I remember as a child sitting next to my Grandma-Anna Maria Olinda Hussmann (formerly Reinkensmeyer.) She was eating split pea soup. I was four and fascinated by the lines in her hands.
"Grandma, why do you have so many lines on your hands?"
She touched my hair. "Well, honey, those are blood veins and the older I get, the more they show up."
"Blood veins? I thought blood was red. Why are they blue?"
"Blood is red when it's outside the body. Inside sometimes it's blue."
"Why is it blue?"
"Well ... it's blue until it touches oxygen. Then it turns red."
"Why?"
"It's how blood reacts to oxygen."
"But why?"
"Why don't you go in the other room and play with your cousins, sweetie?"
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We've all seen it. Kids can ask "why, why, why" till their faces turn blue.
Parents find themselves responding:
"Go look it up."
"Ask your mom."
Or, "because I said so."
A long line of "whys" illustrates a principle philosophers call an "infinite regress."
Skip this paragraph and move to the next if it's too much, but here's the definition of an infinite regress: An infinite regress in a series of propositions arises if the truth of proposition P1 requires the support of proposition P2, the truth of proposition P2 requires the support of proposition P3, ... , and the truth of proposition Pn-1 requires the support of proposition Pn and n approaches infinity.
Basically, when we ask "why" we look for a cause, and each cause needs further explanation.
"Why is the moon so bright if it provides no light?"
Be-CAUSE the light of the sun is reflected off the moon.
But, for every explanation, another question arises.
"Why does the sun provide light?"
Be-CAUSE the chemical reactions taking place emit radiation in wavelengths that can be perceived by the human eye.
"Why does the eye perceive those wavelengths?" or "Why do the chemicals react that way?"
And so on.
In a world of cause and effect (the foundational concept of science) every good solid answer brings up another "why."
And here's where God shows up.
The infinite regress cannot be actually infinite because an actual infinite is just a concept, not something real. Actual infinites don't exist.
William Lane Craig argues this with the following example:
Let's say, for kicks, that Jupiter revolves around the sun at half the speed of Saturn. Let's pretend a thousand years from now Saturn has completed 1000 circuits. How many has Jupiter completed? That's right-500.
In 10,000 years it's 10,000 for Saturn, 5,000 for Jupiter. In a hundred thousand ... you get the picture.
But what if we extend time into infinity. Then, all of a sudden Saturn has rotated an infinite amount of times. Right? Now, what about Jupiter? How many times has it revolved? Half of infinity? Infinity?
An actual infinite is impossible and there are many, many more examples that justify this belief.
What does this mean about God.
As I've mentioned before - the Universe (time, space, and matter) had a beginning. That's a pretty universally accepted truth in scientific circles today-and happens to be exactly what theists have been saying, well, from the beginning. And the CAUSE had to be outside of time, space, and matter. And because most atheists understand this truth, recent explanations (causes) have been theorized such as multi-verse theories, string theories, etc....
But even if true (though speculative now) they do nothing to explain the uncaused cause.
I know of no way to get around the philosophical truth that there MUST BE AT LEAST ONE UNCAUSED CAUSE.
If we ask why long enough, we always, always, always arrive at a determinate point in the past (though "past" may mean something different) where the answer really is, "IT just is." There's no escaping IT and I believe, on intellectual grounds, no denying IT.
The question then becomes, "What is IT?" Therein lies one of the greatest battlegrounds between atheists and theists. Theists say God. Atheists say matter.
But we've already established, matter had a beginning.
Couple that with other areas of thought including special revelation verified through history and archaeology, DNA studies, philosophy of morality, and a hundred other disciplines and I believe the answer is clear.
IT = God, a personal intellect that is omnipotent, moral, and personal.
But even if your agnostic and atheist friends don't arrive at the same conclusion, it's still a great discussion question:
"There has to be at least one uncaused cause. What is it?"
An atheist MUST say either, "I don't know" or "matter." But current science tells us matter is not a good option.
Theism offers the only good answer to the question "why?"
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For more reading on this and similar topics GO HERE.
