As part of his response to cosmological arguments for the existence of God, Philosopher JL Mackie posed a question for theists in his book The Miracle of Theism: Arguments For and Against the Existence of God:
There is a priori no good reason why a sheer organisation of things, not determined by anything, should be unacceptable, whereas the existence of a God with the power to create something out of nothing is acceptable': How is the explanation that there is no explanation as to why an organisation of things exists any less logical than the existence of a deity? - MackieTo which Victor Reppert makes this devastating comeback:
I usually reply to this with my bunny rabbit argument. Suppose you and I are eating lunch. You look away, and then, you notice a bunny rabbit is munching on your salad. You ask me how it got there, and I reply, that, funny thing, it just popped into existence without a cause. Would you take that seriously? - Reppert
How ridiculous is it to think that something can just pop into existence for no reason? We have this philosophical principle known as the Principle of Sufficient Reason (PSR) that tells us that it would impossible for any such thing to happen, and theists cling to it like their life depends on it. The PSR tells us that everything has a reason or explanation, which is equivalent to saying everything has a cause for its being. Well, almost everything. According to theists there's one thing that has no cause for its being, and that's the thing that is the cause for all other things - namely God. God has no cause because he is supposedly eternal. He has no beginning, and therefore he has no cause. But if you want to make this fit with the PSR, you can simply say that God does have an "explanation". God is his own explanation. For everything else, its explanation is its cause, which is ultimately God. As far as the theist is concerned, the PSR holds, and all is right with the world.
But as we can see, if you are a theist, and you want to defend the PSR, you are forced to engage in special pleading, whereby you carve out one single exception to the rule. Everything has a cause, but God doesn't. God doesn't need a cause, because he's special. But nothing else is. And everybody knows that bunny rabbits are not special. They need a cause. They don't just pop into existence for no reason. How ridiculous. Does it seem strange that a philosopher like Victor Reppert would use special pleading and ridicule to address the quite serious question of another (and far more accomplished) philosopher? It seems strange to me. But of course, we're talking about defending theism, which is based on unsound logic to begin with, so why not try to turn the tables by employing still more bad logic?
Victor, like most theists, refuses to acknowledge even the possibility that there could be something aside from God that exists without a cause. This has always puzzled me. It seems plainly obvious that there is at least the logical possibility of uncaused things. All things can be classified into two categories: things that are caused, and things that are not caused. What kind of things might not be caused? Logically, there could be two categories of uncaused things: things that have no beginning in time, and things that do have a beginning in time. Let us examine both of these logical possibilities.
The first - things that have no beginning in time - would include God (remember, we are talking about logical possibilities, not what actually exists). It would also include anything else that has no beginning. Such things may be known as brute facts. They are things that simply exist, and their existence is eternal, so it is necessarily true that they have no cause, because a cause implies a beginning. For example, if there is some kind of eternal multiverse, and it spawns universes such as the one we inhabit. That could logically be the cause of our universe. One need not accept the actual existence of such a thing, but there is nothing illogical about accepting the possibility. In fact, it would be illogical to reject such a possibility. But that's what theists do. (See my earlier article on religionists' denial of brute facts.) In all my arguing with theists on this issue, I have yet to hear a cogent explanation as to why a brute fact (other than God) cannot possibly exist. And I don't think I ever will.
The other category of possible uncaused things is comprised of those things that exist with some beginning in time, but have no cause for their existence. Now, I recognize that human experience has traditionally told us that this never happens. And that's where we get our notion of the PSR. But reality is broader than human experience. And the truth is that with more advanced tools at our disposal in modern times, we are able to observe things that go far beyond what the naked eye can see. And we do see things that come into existence with no recognizable cause. They actually pop into existence where there was nothing before - no cause that we would see as either material or efficient. Welcome to the world of quantum mechanics. It's not only a logical possibility - it's a reality. And yet, theists still deny it. (See the scientifically ignorant ranting of this religionist, for example. And please note that even if one concedes that the quantum vacuum consists of something rather than nothing, they still can identify no specific cause for quantum events. Quantum events, including the spontaneous creation of virtual particles, just happen randomly.) Most theists simply deny even the possibility that there could be such a thing, despite what has been observed.
As for bunny rabbits, it does indeed sound absurd. Quantum events are observed to happen without cause, but bunnies are not quantum events. They don't just pop into existence, as far as we know. And that's what makes Victor's argument sound like a legitimate reductio ad absurdum. But what if we substituted quantum particles for the bunny in his retort to Mackey? It's not crazy. It happens all the time. Things do pop into existence. Is it something one could take seriously? I'd have to say, yes it is. And is Victor's argument something that one should take seriously? I'd have to say, no it isn't.
And besides, he didn't even answer Mackie's question.