Our last apologetic's topic focused on the first chapter of William Lane Craig's book, "On Guard," where he laid out how absurd and unlivable life would be if an atheist were to be logically consistent and live out the implications of their worldview. While that doesn't disprove atheism, it should at least produce an interest in individuals to seek out and weigh the merits of believing in a god/gods/God. In the next chapter, "Why Does Anything At All Exist?," Craig is going to move into positive arguments for God. Here, Craig assesses the very origins of the universe.
1. Everything that exists has an explanation of its existence [either in necessity of it's own nature, or an external cause].
2. If the universe has an explanation, that explanation is God.
3. The universe exists.
4. Since the universe exists, it must have an explanation of its existence.
5. That explanation is God.
The argument above is unarguably logically valid. IF the premises are true, the conclusion MUST be true. Obviously, atheists will not agree with the conclusion, so they must disarm the argument by disproving at least one of the premises 1-3. Therefore, Craig spends most of his chapter defending the premises.
What about God's explanation?: Most people - atheist and theist - misunderstand premise one. We all tend to think that an explanation must mean a physical sort of cause. However, the explanation of existence can also be grounded in a property of necessity. This simply means that an object or person had to exist. It could not be that the person or object would not exist. It is similar to numbers or colors. The number 2 (the actual number, not the visual or verbal representation) has a property as such that it always represents a very particular number. It can never really be 3 or 4 or anything else. Likewise, whatever has been here from eternity past - whether that's God or matter - must have the property of necessity. That is a valid explanation. Note how the Christian agrees that necessity could work for the atheist because matter could have this property.
While the naturalist has access to arguing the necessity of the universe, Craig notes that most atheists find this notion utterly absurd. They recognize that it just won't work for the universe. Why? Because the property of necessity requires that whatever holds this property, had to be as it is. Atheists recognize that there are a plethora of different possibilities for how the universe could have been, and they recognize that all we see could fail to exist. That truth precludes atheists from using the property of necessity as an explanation for the universe. However, it doesn't prevent a theist from using it for God. The question "where did God come from?," then, is absolutely irrelevant, as at least the Christian theist will argue the property of necessity - an argument that is also open to the materialist, should they believe they could defend it from the evidence we have of the universe.
The universe just exists inexplicably: Premise one is very intuitive to most people. Of course there must be an explanation for everything. However, if the atheist throws off arguing the necessity of the universe, they're stuck with saying that the universe just doesn't need an explanation. This seems either crazy, or an idea that stems from an ulterior motive. "Just because" isn't a very rational explanation, especially for a group that prides themselves on reason, science, causation, and answers. "Inexplicable" isn't an answer; it's a non-answer. Note that atheists are not saying "we just can't explain it yet," they're saying that the explanation IS "there is no explanation." Craig argues that if you found a strange object in the woods and your friend said "just move on, there's no reason for it being there," you'd either think your friend had an ulterior motive (he wanted to just keep hiking), or that he was very inaccurate. Of course there is a reason the object is there, whether that reason is a natural, inherent, or personal explanation. Regardless of how large or small an object is (marble sized, boulder sized, planet sized, or universe sized), everything requires an explanation.
Some atheists try to maneuver around an explanation by arguing that everything except the universe needs an explanation. But not only does this seem ad hoc and self-serving, it doesn't make sense to say that every component of the universe needs an explanation, but the universe itself does not. Craig expounds on this notion, and several others, much more in the chapter. If what I have said so far is not apparent, I recommend digging deeper into chapter 4 of his book.
Defending Premise 2: If the universe has an explanation, that explanation is God
When I first read Craig's argument, I thought premise two was a big leap. How in the world could you say that the explanation must be God? Well, because the atheist is absolutely trapped at this point. If an atheist denies premise one, they are saying that "the universe does not have an explanation." The existence of space, time, and matter are inexplicable in and of themselves. If this is their position, then if an explanation did exist, that explanation would be outside of space, time, and matter, and would therefore be gods/a god/God.
Defending Premise 3: The Universe Exists
If someone disagrees with premise three, they're either just being obstinate and combative and will not be able to hold a reasonable conversation, or their understanding of knowledge and truth is one that rational, scientific arguments will not affect them anyway. You would have to have a very different starting point for God. It's extremely rare that you'll find someone who legitimately holds this position.
In conclusion, then, the core of the argument for existence lies largely in premise one. Premise one seems impossible for the atheist to accept, knowing what we know about the universe and the possibility for all its variances. But if premise one is denied, atheists are left saying that the answer they have for origins is that there is no answer - meaning that if there were an answer, it would have to be beyond the universe. And since almost nobody will take on the argument that the universe doesn't exist, non-answers are the best an atheist can do. I'm not sure how they find that satisfying, knowing that all their endeavors for answers are grounded in a beginning that has none, and never will. But just as we saw with the absurdity of life without God, atheists must come to either accept the truth or live deluded of the implications in the fact that there are no answers and there is no reason for their lives. It doesn't seem a stretch at all, then, that they would accept the universe is "grounded" in the exact same type of disorder, randomness, and meaninglessness.
I had to read this chapter several times when I was first exposed to this argument. It takes awhile to wrap your mind around all the arguments and counterarguments. However, Craig does a great job of laying out the argument in a logical sequence and anticipates the reader's questions and push-back well. He also includes a good diagram at the end of the chapter that can assist in understanding the logical progression of the argument. It is a very difficult chapter to summarize here, as there is so much meat to the argument. I highly recommend taking a look at this one yourself.