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Also, if you haven't done so yet, please consider purchasing the Kindle version of my new book Letters From a Martyred Christian HERE. When you're done reading it, please post a review.
You're right that if we always expect every explanation to have an explanation then we necessarily end in an infinite regress. It's a strange but true (as far as I can tell anyway) fact. I believe that it is an issue left unresolved by simply defining God as outside space time (why not just define the universe itself as not needing an uncaused cause in the way you have done for God?) This seems like a problem everybody has, we can't wish it away with clever definitions.
Despite this, we can still have effective explanations for things. Effective explanations do not themselves require explanations, we have different, more effective criteria for determining a good explanation and having a further explanation is not one of them. Those criteria are:
1. Testability (not only testable in principle, but offering very specific predictions, i.e., it is more impressive to predict the day and size of a hurricane than to say a hurricane will occur within a span of 3 months)
2. Consistency with background knowledge (current established truths)
3. The success of the tradition from which the explanation comes (track record matters)
4. Simplicity
5. Explanatory Scope (Does it explain things the previous theory didn't?)
6. Fruitfulness (Does it lead to more areas for research?)
7. There may be others, I'm not sure.
You say, other lines of evidence "including special revelation verified through history and archaeology, DNA studies, philosophy of morality, and a hundred other disciplines and I believe the answer is clear."
Of course, I think theism fails every one of these tests, and that is why it is not the best explanation. We live on an indifferent planet where the half-hazard fumbling of evolution has produced creatures "good enough" to survive up to this point. That's the clearest, most consistent, most empirically justified explanation.
Great post, H.
Ab3: A couple brief thoughts on your comment:
God being outside spacetime isn't really relevant to the question of whether or not he can stop an explanatory regress. In fact, the question of how to understand God's relation to spacetime is controversial, but there are those on all sides of that question who would agree that God is the uncaused cause that ultimately grounds not only being, but knowledge as well. Also, the reason we can't just "define the universe itself as not needing an uncaused cause" is clear in HL's post: we know that the universe had a beginning, and our accumulated experience tells us that things that begin to exist have causes. In order to do what you suggest, we must abandon the latter notion, which in addition to being a bit ad hoc, leaves us in the awkward position of admitting that things (even potentially infinite things) can and do just pop into being, completely uncaused and without explanation. I fail to see how this is a better explanation than the one theism offers, especially when objections to philosophical naturalism are considered (particularly that is self-defeating in that it undermines knowledge and rationality, including any reasons one might have for believing in naturalism).
Also, I should probably note that cosmological arguments should be distinguished between the explanatory variety (like what this post is mostly about), and the causal variety. For more on this, see here: http://robertwhitaker.blogspot.com/search/label/cosmological%20argument
More interestingly, why is God required for existence and knowledge? What is the basis of this? To my eye, Evolution as an extension of Naturalism explains knowledge in a logically and empirically consistent manner. We would have had to be good at building models of our world to survive, but evolution also explains why we so often make mistakes when doing so. How does a theist explain why our memory is so bad and our reasoning so often flawed? We can demonstrate consistent failures in human reasoning, why would God have made us this way?
Also, if you just require that in order to exist or think, then you must have a supernatural being acting as the ground for being and thinking, then again, you have only begged the question. Could I refute you by creating a God of Evolution?
Ab3: Your question is an involved one, so I will not attempt to answer it here, but merely punt to a better source. I recommend the recent work of Alvin Plantinga for the relationship between science and theism, particularly the issue of what, if any, relevance evolutionary theory may have for the Christian worldview. I'll say only that most thoughtful commentators on this subject agree that the relevance is minimal. Evolution is not an 'extension of Naturalism,' as you say, but a separate philosophical assumption. Neither entails the other. For why naturalism fails to ground knowledge, see especially Plantinga's "Evolutionary Argument Against Naturalism," in which he assumes the truth of evolutionary theory and argues from this that Naturalism is an irrational position. God, on the other hand, provides a much more satisfactory explanation of both knowledge and existence (particularly the latter), as He is the least arbitrary stopping point in the causal/explanatory chain. No question begging there.