The Second Way of Thomas Aquinas

The Second Way of Thomas Aquinas

                In this essay we will continue on our analyzation of the natural theology of Saint Thomas Aquinas and his many arguments for the existence of God. As with my post on the first way, a keen understanding of Aristotelian metaphysics is needed to have an accurate conception of the said arguments, so referring to my first post is needed decently heavily. The second way is an argument from the efficient causes that frequently occur within our world, and the need for a being whose essence is existence. The argument is commonly in the form of:

  1.    We perceive a series of efficient causes of things in the world.
  2. Nothing exists prior to itself.
  3. Therefore nothing [in the world of things we perceive] is the efficient cause of itself.
  4. If a previous efficient cause does not exist, neither does the thing that results (the effect).
  5. Therefore if the first thing in a series does not exist, nothing in the series exists.
  6. If the series of efficient causes extends ad infinitum into the past, for then there would be no things existing now.
  7. That is plainly false (i.e., there are things existing now that came about through efficient causes).
  8. Therefore efficient causes do not extend ad infinitum into the past.
  9. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.

First in analyzing this argument we need to go over the weighterer terms. An essence is the whatness of a thing. For example the whatness or quiddity of a camera would be cameraness. Things possess an essence conjoined to an esse, or existence, but an essence is entirely separate from the act of  existence a being possesses (In all things but God as we will see from the argument).  An efficient cause is a cause that brings something into being, in the most common example, the efficient cause of the David would be Michelangelo and his tools, and in the case of a mountain, in many cases it would be erosion.

As in the first way, the argument relies on the  absurd implications of an actually infinite essentially ordered series without a first cause, but not against the concept of the actual infinite as a whole. An essentially ordered series is one in which each member is reliant on an intermediate member for an effect, hence every member must function for the series to go on, in a roughly simultaneous manner. If a potency ceases to be actualized, so will the series. This is also not an attack on series ordered per accidents in which a series will continue after termination of another member. In the most popular example, Abraham begets Isaac, Isaac begets Jacob, and Jacob begets Joseph and so forth. If say Abraham dies, the series can still continue even after the termination of Abraham (and it did). Aquinas’s objection to this carrying on in an essentially ordered series can be summed up in an example with moons.  If seven moons in a series relying on the first moon for light have no potency to create light on their own, extending said series to infinity will not suddenly make said series have the potency to  achieve self-lighting. Even if we grant said movers extends to infinity, something would still have to be instilling within them causal powers from outside of the series. So this argument is not an attack on the finitude or lack thereof, of the universe.

Now on to the argument!

  1.  Premise one seems uncontroversial for any sincere truth seeker, things clearly are brought about, and these are generally the result of efficient causal relations. These include not only the substances of our everyday experience, but also the accidents that exist through a substance. 
  2. Premise two also seems uncontroversial, for something to exist prior to itself entails a contradiction, and hence I fail to see this as a valuable tool for evading the implications of the proof. It would both have to exist and not exist in the same respect, and since it is plausible simuatenous causality is true, this makes the absurdity even more definite, it will exist and not exist within the same event.
  3. Premise three does follow logically from the other premises, and hence to deny it leads to the strongly  argued conclusion nothing creates itself, because if a being did, a previous un-existing potency for existense would be required within be actualized by a being that exists, which is contradictory since they are the same being (being is used broadly here, accidents work fine for this as well), hence Aquinas’s conclusion should follow working through the implications. This is by no means making the claim that everything that exists requires a cause, which Aquinas would clearly never make, he was a pretty intelligent guy.
  4. Premise four seeks to show that without an existing cause explanatorily prior, the effects of the cause cannot exist, which plausibly follows from the other steps.
  5. As hinted at earlier, premise five is working through the implications of an essentially ordered series extending indefinitely. Even if there was no  first temporal cause that brought something into existence, a being would be needed to give the series itself a potency or proclivity to function. This is why Aquinas’s arguments are not temporal arguments ie, the universe could be eternal on the view of these arguments, although the Third way implies the universe is in fact finite in the past, although it is not even needed there.
  6. Premise 6 follows as well due to the argument that it seems  illogical to posit that a series of contingent causes would  be a sufficient explanation in the series even thought the act of existence intrinsically in a finite one is absent.  Extending this to infinity would yield nothing.
  7. Premise seven is also clear for any sincere truth seeker. Things clearly do exist now, and have been brought about by efficient causes. Even to think said statement in the case of man would be to have been the result of some prior efficient cause, and this also applies you abstracting the idea of this article. This brings me to an  interesting thing about Aquinas’s arguments, that they explore why things exist at the present moment rather than not, and hence it isn’t an argument for a sort of deistic God. His family of arguments explore why things exist here and now first and foremost, and hence without the act of being, nothing could exist at any point. Necessarily everything is reliant on God’s creative powers as the primary cause of all things here and now, since an escence is not a cause in any real sense. As Aquinas would say


“that the act of existing itself be caused by the form or quiddity – and by ‘caused’ I mean as by an efficient cause – for then something would be the cause of itself and produce itself in existence, which is impossible”

Which means that existence has to be conjoined to an essence. For example, if these things do not have existence conjoined with their essence, there is no reason at all for their essence to naturally be existent,  as the essence of a turtle with and without the act of existence is exactly the same. This is clearly contrary to  the interventionist view of God professed by most Theistic personalist’s like Plantinga and Swineburne.

8. Premise eight follows logically, limited amount to explain.

9.Hence Premise nine concludes resoundingly stating that something exists in which the essence is identical with it’s existence, is the primary cause and creator of all things, and that would be what all declare as God. The same arguments from the previous post can be used to argue for God possessing an intellect, (That is the best way to word it) as this points to the same being, as existence itself  is an actualized potential, and God is pure existence/being itself as Actus Purus, and hence the Prime Mover and first cause. Logical possibility is itself a potency, which needs to be remembered. 


Overall, as with the first way, the second way is a successful argument in natural theology. The argument is really quite great, but it probably a bit too metaphysic heavy to explain adequately to the novice in this area. We will review the Third Way in my next post, which relies heavily on the prior two arguments for one of its most potent solutions. Thank you for reading and God bless you all! 


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