I was pondering in philosophy class, and I think I came up with a pretty good argument that the universe is not contingent.

First off, lets us set up the definitions I am using to frame this argument, they are from Leibniz's Modadology which I happen to agree with:
  • Monad 31: Our reasoning is based upon two great principles: first, that of contradiction, by means of which we decide that to be false which involves contradiction and that to be true which contradicts or is opposed to the false.
  • Monad 32: And second, the principle of sufficient reason, in virtue of which we believe that no fact can be real or existing and no statement true unless it has a sufficient reason why it should be thus and not otherwise. Most frequently, however, these reasons cannot be known by us.
  • Monad 33: There are also two kinds of truths: those of reasoning and those of fact. The truths of reasoning are necessary, and their opposite is impossible. Those of fact, however, are contingent, and their opposite is possible. When a truth is necessary, the reason can be found by analysis in resolving it into simpler ideas and into simpler truths until we reach those which are primary.

The first part:
  1. You cannot think of absolutely nothing.
    • If you claim to be thinking of nothing, you are actually thinking of something. For example you may be thinking of blackness, this is something.
  2. If you think about the universe's non-existence, you are thinking about absolutely nothing
    • pretty straight forward IMO, if you have any issues, refer to point 1
  3. This is a contradiction, as you cannot think of absolutely nothing.
  4. Therefore the universe in general, must exist, necessarily.
    • The universes existence becomes a truth of reason by Monad 33, as the universe not existing is impossible to think of. And by Monad 31 the universe existing contingently is false.

Pretty solid, I asked by philosophy professor about this and he said this makes sense within this framework. He doesn't agree with this, but that is because he disagrees with these Monads.

Now as you imagine, this isn't that amazing, especially in the context of Leibniz as he says one can imagine an infinitude of universes.

I hold that our universe in particular exists necessarily. First off I do admit this is a bit on more shaky foundation. I could actually stop here and post, but I wanted to present my entire argument.

Also part 2 is not necessary for what I am saying later on about God, but I am posting it for completeness.

Part 2:
  1. When you imagine something, in your imagining, you are there in some way
    • This is an axiom I hold, but I want to you try to imagine being somewhere. Got it? Now where is your perception, its in that place.
  2. If you imagine a different universe, you do not exist there
    • You may have some other version of you there, but that person is not you
  3. You cannot imagine your own non-existence
    • Try to imagine not having a perception... yeah its not happening.
    • Its a contradiction to do this, so Monad 31
  4. Therefore it is impossible to truly imagine a different universe
    • Basically if you are truly imagine another universe, your perception cannot be there, as you do not exist there in any form by definition, the universe is different.
    • A retort can be made that you can imagine your death or before you were born, but again, you have perception there imagining all this.
    • Again Monad 31
  5. Our universe then must exist necessarily.
    • Much like my earlier argument, our universe's existence becomes a truth of reason by Monad 33, as thinking of other universes is impossible. And by Monad 31 our universe existing contingently is false.

Again, this is on much shakier ground, a few things here are a bit odd I admit, but I do think its follows.
I am still not sure if all this implies that other universes don't exist, just that we can't think about them truly.

Why does this Matter?

It all circles back to Monad 32, the principle of sufficient reason, that being that the universe must have a cause. This lies upon the assumption the universe is contingent, which I argue that is is not.

As far as God proofs go, the principle of sufficient reason is arguably the strongest card theists have, the only thing we can reply is that the universe may be eternal or that we do not know. This is important outside of Leibniz's Monadology, but for theological arguments in general: there basis is that the universe is contingent.

I disagree, with the above argument.