I am moving on to Craig's sixth chapter and skipping the fifth. I am doing this because the fifth chapter is on the "fine tuning" argument, which focuses on an accumulation of evidence rather than if/then proofs. While I think the fine tuning argument is important, and it is good for Craig's flow as he steps us closer and closer to the Christian God, I want to save this argument for later. With that being said, I am moving on to Craig's sixth chapter, which zooms us in to the moral argument.
Before getting into the argument proper, it would be good to understand what we mean by objective moral values and duties. By objective, Craig simply means morals that are independent of people's opinions. Rape and murder are two great examples to highlight this distinction, since almost everyone would agree that these things are objectively wrong, regardless of changing times or cultures. If rape and murder are objectively wrong, then regardless of what society one is in, they would remain wrong. If morals were not objective, we could potentially find a time and place where either of these actions could be deemed permissible, or even good.
Craig argues that there are only four major options available to explain morality - only one of which brings us to an objective morality. The other three result in a subjective morality. Morality is 1) a social convention, 2) a personal preference, 3) a result of evolution, or 4) a result of God's existence. Craig believes that the only option on the list which provides for objective morals is number four. The rest would only produce a subjective, changing morality. Therefore, Craig puts forth his moral argument for God's existence as follows -
1. If God does not exist, objective moral values and duties do not exist.
2. Objective moral values and duties do exist.
3. Therefore, God exists.
Once again, we are left with an airtight argument. If premises one and two are true, premise three must follow. So let's go ahead and look at objections to the premises.
While most atheists fall into the camp of materialism (only matter exists), there are some atheists who believe in the immaterial (e.g. abstract objects), though not the supernatural. The materialists tend to argue that morals stem from physical or material happenings. They are the firing of certain synapses in creatures as a result of evolution, or they are the outworking of evolutionarily beneficial social elements incorporated into a community. Morals are not matter, but rather the actions of different conglomerations of matter. In essence, morals are just part of the physics of matter, or the properties of matter. The immaterialist, on the other hand, would argue that morals exist as abstract objects - features of the universe akin to the laws of physics. While we may be able to explain what happens with gravity, the "why" is a parameter that is built into the universe. Likewise, morals are something we can explain as observations, but their properties and parameters are "laws" of sorts that just are the way they are.
The problem both forms of atheism run into is that neither can explain moral values and duties in an objective sense. The materialist may be able to explain what he or she observes creatures performing a particular action, but the most that can be done is to provide a description. Likewise, the immaterialist can only claim that abstract objects such as truth and justice exist as features of the universe. The atheist can say that when someone murders, the community responds with force and/or by taking the murderer's freedom. The atheist can even explain how a community comes to act that way. They do it because it increases their chances of survival, it discourages others from murdering, etc. What the atheist cannot do is argue that it should be this way. The atheist cannot offer the prescription that says morality should look like X. Can an atheist say that the universe should produce gravity with different parameters? An atheist saying that we should all avoid murder is like an atheist saying we should all become as fat as we can. We might ask "why?" to both of those scenarios. In the first, the atheist may say "because it increases the survival and pleasure of the greater number of people - it increases morality." In the second, the atheist may say "because it increases the attraction between you and other objects, it increases gravity." No creature in the universe, given atheism, can act outside of the parameters built into the universe. Everything is natural and everything is neutral. No state of matter or non-matter is better than another. Having more gravity and having more morality is of the same type of thing. So how can any form of atheism prescribe what should be when everything is as it should be - given either a deterministic or random universe? Craig argues that they can't do so objectively.
Only theism provides a basis for objective morality and prescription. Only a universe infused with intent can provide the basis for morality. Morality as we understand it to be is not a description of how we do act or will act, but how we ought to act. "Oughts" can only come in relationship to another. They are obligations. We do not have obligations to matter, but to persons. On atheism, persons are not beings infused with objective morals and value. They are simply matter. How can one have an obligation to a form of matter that fabricates its own version of morality? And if we do have obligations to each other on atheism, and our systems of morality clash, whose morality trumps whose? And above all, how can we call something "wrong" that is simply the playing out of nature's parameters and laws? Nothing can be unnatural or wrong in a naturalistic universe.
Craig goes into much more detail as to the moral grounding problem faced by particular forms of atheism, as well as rebutting some common objections to theism, such as "Euthyphro's Dilemma." It is worth reading, but beyond the scope of the synopsis I'm intending to write here. However, I strongly recommend checking out some of Lewis's work represented in the fantastic videos below. They help to explain some of the reasoning behind needing God for moral grounding.
If one ends up throwing off premise one, they have a very difficult time explaining how morality is grounded. The only options that remain are blind forces, features of the universe that don't limit immorality, morally neutral and impersonal forces, or descriptive actions of particular conglomerations of matter (human society and actions). Deriving "oughts" and obligations from such things seems impossible, and arguing that some ideal of morality truly does exist when immorality is obviously a natural component of our universe - all seems so patently untrue and easily falsifiable.
Defense of Premise 2: Objective moral values and duties do exist.
There are very few people alive today who disagree that there are objective moral values. Many may say they disagree, but when pushed to it, their actions wholeheartedly agree with objective morality. Tell the father of a girl that rape isn't wrong, he will likely disagree. Tell someone that slavery or the holocaust were acceptable, or could be acceptable in the future, and most will disagree. Tell a relativist that they're wrong, and they will prove that they aren't really relativistic in the morality when they tell you that you are morally wrong for judging them. Almost everyone can be proven wrong if they say they disagree with objective morality. Objective morals are so intuitive to humans. Just as we have no reason to lack trust in our five senses to accurately convey to us physical information about the outside world, so we have no reason to distrust the ubiquitous moral intuition almost every human shares. The burden of proof seems to lie on the one arguing against the existence of objective moral values and duties.
In order to undercut premise two, the main route taken by atheists is to argue that since evolution is true, then morals are simply sociobiologically obtained. But Craig is willing to give atheists their assumption about the sociobiological evolution of morality. He says that "the sociobiological account at best proves that our perception of moral values and duties has evolved. But if moral values are gradually discovered, not invented, then our gradual and fallible perception of those values no more undermines their objective reality than our gradual, fallible perception of the physical world undermines its objective reality." While that sort of grounding doesn't necessarily make a belief untrue, it does serve to undercut the level of justification we have in a particular belief. Just as a fortune cookie could end up telling us something that's true, there would not be a good basis to believe it was true, or that it would make a good argument to use when persuading others about its truth. In essence, atheists seem to corner theists on this by saying that even if theists were right about morality, evolution means they have no basis to argue such.
Craig fires back with two very important points. First, he argues that the atheist's line of reasoning here is going in with the assumption that atheism is true. Given atheism, of course evolution would be a terrible reason for believing our moral intuitions. But given a God, even if evolution is true, there is no reason to think that a gradual growth of perceiving and understanding moral truths undermines those intuitions. It makes absolute sense that a moral God could and would plan for moral creatures to perceive morality with a certain degree of accuracy. Just as optical illusions don't show us that our vision should be largely discounted, so moral myopia doesn't mean our grasp of morality is generally untrustworthy.