Update 1/30: Expanded on some things
The Moral Argument
I don’t like the traditional version of this argument that argues from the moral law to a moral law-giver:
Traditional Argument from Morality
Premise 1: There is an objective moral law.
Premise 2: Every law implies a law-giver.
Conclusion: Therefore, there is a moral law-giver.
Premise 2: Every law implies a law-giver.
Conclusion: Therefore, there is a moral law-giver.
The most important problem with this argument is, if God is not just making stuff up, then he is the goodness described by the moral law, which means he is “that to which the moral law corresponds” or “that which the moral law describes”. So, you could rephrase the argument this way:
Premise 1: There is “that which the moral law describes”.
Premise 2: Every law implies a law-giver.
Conclusion: Therefore, there is a “that which the moral law describes”-giver.
Premise 2: Every law implies a law-giver.
Conclusion: Therefore, there is a “that which the moral law describes”-giver.
In other words, this argument concludes that God is making himself up.
First, to prevent this argument from saying that God is just making stuff (or himself) up, we need to end up concluding that God commands the law in accordance with his good nature. When he commands, he does not give something new (new to us perhaps, but not new to him)—he gives something that corresponds to his eternally good nature.
Second, to prevent this argument from scaring away the nihilists and logicians, we need to start out referring to our hunger for true goodness, rather than simply assuming the moral law (or “that which the moral law describes”) exists in the first premise—we are supposed to be arguing “to” that conclusion, not assuming it in the premise.
“A man’s physical hunger does not prove that the man will get any bread; he may die of starvation on a raft in the Atlantic. But surely a man’s hunger does prove that he comes of a race which repairs its body by eating and inhabits a world where eatable substances exist. In the same way…my desire for Paradise…is a pretty good indication that such a thing exists.” — C.S. Lewis, The Weight of Glory
The same is true regarding moral hunger. The fact that the Golden Rule is found in every major culture in history is evidence of our universal hunger for true meaning and goodness, which is evidence that there is something in reality that will fulfill our hunger. Even nihilists show this hunger when they refuse to allow constructs to obligate them.
Revised Argument from Morality
Premise 1: We all hunger for true goodness and meaning.
Premise 2: We would not all have this hunger if there were no true goodness or meaning to satisfy our hunger.
Conclusion: Therefore, there exists a being to which true goodness and meaning corresponds.
Premise 2: We would not all have this hunger if there were no true goodness or meaning to satisfy our hunger.
Conclusion: Therefore, there exists a being to which true goodness and meaning corresponds.
How this relates to law, in contrast to the “Moral Law-Giver” argument, is that only laws (God-given, or man-given) which correspond to this good being obligate us, as these are the only laws which satisfy our hunger for true goodness and meaning.
I also like this version of the argument much better because it does not tangle obligation up with fear, or the idea that we are merely obligated because “God said so”. He does not say so arbitrarily. His perfect, loving goodness is what ultimately satisfies us, and perfect love casts out fear (1 John 4:18).
This version does not conclude there are moral truths–only that “if” there are, there must also be a God to which they correspond:
Alternative Revised Argument from Morality
(in response to this argument)
P1: Beliefs, in order to be true, must correspond to reality.
P2: Moral beliefs, in order to be true (iow, in order to be moral facts), must correspond to a perfectly moral person.
C: Therefore, if there are true moral beliefs (iow, if there are moral facts), then a perfectly moral person exists to which moral facts are true.
P2: Moral beliefs, in order to be true (iow, in order to be moral facts), must correspond to a perfectly moral person.
C: Therefore, if there are true moral beliefs (iow, if there are moral facts), then a perfectly moral person exists to which moral facts are true.
Ichthus77 
Interesting restructuring of the Argument from Goodness, but it doesn't escape the two biggest problems with this “proof”:-
1) For “good” to have meaning, it must have an independent definition. If it does, then the definition can exist without God. If goodness *doesn't* have an independent definition, but instead means “whatever God says it means”, then you have objective *amorality*. Not, I think, an improvement!
2) The initial proposition. Desire isn't actuality. We could all “hunger for” a winning lottery ticket: doesn't mean we're any likelier to get one. (Sadly.)
