I'd change it to "If there is no supporting evidence for the existence of x, then there's no good reason to believe that x exists." — Terrapin Station

But then, what qualifies something as "supporting evidence" ?

As any scientist would contend, evidence is validated via empirical verification. How else can evidence be validated?

If you say that "supporting evidence" is only validated by empirical verification, then there is no need for your amendments to premise 1.

If you say that supporting evidence can be validated by some other means, then we seemingly agree that the original premise 1 is false. But then your modified premise is unclear about what qualifies as "supporting evidence."

Am I missing something?

God doesn't need to predict, he already knows what will happen but knowing and causing are different things. — Jamesk

Now I feel like we need to resolve libertarian/compatibilist free will before getting anywhere. Fat chance on us achieving that!

(I'm an atheist hard incompatibilist anyway, so even fatter chance.)

As sparrows become rarer and humans more common, the exchange rate of humans to sparrows must inevitably decline. In Jesus's day, the average human was probably worth at least 1000 sparrows, but alas, no longer. — Herg

LOL!

Sad thing is, if there is surviving documentation from the period concerning the going rate for domesticated/captured sparrows, an exchange rate for a human life could be worked out... because, y'know... slavery was a thing.

But we're talking about "justice" here. Surely Plato didn't suggest that a philosopher might find the true form of justice via mathematics. Didn't he say that we need to apprehend "the good", and the good is analogous to the sun? The good makes intelligible objects intelligible, just like the sun makes visible objects visible. — Metaphysician Undercover

To be honest, I'm probably due for a refresher on the divided line. I've read the Republic twice, scrutinized books IV, V, and VI, , and written several lengthy papers on it, but it's been over a year since I picked it up and gave it a reread.

What most resonated with me concerning the book was the tripartite soul metaphor and the commentary on how political society regards true knowledge/the knowledgeable. (There are plenty of ideas in the Republic that I don't like, but I've always thought Plato might have intentionally made a book that welcomes disagreement, which is one of the Republic's charms.) Add to that the fact that I'm smack in the middle of Phaedo, and I ended up tossing "turning away from the body" in there. Oops.

As for mathematics, my mentioning of it has to do with some contemplation I did recently after reading Meno for the first time. I gave some thought to what Plato was trying to get at with his theory of forms. I don't really grasp the forms too well... it is unclear to me what Plato is trying to say by postulating their existence. Since Meno contains a lengthy discussion of geometry, I had been considering the forms as "real" in the same way mathematical concepts are real. Anyway, it was just another half-baked, half-developed thought. I'm pretty good for those, unfortunately. But thankfully, I'm occasionally on point to balance things out.

Fear not; you are of more value than many sparrows

Personally, I think I'm worth about 15 sparrows. No more. No less.

Nice analysis there, Herg. That's exactly how I see it, but I don't think I could have put it so clearly.

I suppose an omniscient god might understand free agents in (something like) a quantum superposition before they freely choose an option. So, in principle, it seems possible for free will and omniscience to coexist. This is only an issue with libertarian free will of course. If compatiblism is true, things become much easier for God to predict.

I see where you're coming from. Plato is a bit of a hard-nosed prude.

But keep in mind, his goal is righteousness in the soul. And he repeats often that most are not cut out for his special brand of justice-in-living. Most people are jocks or regular joes just tryin' to get a nut. But some people (very few) are dispassionate by nature. And among those there are some (even fewer) who have strong moral integrity AND are ruled by logic. Plato says to put the wisest in this small group in charge.

Sorry. Just realized I rambled without answering your question. Plato's answer is that the philosopher discovers the form of justice by turning away from the body and investigating truth itself via mathematics, dialectic, and good ol' book learnin'.

Plato's solution is for "Kings to become philosophers and philosophers to become kings." The general public's opinion on how the city ought to be run is irrelevant. Only the guardian class has decision making power in the polis. The rest of the citizens have no political power whatsoever. So the "common opinion" having no grasp of true justice is no problem at all. The city isn't run by common opinion in any way shape or form.

In some respects the Republic is a big "hell no" to the idea that the uninformed masses should steer politics.

How this relates to the soul is this: we have many powerful desires within us. We have blind lust, appetite for unhealthy food etc. We also have powerful emotions in us (such as anger). Like the city ruled by philosophers, our logical part should do ALL of the decision making in our lives. The analogy of the philosopher king represents the most reasonable part of our soul directing our lives. We should not give our desirous or emotional elements any decision making power. We should satisfy our desires and emotional impulses as logic dictates.

Justice and beauty partake in the form of the good. The just city will be just to the extent that it partakes in the form of justice. So too with the just man.

The shadows on the wall of the cave are common opinion. One must turn away from the common opinion in order to see the world as it truly is (ie. behold the forms).

So people and cities do partake in the form of the good and the form of justice. It just takes a philosopher to recognize it.

The analogy used in the Republic is that justice in the soul is too small to be perceived clearly... like little letters on a sign in the distance. But when justice is examined at a large scale, such as a city, what is written becomes larger and easier to decipher.

In short, justice is personal morality wrote large.

As you can see God-dedicated action means acting for the sake of the collective whole. — BrianW

Yes. A charitable reading of the Gita makes room for "selfish" actions. Acting to one's own detriment for the sake of "selflessness" might even be categorized as a sort of delusion by Krishna (see Chapter 1 where Arjuna is moved by compassion toward his enemy and refuses to fight).

As Brian points out, the Gita doesn't prohibit selfish actions. It merely advises one against attachment to the fruits of one's actions. In principle, it is possible to perform an action whose goal is to benefit oneself and also be satisfied if such a benefit is not attained.