NEO-LEIBNIZIAN COSMOLOGICAL ARGUMENT
OBJECTIONS TO PREMISES 2 & 3
Recall premises 2 and 3:
2) If the universe’s existence possibly has an explanation, this explanation is an external one, since the universe is not a necessity.
3) The universe exists, and its existence possibly has an explanation.
For a defence of these premises, see the main post.
Here, the objections to these 2 premises are discussed.
FALLACY OF COMPOSITION
The concept that the universe could have been different simply because things inside the universe can change, is the fallacy of composition: things inside the universe can change without the universe as a whole changing.
That is correct, such reasoning would indeed be a fallacy, but that reasoning is not used in this argument. Instead, the universe as a whole could have been entirely different. For example, our current universe is as a whole very different from a universe that in total only consists of a single particle. Such a universe could have existed as it is not illogical. And such a universe is as a whole different from our current universe, not just in part, but in totality.
NECESSARY MULTI-VERSE HYPOTHESIS
What if it is logically necessary that a multi-verse with every single possible world exist? Up until now, no one (as far as I know) has been able to give a proper justification that it is logically necessary for a multi-verse with every single possible world to exist. In fact, it is highly doubtful if this is the case in reality. And if it’s not the case in reality, it definitely is not a logical necessity (obviously).
GOD COULD BE CONTINGENT
You can also apply these premises to GOD. I can conceive of GOD having slightly different properties, therefore GOD is contingent. This is objection is simply shifting the cause of the universe one step further. GOD is by definition non-contingent. Therefore, if you think that the universe was created by a contingent being (mistakenly called “GOD”), whatever created that prior contingent being is truly GOD. Otherwise one ends up with an infinite regress of contingent entities each creating the next one. Since an actual infinity cannot be truly reached, one would never have reached the entity that explains the existence of the universe. Thus, whatever explains the existence of the universe is non-contingent.
THE ARGUMENT DOES NOT SPECIFY WHAT KIND OF EXPLANATION IS NEEDED, THEREFORE THE ARGUMENT IS WRONG
It is true that the argument is open to any kind of true explanation for the existence of the universe, but that does not make the argument false in any way. To use a simple example, suppose one asks "why is this species of frog green?". One could respond in a number of different ways:
> That frog is green because that helps the frog camouflage among the green leaves and plants.
> That frog is green because the molecular structure of the frog's pigment absorbs photons of most wavelengths, but the photons whose wavelength most of our brains interpret as "green" are reflected away from the frog and those photons at that wavelength enter our eyes and thus we observe the frog to be green.
> That frog is green because natural selection working on random mutation has selected those green frogs as they apparently have a greater survival that the frogs which weren't green.
Notice all of these explanations are different explanations, yet all of them are of interest to biologists. If the questioner is willing to accept any of these 3 questions, does that make the questioner's question "incorrect"? Of course not! Similarly, the NLCA is flexible enough to allow any true explanation. But a (formal-)scientifically acceptable explanation for the existence of the universe is demanded nonetheless.
EVERYTHING FROM FORMAL TRUTHS TO EMPIRICAL TRUTHS CAN BE EXPLAINED, BUT AN EXCEPTION MUST BE MADE WHENEVER GOD COMES INTO PLAY
This is a highly obvious and very extreme attempt at special pleading.