Pro
#1
I would like to start by thanking RationalTheist for accepting the debate and hope that it is as engaging as I hope.
To start off my opening arguments, I think we can start with the Diversity of Religious Experience.
DIversity of Religious Experience argument for Polytheism
This argument ultimately comes from John Michael Greer’s book A World Full of Gods, but Dr. Bowers has a fantastic YouTube summary of the argument that is linked below.
Greer presents an analogy of a researcher visiting a village with the goal of understanding the villager’s views on the existence of cats.
When the researcher interviews the first villager, the existence-exclusive mono-felist, the villager says that they obviously believe in the existence of Cat. There is one Cat, they say, and they have seen it. It is a tabby with blue eyes. I will leave out kibble for it in the mornings and by the end of the day it is gone. This villager also says that they know some of their neighbors have different views of Cats, which is sad since those cats don’t exist. They are leaving the wrong types of food and believing the wrong things about Cat. The food they leave out is probably just eaten by wandering hobos.
The researcher then goes to the next house to ask them about Cat. This villager, the value-exclusive mono-felist goes on to say they obviously believe in the existence of Cat. There is one Cat, they say, and they have seen it. It is a black cat with green eyes, and every morning they leave milk out for Cat and by the end of the day it is gone. They know some of their neighbors claim to have experience with Cat, but says they are just experiencing sewer rats and mistaking them as Cat. They think some might think they are feeding Cat while mistakenly feeding the rats, but also suspects some are purposefully feeding the rats.
The researcher then moves to the third house to ask the same questions. This villager, the existence-inclusive mono-felist, goes on to say they obviously believe in the existence of Cat. There is one Cat, they say, and they have seen it. It is a marmalade tom with orange eyes. They know some of their neighbors claim to have experience with Cat, and do not deny it (after all, they get some details correct), but say the neighbors are mistaken in certain ways. They probably only saw Cat in the dark or bad lighting conditions, causing them to get a bad look at Cat and mistake its characteristics. They leave out canned food every day, as they know that Cat prefers it over all else, though Cat probably also eats the kibble and milk, but it is canned food that Cat likes best of all.
We can skip the fourth house for the debate, as it is the house of the a-felinist and thus not entirely relevant to the debate.
So, finally the researcher makes it to the fifth house, the house of the poly-felist. This last villager informs the researcher that there have been three different Cats in the village for a while now, each with its preferred foods that they know where to go to get. What is funny is recently, they go on, is that they say they recently saw burmese Cat recently show up in the village and is curious to know what the other villagers will make of it when they see it.
The first three villagers are analogous to different monotheist positions one can take:
The first villager represents the monotheist that thinks all other Gods are fake and that people that claim experience of other Gods are delusional.
The second villager represents the monotheist that thinks all other Gods are something other than Gods (think of the particular Christians that hold that other religions worship demons), and that other people are either mistakenly worshipping demons or are doing so intentionally.
The third villager represents the monotheist that thinks others are worshipping God, but that their perceptions are flawed. Think of the Blind Men and the Elephant story (linked below).
The problem with these views is that they all, ultimately, rely on special pleading.
Each view is that their own experiences are valid (or at least anyone that would hold the same views), but that other experiences are not. Whether they think the experience of other Cats/Gods is due to delusion, mistaking something else for Cat/God, or just an imperfect lens does not change the special pleading involved.
Even if we take a modified variation of villager three, one that holds there is one Cat/God but no one’s experience is more valid than the other, this still does not explain it when people have experiences involving multiple Cats/Gods at once.
Only the person that acknowledges many Cats/Gods (or none at all) can avoid special pleading when it comes to explaining the diversity of religious experience. And so a diversity of religious experiences, which is what exists, better supports polytheism than monotheism.
Gödel's Incompleteness Theorem and Mathematical Platonism
This argument is ultimately derived from Willdam20’s argument on Reddit (linked below).
I do not think presuming Mathematical Platonism is true should be too controversial, as in the latest Phil Survey, linked below, the majority, not just a plurality, of Philosophers of Mathematics hold to this view. I will, however, still make a small case for it at the end of this section.
If abstract objects do exist in a Platonic manner, there are two main ways that they can be conceived of within philosophy.
Either they exist as independent, necessary things.
Or they exist within the mind of God(s).
If the former, then that means that there can exist multiple necessary things, which weakens monotheism’s probability.
If the latter, then Willdam’s argument becomes useful in establishing polytheism.
His argument is as follows:
P1) A God (in general) possesses a perfectly rational intellect.
P2) The product of a single perfectly rational intellect ought to be complete and consistent.
P3) If Divine Conceptualism is true then mathematics is the product of at least one divine mind.
P4) By Gödel's Incompleteness Theorem, no system of mathematics is both complete and consistent.
P5) If Divine Conceptualism is true then mathematics is not the product of a single divine mind.
P6) Mathematical Platonism, and specifically Divine Conceptualism, is true.
C) Therefore, there exists more than one divine, perfectly rational mind, i.e. Polytheism is true.
P1 and P3 are definitionally true.
God, in a classical sense, is a perfect being, and an irrational intellect would preclude a being from being perfect.
Divine Conceptualism is definitionally that abstracta, which mathematics is (under Mathematical Platonism), are products of the mind of God(s).
P2 seems to also follow from God’s perfect nature. If God is perfect and Omnipotent, then it seems contradictory for God’s mind or the product of said mind to include either incompleteness or inconsistency.
P4 is also just a restatement of Gödel's Incompleteness Theorem.
