What is meant by necessarily, is not what has to be in one world or this world, it is what is necessary in all possible worlds ontologically.
So for example, if God was necessary in this world as the first cause, but there can be another possible world, where he is not the first cause, then cosmological first cause view point would not prove that it's possibly necessarily.
To be possibly necessarily, it's stating it's possible that all ontological possible worlds, need a necessary living being.
This can't be things that can be different by definition of what they are, because, then we can create different possible worlds. For example, this necessary living being, cannot have a colour. If it had a colour, then it can have a different colour in a different possible world, and hence it would not be the necessary being in all possible worlds.
But if it's properties are by logical necessity, like 1 + 1 = 2 in all possible worlds, then it's possibly the necessary being.
So for example, if God was necessary in this world as the first cause, but there can be another possible world, where he is not the first cause, then cosmological first cause view point would not prove that it's possibly necessarily.
To be possibly necessarily, it's stating it's possible that all ontological possible worlds, need a necessary living being.
This can't be things that can be different by definition of what they are, because, then we can create different possible worlds. For example, this necessary living being, cannot have a colour. If it had a colour, then it can have a different colour in a different possible world, and hence it would not be the necessary being in all possible worlds.
But if it's properties are by logical necessity, like 1 + 1 = 2 in all possible worlds, then it's possibly the necessary being.
