Lesson 25B Preview: Fr. Barron Videos “Thomas Aquinas” and “Aquinas’ Five Arguments”; Thomas Aquinas Videos;  Video “The Cosmological Argument of Thomas Aquinas with Craig Commenting”

Fr. Barron of the Chicago Diocese offers an extraordinary, though regrettably brief, discussion of some of Thomas Aquinas’  gifts to Christians: clarity on the deceptions of the Two Truths Doctrine, the nature of contingency and contingent life, and the full humanity of Christ as a foundation for a vibrant Christian Humanism:

Here is a second brief reflection that again contains a very important reference to Aquinas’ Five Arguments for the Existence of God. His experience as a teenager answers, in effect, the question “Why should modern Christians spend time learning Aquinas’ Five Arguments?”

Here is an outstanding video providing an excellent summary of Aquinas’ Five Arguments:

This excellent video places Thomas Aquinas in an historical-biographical context:

Aquinas’ Arguments for the Existence of God have led to the development of a modern argument known as the Cosmological Argument. In the video below, on Aquinas, William Lane Craig is briefly interviewed about the cosmological argument along with other professors:

Time and the Kalam Cosmological Argument is the subject of a carefully thought and certainly well-written response to a student’s letter about a “refutation” he had heard. Please click here to go to the reasonablefaith.org site where, if you have not already registered, you will need to. Dr. Craig does not charge for enrolling. Go to this page on the site to obtain the password.

Leibniz and the Cosmological Argument are the subject of this well-conceived inquiry from another philosophy student to Prof. Craig. You will find this question and answer an excellent introduction to Leibniz’ modification of the traditional Cosmological Argument formulation. Please click here.

William Lane Craig: In this optional learning experience Craig debates Sam Harris at Notre Dame University, this full 2 hour debate (click here to go to the debate at Youtube or go to the Bonus Lesson where it is also embedded) presents Dr. Craig responding to this atheist’s arguments against God.

The Bonus Lesson focuses on William Lane Craig’s Best Arguments. It is tucked behind Lesson 26B. Click here if you would like to listen to these as some content will also contribute to answers for the questions below.

Bible Verses for Reflection: Luke 2: 28-32; Gal 1: 11-12; Eph 1: 15-17

A Quote for Your Consideration: “For that which is above reason we believe only because God has revealed it.” (Thomas Aquinas, Book IV, Summa Theologica)

Questions for Discussion:

Before you plunge into writing answers to the questions below, you may benefit from consulting an essay Dr. Craig wrote,  The New Atheism and Five Arguments for God,  that summarizes his position on arguments that are reflected in these community college students’ questions. (Click on the title after you have signed in at his website and you will jump to the article at ReasonableFaith.org. It is printable.)

1. Apparently your panel’s presentation at the college philosophy class went so well the Philosophy Department was buzzing the next day about this huge success [see Lesson 24B]. In fact, your instructor friend talked to a colleague who has asked you and the rest of the panel to return to present to his class as well.

During the Q & A a student asks, “When a Christian tells me that God loves everyone, even the sinner, I ask how can a morally perfect God love the sinner who defies Him and causes harm to those around him? I usually get some kind of answer saying God ‘hates the sin and loves the sinner’. How is this really possible? Isn’t it more reasonable for God to hate the sinner and the sin? Doesn’t the Old Testament present us with a God who does a lot of hating? He tells the Israelites to kill men, women, and even babies. What’s that all about?”

[Please see Craig’s response to this, and a number of other related issues at this page. You may also want to go back to the Plantinga bonus lesson tucked behind 24B and review the videos Does Evil Disprove God’s Existence? ]

2. “Some of you theists”, says another student looking directly at you, “seemed to be claiming in your argument for the existence of God that “God is a necessity” .  She continued, “I have hit a roadblock with this idea of God having a necessary existence. I understand what it means in a logical sense for something to necessarily exist . Yet when you talk about metaphysical necessity, I think it is called de re necessity, my brain gets muddled. As I understand it, to say that God necessarily exists in the metaphysical sense, or  de re, you mean to state that in every world in which God possibly exists, God must exist. Help me understand what you are getting at with this part of the argument, which my friends back here tell me was taken from Aquinas – or  maybe it was Anselm. Whatever. It’s going over my head.” What will you say to this student to get it into her head?

