In response to a Thomist who said that they don't know whether the fourth way holds water or not and they don't care...
I think it matters a lot if it holds water, because the assertion that it doesn't underlines a fundamental objection to the broader general validity of all Aquinas' arguments; that people now simply understand the world better than they did then. He's not just making abstract arguments about metaphysics and philosophy, he's making concrete statements about the physical world and how it works, so his level of correct understanding about the physical world is highly relevant. Saying that fire causes all hot things is just the best, most obvious example of how Thomas Aquinas had fundamental misconceptions about nature, reality, and science, which has an impact on all five of the ways. They're kinda just variations on a theme, that "there has to be X because there can't be Y," and when you really get right down to it, I feel like "well how would you know there can't be Y" is the only response any of them need.
When Aquinas says things like "motion is nothing else than the reduction of something from potentiality to actuality" or "whatever is in motion must be put in motion by another," I think those are things which appeal to common sense, but shouldn't be taken for granted as factual just because they seem sensible at a glance. And when we stop and consider how they're said by someone who thinks that fire is the source of all heat, one might start to wonder whether they're really even that sensible to begin with. (Note that I'm not making a genetic fallacy here, I'm not saying the arguments are automatically wrong because they came from a guy who doesn't understand what heat is. What I am saying is that it's worth scrutinizing more carefully the statements and arguments of someone who purports to make empirical observations about what is and must be in reality, when he doesn't understand very basic things about reality -- in the same category that he's speaking about -- that we now know to be true.)
To me, saying that fire is the source of all heat is similar to saying that the earth is still and the sun spins around it. That seemed like common sense until a deeper scientific understanding showed that it was false. Saying things that are in motion need to be put in motion by something else seems just as sensible as saying that the earth is flat. Common sense is not proof, but common sense is all Aquinas has. When Aquinas says in the fifth way that things without intelligence can't possibly act for an end without something having designed them, that would have seemed like common sense to the people of his time, but we now can see that he's displaying a severe ignorance about how evolution and natural selection push a species toward the most effective pursuit of an end (passing on their genetic material) without any need for an intelligence to design them. While it might still seem like common sense to say that things in motion need to have been put in motion by something else, I don't think Thomas Aquinas has a sufficient level of scientific understanding to comment on how motion actually works in the real world. And even if he's right that things in motion need to have been put in motion by something else, it's still not common sense to say that the one exception to that rule is the God he just happened to already believe in by faith.
Don't you think it's at least possible that the fourth way is so weak because he simply started from the conclusion that God exists and worked backwards?
https://www.reddit.com/r/DebateReligion/comments/mccgvq/definitions_created_about_god_are_not_proof_that/gs47rts/
In response to someone who said that the OP obviously hadn't read the Five Ways because they didn't understand concepts that would only be evident if they had read a lot more than the Five Ways (not long after the discussion that the above excerpt came from, and after noticing a pattern of Thomists saying that people who criticize the Five Ways don't really understand them).
Personally, I feel like Thomist apologists or debaters want to have their cake and eat it too. They want to act like the Five Ways are just straightforward, common sense observations that God must exist based on simple realities of how the world works, but then when people point out the deep flaws in those straightforward formulations, they also want to act like you need to read multiple full volumes before you can make any informed criticism of the Five Ways.
And sure, you may be right that the OP's criticisms of the Five Ways miss the mark. But the opaqueness of these arguments cuts both ways. It's possible that reading Summa Contra Gentiles and whatever else would make me convinced that the god you believe in is real. But it's also possible that reading the Qu'ran (if I first took the time to learn a new language so I could appreciate it in it's most authentic form) would make me convinced that the Muslim god is real. And more to the point, it's possible that reading all the relevant supplementary texts of these arguments would just make me more informed about how full of fallacies they are.
In other words, if you're saying that we can't actually understand the arguments until we've read and understood all the relevant context, then we have just as little reason to think the arguments are true as we do to think the arguments are false, until we've done the reading. You could not reasonably assert that someone must read SCG and various other things before declaring the arguments false, but the plain reading of the arguments by themselves is enough to declare them true. That would be highly irrational. So then, Thomists who insist that criticisms of the Five Ways lack context also give up any claim to have presented any compelling arguments for God's existence, at any length that the average reader of this sub would be willing to work their way through.
Now of course, you're probably thinking, "well, if you did read all of the relevant materials, then you'd see that my position is right." But see, I don't owe you the reading of all those supplementary materials, just like I don't owe Muslims the reading of various hadiths, or Mormons the reading of The Pearl of Great Price (just like you don't owe atheists a reading of full volumes by Russell or Hume). You have to give people a reason to think it's worth putting in the time to read your particular theological text, and "these arguments seem easily refutable in a straightforward, standalone reading, but they're actually not" isn't a great selling point for drawing me into the rest of Aquinas' theological perspective (especially since there are still so many people who treat the Five Ways themselves as compelling arguments to prove the existence of God).
Honestly, not even trying to be relevant to this particular thread anymore. This is the third thread about Aquinas I've seen in about a week, so I just felt like expressing some general thoughts about my frustration with the apparent elitism of it. If you don't feel like reading through it all or replying, I'm okay with that. I almost started a separate thread, but I just don't care that much. The bottom line is, I'm not gonna read every theological book ever written, and nothing any Thomist has said in any of these discussions has given me any reason to believe I should elevate Aquinas to the top of the stack. So if you can't express a contextually-accurate formulation of Aquinas' arguments within the character limit of a single Reddit post, then I'll continue to think there are no good reasons to conclude your god exists, until such time as I decide to read the relevant context for my own edification.
https://www.reddit.com/r/DebateReligion/comments/mf3goy/thomas_aquinas_five_ways_to_prove_the_existence/gsp3nfi/