It seems like if one wishes to hold to Divine Conceptualism as the explanation of Mathematical Abstracta, while also adhering to the perfect nature of God(s), that one must hold that Mathematics is a product of multiple Divine Minds coming together. Each mind is consistent and, with the union of another Divine Mind, creating a complete mathematics.
Or you can reject Divine Conceptualism, hold that Mathematical Abstracta (and other abstracta) exist as their own, independent necessary entities. In that case, that means there can be things that exist that are not dependent upon one God, and that leaves the door open for polytheism.
I expect the challenge to this argument will mostly be on P6, denying Mathematical Platonism.
So, what reasons are there to accept Mathematical Platonism? One of the best arguments is, I believe, the Indispensability Argument (the SEP article is linked below).
The gist of the argument is that we are ontologically committed to the existence of Mathematical Abstracta in the same way that the field of electronics is ontologically committed to the existence of electrons.
To quote the basic argument from the SEP article,
P1) We ought to have ontological commitment to all and only the entities that are indispensable to our best scientific theories.
P2) Mathematical entities are indispensable to our best scientific theories.
C) We ought to have ontological commitment to mathematical entities.
Much of science would not work without mathematics. Mathematical entities are, essentially, necessary for science to work. If mathematical entities do not exist, then it would seem strange that science seems to work and produce empirically true results.
One of the main ways that those that argue against the Indispensability Argument typically try to do is try and eliminate science’s reliance on mathematics (see Hartry Field’s Science Without Numbers). This has mostly been considered unsuccessful as it seems, especially within higher level physics, chemistry, etc., mathematics is necessary.
An Ontological Argument for Polytheism
The final argument in my opening arguments is, what I believe to be, the strongest argument for polytheism (granted theism as true).
P1) A necessary being exists in all possible worlds.
P2) If the Principle of Identity of Indiscernibles (PII) is not necessarily true, then there exists at least one possible world with many necessary beings.
P3) The PII is not necessarily true.
C1) There exists a possible world with many necessary beings.
C2) There exists many necessary beings, i.e. Polytheism is true.
P1 is definitionally true within modal logic.
P2 seems to be obviously true. The PII is the principle that there must be a property, outside of mere numerical distinction, between two things for them to exist (SEP article linked below).
Essentially, when applied to theism, the argument usually goes that there must be some property that one God has that the other does not, for if there were no differences then (via the PII) there is only one God.
Which means that P3 is the contentious premise.
There are two ways that I will support P3, starting off with the traditional means of using Max Black’s thought experiment, included in the SEP link, (and giving my own twist):
Max Black asks us to imagine a symmetrical universe with only two balls in it, each in perfect symmetry. Intuitively, there is nothing that seems to be wrong with the existence of such a universe. The only thing one can point to on why such a universe would be metaphysically impossible seems to be that such perfect symmetry would violate the PII, but such reasoning alone seems absurd.
But we can go one step further.
Let’s imagine a collection of universes. In every single one of these universes there exists two balls. What causes each universe to be different is the color of the balls, specifically each ball can be red, orange, yellow, green, blue, or violet in a different combination.
The position of the balls within the universe are such that if they are the same color, that the universe is a symmetrical universe with the balls in perfect symmetry.
So, the question is why can each ball, Individually, be any of the available colors while they cannot both be the same? It seems, to me, like the PII, when applied to this hypothetical collection, is absurd, and thus via reductio ad absurdism should be dismissed.
But as much as I enjoy the various thought experiments one could have with symmetrical universes, it turns out that we don’t even need them to reject the PII. Why? Because we already know it is false due to quantum mechanics as bosons violate it!
Unlike fermions, bosons can occupy the same quantum state as each other.
To quote from Identity in Physics: A Historical, Philosophical, and Formal Analysis,
“it is not the case that in practice we cannot distinguish between two photons, but, rather, that there is nothing in principle which can serve to individuate them [...]Furthermore, the photons existing in mode P are not identical to the ones before or after, and are excitation of the same field mode and possess all properties in common, yet are numerically distinct, PII is violated."
Nick Huggett has even gone further into looking at the applicability of the PII to quantum mechanics and found it wanting (link below).
We are, ultimately, left with no good reason to accept the PII as true, let alone necessarily true. As such, P3 is established, and thus the argument follows, so long as there exists at least one necessary being (God), there are many, and thus polytheism is true.
Conclusion
I hope that my opening arguments have, at the very least, given thought to pause and consider polytheism. I hope that I have convincingly showed that both human experience and logical deduction lead us to polytheism as being probably true (at least, when granted that theism is true)
Sources:
A World Full of Gods by John Michael Greer
The Logic of Polytheism by Dr. Bowers (https://youtu.be/R2l7jo-apXI?si=Fwvikv6pgJxHFs9C)
Blind Men and the Elephant (https://en.wikipedia.org/wiki/Blind_men_and_an_elephant)
Willdam20’s An Argument for Polytheism (https://www.reddit.com/r/Defense_of_Polytheism/comments/woyf3h/an_argument_for_polytheism_using_platonism_g%C3%B6dels/)
2020 Phil Survey (https://survey2020.philpeople.org/survey/results/4818?aos=47)
SEP Indispensability Argument (https://plato.stanford.edu/entries/mathphil-indis/)
SEP Principle of Identity of Indiscernibles (https://plato.stanford.edu/entries/identity-indiscernible/)
Identity in Physics: A Historical, Philosophical, and Formal Analysis by Steven French and Decio Krause
Quarticles and the Identity of Indiscernibles
Nick Huggett (https://philpapers.org/rec/HUGQAT)