[ Please see this page for Craig’s ideas when formulating your response. Don’t forget of course Dr. Plantinga’s comments in his video Is God a Necessary Being? embedded in the Alvin Plantinga Bonus Lesson.]

3. Apparently a student in this philosophy class has had some previous exposure to Aquinas’ Five Arguments for the Existence of God or Leibniz, specifically he is about to present to you a modern form of the Cosmological Argument:

The student begins, “I have an argument here you theists like to use. It’s built on these  premises: [at this point the student takes out a scrap of paper and starts reading to the panel]

‘(1)Everything that has a beginning of its existence has a cause of its existence.

(2)The universe has a beginning of its existence.


(3) The universe has a cause of its existence.

(4) If the universe has a cause of its existence then that cause is God.


(5) God exists.’

I just don’t get how you guys can justify this conclusion that God exists? Is it because all around us we can see the physical universe existing and you think all of that plus some astrophysics and shazam we have an argument. Maybe you guys are thinking I am just another biased atheist, but I really think you theists are illogical. You just manipulate words that have nothing to do with God’s existence. Who can explain this argument and convince us it is a ‘proof’ of God’s existence?” He sits down smiling and seeming very satisfied with his comments. How will you respond?

[See this page for assistance in formulating your contribution to the panel’s response. You may also find the Bonus Lesson: Craig On Best Arguments useful, particularly his video presentations on The Cosmological Argument, as well as his videos on Leibniz who developed his own variation of the Cosmological Argument.]

4. A student walks up to as you sip a cup of coffee and mingle with students following the Q & A session. The young man blurts out, “I really liked your ideas, but you seem to believe in an absolute morality. But isn’t everything we decide we must do really just based on rules that are  relative? I mean relative to a specific situation – and relative to what you have been taught to believe is good or bad…like I believe there really isn’t anything in itself that is good…it’s just what we have been taught to believe is good by our parents, or teachers, or maybe a pastor…like not lying or stealing or cheating on tests in school.” Having seen a few video debates with Craig, you feel better prepared to give a response in language this young man can understand. What will you say?

[You might find it useful to consider Craig’s summary on The Moral Argument  at the Bonus Lesson . See this web page at ReasonableFaith.org for help in formulating an answer to the student. Scroll down after reaching this page at Reasonablefaith for the entry “God provides the best explanation for the existence of objective moral values in the world.”]

Glossary of Names and Terms: Please click on the concept and you will jump to a source document.

1. Thomism (see #9 below)

2. The Quinque Viae – The Five Ways of Aquinas

3. Arguments for the Existence of God

4. Dominic

5. Dominican Order

6. Natural Theology

7. Averroes

8. Avicenna

9. With the decree Postquam sanctissimus of 27 July 1914, Pope Pius X  declared these 24 principles below were the basis for sound Catholic doctrine; thus, these teachings from  Catholic scholars, who shared the Pope’s orthodoxy, are intended to embody Thomism and, thereby, Aquinas’  contribution to modern Roman Catholic theology. Pope Pius X was the first Pope canonized since Pius V , leader of the counter-reformation in the sixteenth century.


  1. Potency and Act divide being in such a way that whatever is, is either pure act, or of necessity it is composed of potency and act as primary and intrinsic principles.
  2. Since act is perfection, it is not limited except through a potency which itself is a capacity for perfection. Hence in any order in which an act is pure act, it will only exist, in that order, as a unique and unlimited act. But whenever it is finite and manifold, it has entered into a true composition with potency.
  3. Consequently, the one God, unique and simple, alone subsists in absolute being. All other things that participate in being have a nature whereby their being is restricted; they are constituted of essence and being, as really distinct principles.
  4. A thing is called a being because of “esse”. God and creature are not called beings univocally, nor wholly equivocally, but analogically, by an analogy both of attribution and of proportionality.
  5. In every creature there is also a real composition of the subsisting subject and of added secondary forms, i.e. accidental forms. Such composition cannot be understood unless being is really received in an essence distinct from it.
  6. Besides the absolute accidents there is also the relative accident, relation. Although by reason of its own character relation does not signify anything inhering in another, it nevertheless often has a cause in things, and hence a real entity distinct from the subject.
  7. A spiritual creature is wholly simple in its essence. Yet there is still a twofold composition in the spiritual creature, namely, that of the essence with being, and that of the substance with accidents.
  8. However, the corporeal creature is composed of act and potency even in its very essence. These act and potency in the order of essence are designated by the names form and matter respectively.