These are similar problems to those generally found in divine “proofs”: God isn't a logical puzzle to be solved. If you did manage to “prove” God, you'd be limiting him, and inadvertently diminishing him. God has far more power as a symbol than he does as the answer to a formula.
Hi Byron :)
“1) For “good” to have meaning, it must have an independent definition. If it does, then the definition can exist without God. If goodness *doesn't* have an independent definition, but instead means “whatever God says it means”, then you have objective *amorality*.”
An “independent” definition is a free-floating definition which attaches to nothing, “therefore is not a reality. Being a dependent definition makes it a reality. An independent definition is immoral because it is a lie,” (my son Ethan). You are right that if it is about “God says so” then it is about God making up a definition (which, btw, would be ‘independent’), however—I already noted in the original post that whatever God says about goodness is in accordance with (is dependent on) his good nature. As for the definition of goodness, I have discussed ‘that’ whenever I talk about the Golden Rule elsewhere. However, if there is no God, the Golden Rule is not “really” good (there is nothing to which it can correspond). That we hunger for it is a clue to God’s existence (and the Golden Rule’s correspondence/dependence). I don’t know about you, but I think it’s cool that even when God ‘tries’ to make stuff up—the universe happens.
“2) The initial proposition. Desire isn't actuality. We could all “hunger for” a winning lottery ticket: doesn't mean we're any likelier to get one. (Sadly.)”
You are right that desire isn’t actuality. But, we’re not talking about winning lottery tickets, for which not everyone hungers – we are talking about true goodness – for which everyone hungers. You don’t even challenge that…you grant it. I will grant that being hungry for food doesn’t mean we will get any food—however, that we ‘do’ hunger for it is evidence for the existence of food (long enough to have evolved a hunger for it). Thirst is evidence for the existence of water. Weariness is evidence for the reality that we sleep. And so on.
“These are similar problems to those generally found in divine “proofs”: God isn't a logical puzzle to be solved. If you did manage to “prove” God, you'd be limiting him, and inadvertently diminishing him. God has far more power as a symbol than he does as the answer to a formula.”
I don’t consider this a ‘proof’. I don’t think anything can be proved w/ certainty. It is just one of many clues in a cumulative case. How does there being clues to his existence, limit him? Having power as a symbol is only ‘good’ if the symbol points to something real—and only if that ‘something’ is genuinely good. And why settle for the symbol when you can have that to which it points? That for which we all hunger. That which ultimately satisfies.
By “independent” I mean “independent of God”.
Your son's of course right to say that a definition is dependent on something: its content. If that content can be understood in a self-contained way — as with the Golden Rule — and its merits are inherent to the proposition, argued without reference to its creator, all God would add is authority. This is the authority fallacy, and takes us right back to “good is what I say is good”.
Does everyone “hunger” for goodness? I don't know. For the statement to be meaningful, there'd have to be a shared definition of goodness, that transcends all boundaries of time and culture. Even then, I don't see how you'd go about proving that everyone hungers after it. Weariness is indeed evidence that we need sleep. How does this analogy correspond to goodness?
Clues to God's existence wouldn't limit him in the way a proof would limit him, no. This opens a whole new question of why God values “the substance of things hoped for, the evidence of things not seen”.
As for getting past a symbol, that would in itself limit. A symbol points to something else: if we could comprehend the whole of God, then God has, ispo facto, been delineated. It makes God into another being, instead of being-itself.
Byron: “argued without reference to its creator, all God would add is authority. This is the authority fallacy, and takes us right back to 'good is what I say is good'”
God is not the 'creator' of good. He does not add authority. He “is” the good. Without him, “good” (the Golden Rule) refers to nothing. It describes him.
There is evidence of a hunger for true goodness in every major culture, as we find the Golden Rule in every major culture, and even in nihilists, who will not allow themselves to be obligated to constructs. But even if there was no agreed upon standard like the Golden Rule, it would not rule out there being a true standard, just as ignorance about nutrition says nothing about whether or not physical hunger is real, or whether or not there are healthy and unhealthy ways to eat.
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Niether proofs nor clues would limit God, and faith (trust) is never blind. The things hoped for…not seen…are fulfilled promises. We trust they will be fulfilled based on what God has already made evident about who he is and who we are in relation to him.