complexity, composed of a retina, cornea, lens, vitreous humor and aqueous humor.  It cannot simply be the result of an arbitrary process.  The eye is made with a certain design, made for the purpose of seeing; and each of its parts assumes the functioning of all the other parts...The eye is made with an end in mind: to see.  This is true for everything else, from subatomic particles and cells to solar systems and galaxies.  The empirical sciences themselves are possible only because the universe is orderly, patterned, symmetrical, observable, and (to some degree at least) measurable and predictable. 

Furthermore, "chance" is not a credible alternative to design.  Chance only makes sense when order is assumed.  When things happen "by chance" they are unexpected.  But, as Peter Kreeft and  Ronald Tacelli point out in The Handbook of Catholic Apologetics, "expectation is impossible without order."  If you remove order and only consider chance, you have removed the only thing that allows us to speak of chance at all.  Instead of thinking of chance against a background of order, we are invited to think of complete and total order against a random and purposeless background of chance.  This is unreasonable and quite incredible.(Paraphrased from The Handbook of Catholic Apologetics, pg. 61)

We may reasonably conclude that the device on the beach had a manufacturer, and that the manufacturer had a purpose in mind when making it.  A watch requires a watchmaker.  In a similar way, an ordered universe requires the existence of an intelligent creator; and we call that creator God.  (Reasons to Believe, pg. 35)