I tried to find some really old posts I made on beliefnet back in the day, and I found this thread: "The use of reason in religion" on the UU section of beliefnet. This was one of my earliest attempts to defend the premise that God is necessary for objective morality, going all the way back to 2001. My thoughts really haven't changed on the subject, although I might present the arguments a little differently. Anyway, this begins on post 25, and later in the thread I get into a debate over it with somebody named ksagnostic. Here it is:
I really don't know how to approach this situation or even if I should. I'm afraid that in my effort to explain myself, I'll end up saying even more things that will need explanation. I'm not even sure what it is you're not seeing. I'm going to try, though.
First, what is the difference between saying, "If God does not exist, objective moral values do not exist," and saying, "If we don't believe God exists, objective moral values do not exist"? The difference lies in the fact that it's possible to believe something and be wrong. It's possible to believe God exists and yet God does not exist, and it's possible to believe God does not exist, and yet God exists. So if God and objective moral values exist, a person who does not believe in God can believe in objective moral values and be right. What I am saying is that it is possible to believe in objective moral values and to actually be moral without believing in God, but it is not possible to be moral if God does not exist because if God does not exist, then there are no objective moral values. If there are no objective moral values, then nobody is moral. I am not claiming that God's existence creates a moral authority. I am claiming that for objective moral values to exist, God's existence is necessary, but not necessarily sufficient. It's possible for God to exist and yet there are no objective moral values, but it's not possible for objective moral values to exist and yet there is no God.
I think if I explain what I mean by objective moral values, it should answer some of your other questions. In general, an objective truth claim is a claim about the object, and a subjective truth claim is a claim about the subject. I have a little thumb rule to help me tell the difference between a subjective truth claim and an objective truth claim.
If two statements that contradict each other can both be true, then the statements are subjective. If two statements that contradict each other cannot both be true, then the statements is objective.
Lemme give some examples. Take the two statements, "Ice cream tastes good," and "Ice cream tastes bad." These two statements contradict each other, but they can nevertheless both be true. Why? Because one statement is made by a person who likes ice cream, and the other statement is made about a person who does not like ice cream. Furthermore, the statements are not about the ice cream; the statements are about the tastes of the people making the claims. When a person says, "Ice cream tastes good," he's saying that he likes the way ice cream tastes. It's a subjective statement. The person making the claim is the subject, and the ice cream is the object.
Now take another two statements, "Blue Bell makes ice cream," and "Blue Bell does not make ice cream." These two statements are objective because they cannot both be true. No matter who makes the statements, they cannot be true because they are about the object, Blue Bell, and not the subjects making the claims.
Another test you can use to figure out whether a statement is objective or subjective is by asking whether or not it's possible for the statement to be false. You see, subjective statements can never be false; only objective statements can. That's why we think it's silly for people to argue over whether or not ice cream tastes good. There's no objective truth to it. One person likes it and the other doesn't. But it makes perfectly good sense for two people to argue over whether or not Blue Bell makes ice cream. Any argument two people have presupposes that there is some objective truth to the matter because if there is not, then the argument is pointless and silly.
So you see, claiming that people disagree on their moral views does not prove that there is no objective truth to the matter. In fact, it would be pointless for people to argue over a moral issue unless both parties agree that there is some objective truth to the matter. You can test yourself to see whether or not you think morality is objective or subjective by picking some moral position you feel very strong about and asking yourself if those who disagree with you are wrong. If you say they are wrong, then you believe in objective moral value. If all you can say is that they are different, but not wrong, then you probably do not believe in objective moral value. Furthermore, take whatever that moral position of yours is and ask yourself if it's possible for you to say, "A is right," and another person say, "A is wrong," and yet neither of you is incorrect. If you say that you cannot both be right, then you believe in objective moral value. If you say that you can both be right, then you do not believe in objective moral value.
Take rape for example. If I say "rape is wrong," and another person says, "rape is right," is it possible that neither of us is wrong? Is the statement about the act of rape, or is the statement about our personal preferences? If you say it's about rape, then you're a moral objectivist. If you say it's about our personal preferences, then you're a moral relativist. If it's about rape, then they cannot both be true. If it's about personal preferences, then they can both be true for the people making the claims.
I totally agree that if God doesn't exist, societies and individuals can nevertheless form moral standards to live by, but those moral standards would not be objective. You claim that societies and cultures determine right from wrong, which is a statement of moral relativism some call "society says" relativism.
Here's a question to consider, though: If societies set moral standards, what if two societies have moral standards that contradict one another? For example, what if one society says rape is right and the other society says rape is wrong? Can they both be right? If one of them is wrong, then there is some objective truth to the matter, and it is not determined by the beliefs of either society. That's the nature of objective truth claims. They are not determined by our beliefs because it's possible for us to believe things that aren't true.
