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Thomas Aquinas, M. Guizot in _A_Popular_History_of_France_, Vol. IV.

Thomas Aquinas (detail)


since 01.01.06

Introduction to Philosophy

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, (2) argument from efficient cause, (3) argument from necessary being, (4) argument from gradations of goodness, and (5) argument from design.

  1. Notes for Thomas Aquinas' five arguments are available in six parts. The first part, on this page, summarizes the background of Aristotelian science, and the other five parts are arguments in separate Webpages accessed with the five 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 Argument 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 their existence, there must exist at least one thing that is not dependent and so is a Necessary Being.)
    5. Part IV. The Argument from Gradation. (Since all existent things can be compared to such qualities as degrees of 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.)
  2. 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, reasons, or “causes.” What's responsible or the aitia (αἰτία) is often translated as “causes”; hence the title 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 how natural processes “come about.” 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 for much (scientific) discovery, were dropped in favor of the efficient factor alone, with occasional use of the final factor (especially, as in the biological and social sciences). Francis Bacon states in Novum Organumthat science was unable to progress on account of Aristotle's overly rigid restrictions on explanation—especially in Aristotle's linking natural philosophy to logic.
      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 of a thing accounts for the end or the good of a thing—i.e., what it's for. The development of natural 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. Fruit PickerAs 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 because it is a manufactured object.)
      1. The material factor includes 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 such factors as electricity, gasoline, and human chemical energy sources like adenosine tri-phosphate. Yet, these three general factors are still insufficient for understanding completely the object under inspection.
      4. Thus, it is only when we come to know the purpose of the particular object that enough becomes known so as to constitute knowledge of the phenomenon—we come to know the final or teleological factor: what it's for. The proper function of this object is its use as a fruit-picker.
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“You know the formula: m over nought equals infinity, m being any positive number? Well, why not reduce the equation to a simpler form by multiplying both sides by nought? In which case you have m equals infinity times nought. That is to say that a positive number is the product of zero and infinity. Doesn't that demonstrate the creation of the universe by an infinite power out of nothing? Doesn't it?” Aldous Huxley, Point Counter Point (Urbana-Champaign: Dalkey Archive Press, 2001), 135.

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