K.O.S, in modal logic, there are possibility, existence and necessity. A sentence is logically possible when its contradictory is not self-contradictory. This being so, your flying spaghetti monster is logically possible.
But we have to make a distinction between logical possibility and real or objective possibility (that is Kant, btw). A sentence is really possible when its object can be connected with other phenomena in time and space. In this sense, a flying spaghetti monster is not possible, because the idea of flying spaghetti is opposite to what we know about other flying objects.
No, existence that we can know about is existence in a physical world. since the physical world is the only world that you can know, you think you can reach the conclusion that it is the only existent world. that is not logical, my friend.
I agree with you, but what counts as nature can change. We know for sure it will be something connected with time and space (therefore, it won't be God or cartesian soul). But what are all the types of phenomena in time and space? you don't know that. maybe my so called soul is an energy that will survive in nature beyond my body. I don't know it by now. but even if Descartes is right and my soul is supernatural, it doesn't mean it doesn't exist, but only that I cannot know if it exists or not.
wrong. logically, it is possible an existence beyond matter and energy. it is just incognoscible (i hope it's a word in english).
I agree with your criteria, but I'm not so sure as you about the application. even mathematical paradigms have changed. what if a new paradigm can make those so called supernatural phenomena measurable? that is not impossible, because they are supposed to be temporal (maybe even spatial). do you get me?
to sum up, I disagree with you in two levels: 1) incognoscible (a word in english or not lol) is not the same as non-existent, 2) I'm not sure if a certain type of phenomena called supernatural nowadays will be incognoscible and, therefore, supernatural forever.
anyway, I see you are an educated person and I liked to talk to you