Thomas Aquinas sets forth five proofs for the existence of God in the Summa Theologiae (see Prima Pars, Quaestio II, Articulus III, Responsio):
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, because that which does not exist only begins to exist by something already existing. Therefore, if at one time nothing was 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. But every necessary thing either has its necessity caused by another, or not. Now it is impossible to go on 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.Some critics of the argument charge Aquinas with committing the "quantifier shift fallacy." For more information regarding this fallacy, see https://www.oxfordreference.com/view/10.1093/oi/authority.20110803100357607
However, Edward Feser has defended the third way from the quantifier shift fallacy, and so have others as you'll see below:
https://edwardfeser.blogspot.com/2011/06/on-some-alleged-quantifier-shift.html
https://mvstconference.ace.fordham.edu/themataphysicsofaquinas/john-ocallaghan/
(The link above insists that Thomas Aquinas' third way does not commit the quantifier fallacy)
https://www.researchgate.net/publication/315353402_The_Validity_of_Aquinas%27_Third_Way
(This page likewise argues that the third way is logically valid)
While I support the conclusion of the third way, and I think the argument is forceful, it might need tweaking as Robert E. Maydole does in his article, "Aquinas' Third Way Modalized," wherein he applies modal logic to the third way. See https://philpapers.org/rec/MAYATW
24 comments:
"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." - what would be a good example of this?
He's talking about everything sense object that we see around us daily. For example, an oak tree is generated from an acorn. It lives for a determinate period of time, then dies. So we conclude that its existence is possible (contingent) but not necessary like God's.
That should be every, not everything
Humans and animals are in the same boat. We come into being but eventually pass away.
https://analogia-entis.medium.com/notes-on-aquinas-third-way-cb3a518b96dc
https://medium.com/age-of-awareness/the-environmental-keyword-you-probably-havent-heard-of-b55305961f6
I believe that the principles demonstrated by this go far beyond ecosystems. To say that we have ecosystems (plural) could be misleading. We have biomes and clustering but the earth is a single ecosystem. It goes beyond beginnings and endings, as we see them. Seeds germinate under specific conditions, how long they can sit dormant is unknown. The condition of the soil is indicated by the seeds that germinate. Low energy areas have much greater diversity and redundancy. High energy areas are almost monoculture, but where the two meet has the highest diversity. Change the condition of an area of soil and plants germinate that are different to previously known.
I wonder if this could be reformulated as a contingency argument (like Leibniz or Samuel Clark) and avoid the fallacy? I also wonder if John Duns Scotus's argument from First Principle has the force of the third way without the supposed fallacy?
Duncan, while ecosystems certainly can illustrate Aquinas' point, he lived way before we started using these concepts and the language of ecosystems. The main reason I posted the link from medium.com is because the writer talks about hylomorphism (matter & form entities) which is Aristotelian philosophy that influenced Thomas Aquinas. If one looks at trees as hylomorphic entities, then it might lead someone to conclude that trees could not be the cause of their own existence: they must be possible/contingent. If we generalize across nature, the principle coule apply to more than just trees. But Aquinas is making an a posteriori case for the existence of a necessary being (God). He is reasoning from effects to the first cause of all things. That would include ecosystems or biomes.
The Stanford Encyclopedia of Philosophy has Scotus' argument written out and explained along the way: it doesn't seem to commit a fallacy or the same one, but his argument is long and involved. See https://plato.stanford.edu/entries/duns-scotus/#ProExiGod
Feser and a host of others think there is no fallacy in the third way, and their explanations for why there's not make my head spin. I've read Leibniz and Clark, and it's possible that their versions could avoid the fallacy, if there is one in Aquinas.
Joshua Rasmussen has an article about the contingency argument. It seems that the fallacy some like to use in that case is the fallacy of composition, but I've encountered replies to accusations of that fallacy too.
https://joshualrasmussen.com/articles/the-argument-from-contingency.pdf
But a tree is built from preexisting matter/energy. The energy is never lost, it shifts and fluxes. Where does a tree begin? Is it when a new tree grows from a seed or is it the very first seed in the chain? When did the chain begin?
If I were to mold a plastic into a tree shape, color it in the right way and allow it to sway the correct way in the breeze - it that treeness?
What is the difference between a tree and a bush? Is it size? bushes can be as large.
Is it the number of trunks? We have multi stem trees.
We put all into our own little pidgin holes and give them names.
Moss and fungi are built to destroy, that is there purpose. They reconfigure matter.
https://allabout-moss.com/is-moss-a-fungus/
Is each configuration an expression if ecotone - not the ecology but rather the energy flux/streams.
First, I think we have to remember that Aquinas is writing in the 13th century CE and using hylomorphism to produce a great narratival synthesis. Furthermore, the third way/proof is not dependent on whether the tree first came into existence or not. His issue is whether trees/material objects/the universe are possible in the sense of being contingent (not necessary).
Just off the top of my head, I can think of philosophers who have dealt with some of the questions you're asking, like Plato, Aristotle, and Peter van Inwagen. But "treeness" for Aristotle just means having the form or property of a tree. I believe he primarily has natural objects in mind, not things that art works of artifice. Form has a technical meaning in Platonic and Aristotelian thought: both thinkers use the term but is different ways.
IMO, a tree may be built from preexisting energy, but that leaves the question, what's the original source/origin of the energy? Every house has a builder but he that built/made all things is God. Personally, I've never seen anything come into existence without a cause.
But have you seen energy come into existence?
Aquinas said we don't have to know whether something had an origin to know that it's contingent. I've never seen energy come into existence. As one scientist said, I wasn't there when energy and matter came into being. ☺
"I wasn't there when energy and matter came into being." Didn't he conflate?
Is energy contingent? Can you image a circumstance where it would not exist?
I think you know this, but when scientists talk about energy, they're talking about something that's measurable and defined by relativity theory, etc. In other words, energy as manifested in the physical/material word. So energy as we know it, in that sense, seems contingent.
To put it another way, physical energy as we know it, did not have to exist.
https://www.thermal-engineering.org
Some comments on Rasmussens contingency argument :)
https://musingontheology.wordpress.com/2022/09/10/joshua-rasmussens-argument-from-contingency/
Thanks :-)
@E.Foster isn't the trinity dogma a needless complication of this line of reasoning though? If Aquinas is saying that the first cause is absolutely necessary wouldn't this rule out the kind of redundancy in which trinity results?
@aservantofJehovah, if you ask me, it does needlessly complicate things. However, Aquinas tries to demonstrate God's existence without proving he's triune. He famously compartmentalized God and the three persons.
Aquinas thinks reason can demonstrate that God exists, but it takes divine revelation to arrive at the view that God is triune.
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