Sunday, March 06, 2011

The Fifth Way in Syllogistic Form


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I. From ST I.2.3c:

The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.


II. The Argument in Syllogistic Form:

Major: If something that lacks intelligence is moved towards an end (m), then it is directed by some being endowed with knowledge and intelligence (i).
Minor: We see that things which lack intelligence are moved towards an end (m).
Conclusion: Therefore, all natural things that lack intelligence are directed to their end by some being endowed with knowledge and intelligence--and this being we call 'God' (i).

Example of the Major: As the arrow is shot to its mark by the archer.
Example of the Minor: Natural bodies. This is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end.


III. Syllogistic Structure (simple modus ponens):
Major: m ---> i
Minor: m
Conclusion: i


IV. See also:

3 comments:

Anonymous said...

Can anyone provide some insight as to how St. Thomas' Fifth Way relates to contemporary theories of Intelligent Design? Is there any correlation? It seems to me that ID at least the way it is most often understood is quite unclear and lacking a clear and defined foundation in metaphysical causality...

Don Paco said...

It seems both arguments (Aquinas' Fifth Way and the modern Intelligent Design argument) have the same structure (modus ponens). But one major difference is that Aquinas' antecedent in the major speaks not of things that illustrate a 'design' but things that illustrate 'movement toward an end'. Similarly, the conclusion is not that there is an 'intelligent designer' but

Why is this significant? Aquinas says more. The Intelligent Design argument is compatible with deism (the idea that God once created the world and left it to run on its own). The God of the Intelligent Design argument could have designed the world once, and left it to run by itself. But the creatures in Aquinas' Fifth Way are continuously dependent on God for reaching their ends.

I do not reject the intelligent design argument--I think it ultimately works--but I think Aquinas has more to offer.

Jonathan said...

Dr. Ed Feser has a lot to say about Intelligent Design vs. the Fifth way in his book on Aquinas, and, I believe, in his book refuting the New Atheism. It's very interesting.