3. The Thomist Cosmological Argument

Key Person: Thomas Aquinas (1225-1274)

Thomas Aquinas was a scholastic philosopher and Dominican whose work had an enormous influence both on the course of Christian theology and on the course of philosophy generally. Aquinas is particularly well known for his “Five Ways,” five proofs for the existence of god which rely upon the use of reason and empiricism rather than revelation. He is known as the champion of Catholic orthodoxy, and his work Summa Theologica is regarded as a magnus opus in Christian doctrine.

In the Thomist position we return to Aquinas’ five ways to prove God’s existence. The first three are cosmological in nature and are somewhat complementary but with some differences.

The first and more manifest way is the argument from motion. It is certain, and evident to our senses, that in the world some things are in motion. Now whatever is in motion is put in motion by another… If that by which it is put in motion be itself put in motion, then this also must be itself put in motion, and that by another again. But this cannot go on to infinity, because then there would be no first mover, and consequently, no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.

 The second way is from the nature of the efficient cause. In the world of sense we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for it would be prior to itself which is impossible. Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several or one only. Now to take away the cause is to take away the effect. Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause. But if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.

The third way is taken from possibility and necessity and runs thus. We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be. But it is impossible for these always to exist, for that which is possible not to be at some time is not. Therefore, if everything is possible not to be, then at one time there could have been nothing in existence. Now if this were true, even now there would be nothing in existence, it would have been impossible for anything to have begun to exist; and thus even now nothing would be in existence- which is absurd. Therefore, not all beings are merely possible, but there must exist something the existence of which is necessary. Now it is impossible to go to infinity in necessary things which have their necessity caused by another, as has been already proved in regard to efficient causes. Therefore we cannot but postulate the existence of some being having of itself its own necessity, and not receiving it from another, but rather causing in others their necessity. This all men speak of as God.  

Aquinas draws on the work of Aristotle in his discussion; he does not claim to be developing a new argument, rather Christianising and bringing coherence to a previously stated one. Copleston and others have highlighted a problem with Aquinas’ linear succession of movers and causes. Michael Palmer has argued that

Aquinas’ argument would go something like this: Suppose I observe a chain of upright dominoes stretching beyond the horizon and out of sight. When I later observe each domino falling and causing its neighbour to fall, I must conclude that this chain has a beginning in a domino that was not itself caused to fall. Why so? Because a chain of dominoes reaching back over an infinite duration of time would presumably take an infinite length of time to reach those dominoes I now observe falling, and would not thus reach those dominoes. It is accordingly only by presuming a first domino that I can account for the immediate and indisputable experience I have of dominoes being caused to fall (2001:53).

Anthony Flew describes this as a “peculiarly gross howler” (1971:192). Why?

Key Person: Anthony Flew (1923)

British philosopher and atheist (for most of his career)- has written many books about atheism and the critique of God.

Copleston clarifies or amends Aquinas’ argument by suggesting not a temporal first cause but an ontological first cause “which is not part of a series stretching back into the past but of a ‘hierarchy of efficient cause being dependent on the cause above it in the hierarchy” (Palmer, 2001:53).

What he [Aquinas] is thinking of can be illustrated in this way. A son is dependent on his father, in the sense he would not have existed except for the causal activity of his father. But when the son acts for himself, he is not dependent here and now on his father. But he is dependent here and now on other factors. Without the activity of the air, for instance, he could not himself act, and the life-preserving activity of the air is itself dependent here and now on other factors, and they in turn on other factors. I do not say that this illustration is in all respects adequate for the purpose; but it at least illustrates the fact that when Aquinas talks about an ‘order’ of efficient causes he is not thinking about a series stretching back into the past, but of a hierarchy of causes, in which a subordinate member is here and now dependent on the causal activity of a higher member. If I wind up my watch at night, it then proceeds to work without further interference on my part. But the activity of the pen tracing these words on the page is here and now dependent on the activity of my hand, which in turn is here and now dependent on other factors (Copleston, 1955:122)

In the Thomist (or even Kalam) Cosmological argument it is possible that there may have been a first mover but its work is now done, and therefore it may provide evidence that there was once a God but not that this God still exists. God as the pusher of the first domino who then lets events unfold is not the God most people worship, rather they would believe in a God who is both transcendent and immanent.

Not only is God the cause of the first cause but is the continuing power behind every cause since the first one. Copleston draws a distinction between two types of causes. A cause in fieri suggests something which causes an effect to become what it is, while a cause in esse is one which sustains the being of the effect.

Identify if the following reflect an in fieri or an in esse cause.

Dr. Holt wrote this workbook.

James is large because he eats chocolate.

Lucie is learning RE.

Greg is a talented musician because he practices.

Lowri works at Nando’s because she did excellently in her interview (obviously).

Sahdia’s clothes shopping result in lovely matching outfits (with bag and shows too!!!)

The Kalam Cosmological Argument

The Thomist Cosmological Argument as understood by Copleston.


Because Aquinas argues that all life is contingent, it is possible that it could not have been, and it owes its original and continued existence to an ontologically necessary being –God.