  1. Neither the matter nor the form have being of themselves, nor are they produced or corrupted of themselves, nor are they included in any category otherwise than reductively, as substantial principles.
  2. Although extension in quantitative parts follows upon a corporeal nature, nevertheless it is not the same for a body to be a substance and for it to be quantified. For of itself substance is indivisible, not indeed as a point is indivisible, but as that which falls outside the order of dimensions is indivisible. But quantity, which gives the substance extension, really differs from the substance and is truly an accident.
  3. The principle of individuation, i.e., of numerical distinction of one individual from another with the same specific nature, is matter designated by quantity. Thus in pure spirits there cannot be more than individual in the same specific nature.
  4. By virtue of a body’s quantity itself, the body is circumscriptively in a place, and in one place alone circumscriptively, no matter what power might be brought to bear.
  5. Bodies are divided into two groups; for some are living and others are devoid of life. In the case of the living things, in order that there be in the same subject an essentially moving part and an essentially moved part, the substantial form, which is designated by the name soul, requires an organic disposition, i.e. heterogeneous parts.


  1. Souls in the vegetative and sensitive orders cannot subsist of themselves, nor are they produced of themselves. Rather, they are no more than principles whereby the living thing exists and lives; and since they are wholly dependent upon matter, they are incidentally corrupted through the corruption of the composite.
  2. On the other hand, the human soul subsists of itself. When it can be infused into a sufficiently disposed subject, it is created by God. By its very nature, it is incorruptible and immortal.
  3. This rational soul is united to the body in such a manner that it is the only substantial form of the body. By virtue of his soul a man is a man, an animal, a living thing, a body, a substance and a being. Therefore the soul gives man every essential degree of perfection; moreover, it gives the body a share in the act of being whereby it itself exists.
  4. From the human soul there naturally issue forth powers pertaining to two orders, the organic and the non-organic. The organic powers, among which are the senses, have the composite as their subject. The non-organic powers have the soul alone as their subject. Hence, the intellect is a power intrinsically independent of any bodily organ.
  5. Intellectuality necessarily follows upon immateriality, and furthermore, in such manner that the further the distance from matter, the higher the degree of intellectuality. Any being is the adequate object of understanding in general. But in the present state of union of soul and body, quantities abstracted from the material conditions of individuality are the proper object of the human intellect.
  6. Therefore, we receive knowledge from sensible things. But since sensible things are not actually intelligible, in addition to the intellect, which formally understands, an active power must be acknowledged in the soul, which power abstracts intelligible likeness or species from sense images in the imagination.
  7. Through these intelligible likenesses or species we directly know universals, i.e. the natures of things. We attain to singulars by our senses, and also by our intellect, when it beholds the sense images. But we ascend to knowledge of spiritual things by analogy.
  8. The will does not precede the intellect but follows upon it. The will necessarily desires that which is presented to it as a good in every respect satisfying the appetite. But it freely chooses among the many goods that are presented to it as desirable according to a changeable judgment or evaluation. Consequently, the choice follows the final practical judgment. But the will is the cause of it being the final.


  1. We do not perceive by an immediate intuition that God exists, nor do we prove it a priori. But we do prove it a posteriori, i.e., from the things that have been created, following an argument from the effects to the cause: namely, from things which are moved and cannot be the adequate source of their motion, to a first unmoved mover; from the production of the things in this world by causes subordinated to one another, to a first uncaused cause; from corruptible things which equally might be or not be, to an absolutely necessary being; from things which more or less are, live, and understand, according to degrees of being, living and understanding, to that which is maximally understanding, maximally living and maximally a being; finally, from the order of all things, to a separated intellect which has ordered and organized things, and directs them to their end.
  2. The metaphysical motion of the Divine Essence is correctly expressed by saying that it is identified with the exercised actuality of its own being, or that it is subsistent being itself. And this is the reason for its infinite and unlimited perfection.
  3. By reason of the very purity of His being, God is distinguished from all finite beings. Hence it follows, in the first place, that the world could only have come from God by creation; secondly, that not even by way of a miracle can any finite nature be given creative power, which of itself directly attains the very being of any being; and finally, that no created agent can in any way influence the being of any effect unless it has itself been moved by the first Cause.

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