The Fifth Way of St. Thomas Aquinas: The Argument from Final Ends
- We see in the natural order that there are things that lack intelligence that nevertheless act toward an end.
- But, whatever lacks intelligence cannot move toward an end unless it is directed to do so by a being that possesses intelligence.
- Therefore, there must be an intelligent Being that directs all natural things toward their end, and this Being we call God.
We all recognize that there are things in nature that lack intelligence that, even still, act always or almost always toward the same result, or final end. Planets follow orbits. Cells convert sugar into energy. Flowers produce nectar that hummingbirds then eat. They “almost always” act toward these ends because there are factors that can influence, or even inhibit, them from reaching the intended end. But, this only reinforces the argument, since we recognize these anomalies as anomalies precisely because they fail to meet what we know is their expected end. Yet, none of these things have intelligence. None of these things can be said to plan these ends and act rationally and intelligently toward meeting them. There must, then, be some intelligent Being that is directing all of nature toward these ends, and that Being is God.
Thomas doesn’t claim here that everything has a final end toward which it acts. Rather, he claims that everything that acts toward an end has an end toward which it acts that isn’t random, but purposeful, as can be observed by the fact that the actor “always, or nearly always” acts toward that end, and not some other. Rocks may fall in a random pattern during an avalanche, but acorns always grow into oak trees. Molecules may bounce about in any given random pattern, but electrons always orbit neutrons, never the other way around, and two hydrogen atoms bonding with one oxygen atom will always produce a water molecule. It’s because of this regularity, this purposeful activity in nature, that nature can be studied scientifically. We can predict the outcomes of certain natural phenomena because we deduce, consciously or not, the final end inherent in them, whether or not we deduce the existence of the One Who directs them toward that final end. No one doubts that water boils at 100 degrees C at sea level and, furthermore, we know it will boil at a lower temperature rather than a higher temperature at higher elevations. It’s because of this regularity that we can engage in scientific experiments and gain further knowledge about the created order. It’s also because of this regularity that we can manipulate the created order, for a surgeon would never open a knee looking for a heart.
Be Christ for all. Bring Christ to all. See Christ in all.