I'm really tempted to ask if, 6 years after you first wrote this, you've explored new materialist ideas about biology and physics because this feels like it's becoming (pardon the dorky pun, heh heh)

I couldn't go through the entire arguments.

I understand that. I was hoping you could at least get one started, though, if it's actually possible to do what you say can be done.

it follows rationally from our first principle, our assumption.

You yourself called it an assumption. It is not an assumption if you can deduce it from the First Principle.

Think about it

Why me? You're the one trying to prove something. And the argument "It's obvious" doesn't count as a proof of anything.

As I mentioned in a previous comment, going through all this would be to argue for an entire metaphysics, which would be the subject of a book. Unfortunately, because I must respect other commitments I have, I couldn't go through the entire arguments.

And so you now have two assumptions.

Think about it--If you assume that the physical cosmos exists, then you can't rationally hold that "existence/being isn't true". That makes no sense. "The physical cosmos exists" and "thinks don't exist" are contradictory.

So we are not assuming that existence/being is, it follows rationally from our first principle, our assumption.

I'm not proposing an argument above.

You're supposed to be showing that it is possible to argue from your First Principle to Aristotle's metaphysics without assuming anything except the First Principle. One assumption, no more.

To say that the "world exists" is simply to say that "being is". That's all that I am assuming.

And so you now have two assumptions.

But to identify this proposition with some concept of being is to sneak an additional premise into the argument, it seems to me.

To say that the "world exists" is simply to say that "being is". That's all that I am assuming. We start with being/existence.

-----

Remember, I'm not proposing an argument above. This is just an basic outline of what would need to be argued about. The main point I was simply pointing out is that, after point (1), we could use reason to show the others to be true or false. We don't need to assume that they are true. The only one we need to assume to be true is that "the world is".

1) First Principle: "Being", i.e, the material world exists, which we are a part of.

Your original statement was: the only assumption, or "First Principle", that Aristotle needs for his ontology (i.e., metaphysics) is that the cosmos exists. I suggest we leave it at that. I don't object to equating the cosmos with the material world, nor with the stipulation that we part of it. But to identify this proposition with some concept of being is to sneak an additional premise into the argument, it seems to me.

2) As part of this world we experience internal and seemingly external experiences.

I'm not entirely sure that this can be deduced from the First Principle, but I'll stipulate it for the sake of discussion.

3) Use reason to show how the senses are reliable and we are able to be "in contact" with this external material world.

I don't think the First Premise by itself can get you there.

4) We observe these material objects and how they act.

That looks to me like an instantiation of premise 2 with respect to material objects.

5) We use deductive and inductive reasoning to show that for objects to exist as we observe them to actually exist, material, efficient, formal, and final causality must all be at work.

Here you are just restating your claim that we can infer Aristotle's metaphysics from the single premise asserting the existence of the cosmos. You are not demonstrating how this might actually be accomplished or even that it can be accomplished. You are simply asserting, "It can be done."

I get it that a complete reproduction of the argument might be too long to fit in a single forum post. But in that case, to even get started, you have to do something like the following:

Let U be the proposition "The universe (or cosmos, or material world, whatever) exists" and M be the proposition conjoining all the assertions of Aristotle's metaphysics.
In that case:
Assume U.
If U then A.
If U then B.
If A and B, then C.
Therefore, C.
If U then D or E.
If D then F.
If E then F.
Therefore, F.
If C and F, then . . . .
[until we get to]
. . .
Therefore, M.

And at no point in all of this do we assume anything other than U, except for auxiliary assumptions that are discharged before the conclusion is deduced. For particular example, "If U then A" cannot be an assumption. It must be proved by a demonstration that the conjunction "U and ~A" constitutes or entails a contradiction.

You say you would include inductive reasoning. I'm OK with that, but it just means you get to use propositions of the form "If P, then probably Q," which means you have to demonstrate the improbability of "P and ~Q" being true.

1) First Principle: "Being", i.e, the material world exists, which we are a part of.

Your original statement was: the only assumption, or "First Principle", that Aristotle needs for his ontology (i.e., metaphysics) is that the cosmos exists. I suggest we leave it at that. I don't object to equating the cosmos with the material world, nor with the stipulation that we part of it. But to identify this proposition with some concept of being is to sneak an additional premise into the argument, it seems to me.

2) As part of this world we experience internal and seemingly external experiences.

I'm not entirely sure that this can be deduced from the First Principle, but I'll stipulate it for the sake of discussion.

3) Use reason to show how the senses are reliable and we are able to be "in contact" with this external material world.

I don't think the First Premise by itself can get you there.

4) We observe these material objects and how they act.

That looks to me like an instantiation of premise 2 with respect to material objects.

5) We use deductive and inductive reasoning to show that for objects to exist as we observe them to actually exist, material, efficient, formal, and final causality must all be at work.

Here you are just restating your claim that we can infer Aristotle's metaphysics from the single premise asserting the existence of the cosmos. You are not demonstrating how this might actually be accomplished or even that it can be accomplished. You are simply asserting, "It can be done."

I get it that a complete reproduction of the argument might be too long to fit in a single forum post. But in that case, to even get started, you have to do something like the following:

Let U be the proposition "The universe (or cosmos, or material world, whatever) exists" and M be the proposition conjoining all the assertions of Aristotle's metaphysics.
In that case:
Assume U.
If U then A.
If U then B.
If A and B, then C.
Therefore, C.
If U then D or E.
If D then F.
If E then F.
Therefore, F.
If C and F, then . . . .
[until we get to]
. . .
Therefore, M.

And at no point in all of this do we assume anything other than U, except for auxiliary assumptions that are discharged before the conclusion is deduced. For particular example, "If U then A" cannot be an assumption. It must be proved by a demonstration that the conjunction "U and ~A" constitutes or entails a contradiction.

You say you would include inductive reasoning. I'm OK with that, but it just means you get to use propositions of the form "If P, then probably Q," which means you have to demonstrate the improbability of "P and ~Q" being true.

Obviously going through an entire philosophical system would be a book; but here would be a basic flow (I don't have Aristotle in front of me to put how he did it, but this is how I would personally lay it out)

1) First Principle: "Being", i.e, the material world exists, which we are a part of.
2) As part of this world we experience internal and seemingly external experiences.
3) Use reason to show that these external experiences are real and how the senses are reliable.
4) Observe external world that we have reason now to believe actually exists.
5) We can now observe these material objects and how they act.
6) We use deductive and inductive reasoning to show that for objects to exist as we observe that they do, material, efficient, formal, and final causality must all be at work.

That would be a very general outline!

Really the only assumption, or "First Principle", that Aristotle needs for his ontology (i.e., metaphysics) is that the cosmos exists.

I don't think so. How about a demonstration? Show us how someone could, without assuming anything else, deduce another proposition from "The cosmos exists."

Really the only assumption, or "First Principle", that Aristotle needs for his ontology (i.e., metaphysics) is that the external world exists. That's it.

And as I was pointing to above, science's underlying assumptions are that Aristotle's metaphysics is mostly correct. In other words, ontology (metaphysics) always precedes every other science and realm of study, in the order of knowledge.