If you believe the moral set by society are objective, then how do you deal with the fact that different societies contradict one another in their moral truth claims? More basic than that, though, what determines what the moral law of the society is? Does it depend on some guru the society invests with authority to make moral claims? What if some people in the society disagree? Are they wrong or just different? Does the majority rule?
Another thing to consider is that if the morals of societies are objective, that means moral revolutionaries, people we have historically considered heroes, are actually immoral people. Everybody who has tried to put an end to the values of their society were immoral people because they went against the morals of their society. That includes people like Martin Luther King Jr. It includes abolitionists. That's another thing to consider. Almost every society in history has had some form of slavery. Do we say they were wrong or just different?
If "society says" relativism is true, then there's no moral principle that transcends cultures, and therefore, there's no basis upon which to condemn moral atrocities in other societies. That was the argument the nazi's used during the Nuremberg trials. They were acting in accordance with the morals of their society. But you see, even they were inconsistent, because while claiming moral relativism, they were at the same time saying that those who were judging them were wrong. Moral relativists are often inconsistent. They'll say something like, "Stop pushing your morals on me," and you might ask, "Why?" Then they'll say, "Because everybody defines morality for themselves, so it's wrong for you to push your morals on other people." But do you see the contradiction there? First the person says that everybody defines morality for themselves, but in the same breath they claim it's wrong for one person to push their morality on somebody else, and they mean it's objectively wrong. You might want to respond with, "If it's wrong for one person to push their morality on somebody else, then why are you pushing that moral view of yours on me?" You see, the person who claims that morals are relative is trying to push their moral on the other person that it's wrong to push morals on other people. So it's almost impossible for moral relativists to live consistently with their views. That's why I really doubt that most people who claim moral relativism really are moral relativists. I think almost all people believe in objective moral values. It's just a matter of finding something they feel strongly about. That's why I asked you to think of something you feel strongly about - especially something you get emotional about. Then consider those who disagree with you and ask yourself if those people are wrong or merely different.
So if objective moral values exist, in other words if statements like, "rape is wrong," are objectively true, and if they are true even though some think they are false, then why is God's existence necessary? Why is it necessary for God to exist in order for objective moral values to exist? Why is it that if God does not exist, that objective moral values do not exist? This is one of those things that seems intuitively obvious to me, but is nevertheless hard to explain. It's like trying to prove that the law of non-contradiction is true. It's perfectly obvious and easy to see, but it's hard to make it clear to somebody else who doesn't see it. Having heard my explanation of what it means for moral values to be objectively true, you may already see it, but I'm going to try to explain it anyway.
A moral law is prescriptive. Rather than describing what is the case, moral laws prescribe what ought to be the case. They are imperatives that are in the form of a command. To say that something is right is to say that you ought to do it. You have an obligation or duty to do it. Feed your children. Likewise, to say it is wrong is to say that you ought not do it. You have an obligation or duty not to do it. Don't drown your children.
Whenever people have a moral disagreement with one another where each thinks the other has a moral obligation to behave in a particular way, there's a tendency for them to respond with the question, "Sez who?" This is a legitimate question. It's a challenge. The person asking the question is challenging the other person on their authority to make moral imperatives. He's saying, "Who are you to tell me what to do?" I think this challenge betrays an understanding on the part of the person making the challenge that without a legitimate authority there simply is no moral imperative. We're free to live autonomously. If no one "sez," then we have no moral obligation.
Morals have oughtness. Only persons impose duty and obligation on other persons, so there must be a personal being over us. Otherwise, there are no objective moral values. Without God, we are left with nihilism or relativism, both of which are forms of moral non-realism.
Moral oughtness implies purpose. There is a goal to which we are obligated to aspire, so our lives have purpose. The purpose of our lives is (at least in part) to obey moral imperatives. But for there to be purpose to our lives, there must be a personal being whose purpose it is for us to obey the moral laws.
But what kind of authority would be required for an imperative to be morally binding on us? Obviously, this authority must be higher than the government because we all have, at one point or another, a disagreement with what the law sez. We all think the law is wrong at some point. But the law can't be wrong if the government is a legitimate authority for deciding right and wrong. They would, by definition, always be right. So we see that things are not morally wrong simply because they are illegal, and they are not morally right simply because they are legal. If that were the case, then we'd all be immoral to ever try to change the law. Therefore, if there is an objective moral law, there must be a moral lawgiver whose authority is higher than that of any human government.
To say that something has meaning, value, or worth is to say that it means something to somebody, is valued by somebody, and that it's worth something to somebody. If there is no God, then whatever meaning and value we attribute to life is only relative. It only has meaning and value to us, but it has no objective or intrinsic meaning and value. Only persons ascribe meaning, value, and worth, so if people have intrinsic value and worth (meaning that we'd have value and worth whether other people cared about us or not and whether we cared about ourselves or not), then there must be a necessary transcendent personal being who invests us with value and worth.