Thomas Aquinas, "The Five Ways"

Introduction: The Aristotelian Background

Abstract: Thomas's "Five Ways" (Quinque Viae from the Summa Theologiae) or five proofs for the existence of God are summarized together with some standard objections. The arguments are often named as follows: (1) argument from motion, argument from efficient cause, argument from necessary being, argument from gradations of goodness, and argument from design.

Notes for Thomas Aquinas' five arguments are available via in five parts. The first part is the background of Aristotelian science on this page, and the other four parts are the arguments in the four links listed below:
1. Aristotelian science (this page): The Aristotelian Background
2. Part I. The Argument from Motion. (Thomas argues that since everything that moves is moved by another, there must thereby exist an Unmoved Mover.)
3. Part II. The Argment from Efficient Cause. (The sequence of causes which make up this universe must have a First Cause.)
4. Part III. The Argument to Necessary Being. (Since all existent things depend upon other things for there existence, there must exist at least one thing that is a Necessary Being.)
5. Part IV. The Argument from Gradation. (Since all all existent things can be compared as to such qualities as goodness, there must exist something that is an Absolutely Good Being.)
6. Part V. The Argument from Design. (Also named "The Teleological Argument"— The intricate design and order of existent things and natural processes imply that a Great Designer exists.)
In order to appreciate the cogency of Thomas's five arguments for God's existence, some of the scientific concepts upon which his arguments are based are reviewed: Aristotle's factors of scientific explanation drawn from his Physics and his Metaphysics.
1. A complete explanation, according to Aristotle, for some feature of natural phenomenon must include the following factors or "causes." aitia is often translated as "causes"; hence the reference used in many sources citing these factors is Aristotle's Doctrine of the Four Causes. In point of fact, Aristotle's four factors answer why-questions about natural processes. (Note that modern science only began to progress many centuries later when most of Aristotle's factors, of explanation, which proved to be too rigorous, were dropped in favor of the efficient factor alone, with occasional use of the final factor, as in the social sciences. Bacon notes that science was unable to progress on account of Aristotle's overly rigid restrictions on explanation.)
  1. The material factor: the ultimate substratum of matter consists of the elements from which all particular things arise. Matter is the possibility of form. Matter has the potential to form. A baby is the matter of the form of a child; a child is the matter of the form of an adult.
  2. The efficient factor: the source of the movement of particular things accounts for the generation or the coming to be and the passing away of those particular things. The efficient factor is what is ordinarily meant by the contemporary use of the term "cause." Although change is the actualization of potential, actuality precedes potentiality in that something actual "causes" potentiality to reach another form.
  3. The formal factor: the essence or the form or pattern of particular things. Form is the actuality of matter—not just the shape, but the factor or formation of the potential or the capacity of matter. The ultimate fulfilment of a sequence of forms is the final form or final factor.
  4. The final factor: The purpose oa a thing accounts for the end or the good of a thing—what it's for. The development of natual processes move to completion—what a thing is designed to achieve or do. The internal design of things is part of the ordinary action of natural factors.
2. As an example of the use of Aristotle's four factors of explanation, consider the object in the picture to the right. To explain what this object is, we would include all four factors in our explication. (The manufactured object in the picture was chosen for brevity of explanation with the recognition that this object is not in accordance with of Aristotle's scientific characterization of the natural world.)
  1. The material factor is steel, wood, and paint. From this factor alone, we have not, of course, explained the object.
  2. The formal factor is displayed by the picture in its two-dimensional aspect. The form may be described as an open cage set upon a pole. From this factor in addition to the material factor, we have not given enough of an account to say that we have definite knowledge concerning the object at hand.
  3. The efficient factor is how the form came to be from the material factor or matter. Here, the cause is provided by wood-working tools and metal fashioning tools together with the energy and forces from electricity, gasoline, and chemical energy from adenosine tri-phosphate. Yet, all three factors so far are insufficient for us to understand completely the object.
  4. Thus, it is only when we come to know the purpose of the particular object that enough is known to constitute knowledge of the phenomenon—we come to know the final or teleological factor: what it's for. The proper function of the object is as use as a fruit-picker.

Thomas Aquinas, "The Five Ways"

Philosophy of Religion

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Thomas Aquinas, "The Five Ways"

Introduction: The Aristotelian Background