(1) If god does not exist, then objective moral values and duties do not exist.
(2) Objective moral values and duties exist.
(3) Therefore god exists.
Now I believe that (1) is true of moral duties and not of moral values. I also believe that (2) is true of moral values but not of moral duties. So to be able to focus on each premise of contention without skipping around lacking organization, I will distinguish between moral argument A and moral argument B. I will discuss argument A first.
A1. If god does not exist, then objective moral values do not exist.
A2. Objective moral values exist.
A3. Therefore god exists.
Clearly in order to discuss and understand this argument we need to define what we mean by "objective moral values". By "objective" we certainly mean that something is true independent of any opinion. This metaphysical objectivity contrasts with epistemological objectivity in which we mean that an idea was formed in an unbiased manner. "Moral values" refers to whether or not some action, person, event, or thing is either good or evil. Therefore by "objective moral values" it is meant that some action, person, event, or thing is truly either good or evil independently of any opinion. This leaves us with the an obvious question though, what do we mean by "good" and "evil". Trying to define these terms generically always makes the definiendum simply a restatement of the definiens, such that it hasn't actually been explained what is meant by "good" and "evil". For instance Webster defines "good" as virtuous, right, or commendable, and "evil" as morally reprehensible. These are simply synonyms and don't actually explain what the word refers to. It is clear that in order to even discuss this argument we must provide explicit definitions of what we mean when we say that something is "good" or "evil". It is worth noting here that to debate moral ontology you must first discuss moral semantics, because it makes no sense to debate whether or not something has an actual metaphysical status unless you first know what you actually mean by that something that you are debating about.
Here now we come to an obvious true dichotomy, of the form A or not-A. Either you will:
(1) Define "good" and "evil" in such a way that god has to exist in order for them to exist.
(2) Define "good" and "evil" in such a way that god does not have to exist in order for them to exist.
If you do (1), then A2 becomes obviously question begging because the only reason you would have to accept the existence of objective moral values is if you already accept the existence of god. If you do (2) then A1 becomes obviously false, for (2) is the direct negation of A1. For example, if the theist defines "good" as "that which is in accordance with god's moral nature" and "evil" as "that which is contrary to god's moral nature" (as theists often do), then there could be no argument given to prove that things are really good or evil without presupposing the existence of god, for an atheist would hold that god's moral nature does not even exist. On the other hand the atheist often wants to define "good" as "that which contributes to the well-being of sentient creatures" and "evil" as "that which detracts from the well-being of sentient creatures". On this definition A1 is clearly false, for even if god does not exist there are still things that objectively contribute to or detract from the well-being of sentient creatures.
Since this is a true dichotomy, any and every given definition of "good" and "evil" that are provided will either make this argument question begging, or simply unsound. So it seems then that moral argument A will fail either way.
So what about moral argument B, that goes like this:
B1. If god does not exist, then objective moral duties do not exist.
B2. Objective moral duties exist.
B3. Therefore god exists.
This argument is more plausible that moral argument A but ultimately doesn't fair any better. We've already defined "objective" so for this argument all we need to define is "moral duties". A "moral duty" is something that you ought or ought not do. So then "objective moral duties" are actions that you ought or ought not do independently of any opinion. Unlike the existence of objective moral values, the existence of objective moral duties cannot be decided purely definitionally.
I agree with B1 on the basis that I would deny B2. I deny that objective moral duties exist and so I thereby agree that if god does not exist, then objective moral values do not exist. I would also affirm that if god exists, then objective moral values do not exist. Why? On the basis of Hume's Is-Ought problem. Hume observes that there is a difference between descriptive Is statements and prescriptive Ought statements. It seems that the only way to get to an Ought statement is by use of a subjective If clause, rather than an objective Is clause. For instance, imagine you are standing in front a brick wall. It would be correct to subjectively say, if I do not want to whack my head, then I ought not walk forward. But, it is not correct to say simply that there is a wall in front of me, therefore I objectively ought not walk forward. Why ought I not walk forward? It seems that if I did want to whack my head, then I ought walk forward, even though there is a wall in front of me. So I think that this gives us grounds for thinking that prescriptive Ought statements must be rooted in subjective desires rather than objective facts.
For those reasons I accept B1 and deny B2. However note that just because I already accept B1, that doesn't mean that you should just allow the theist to have B1 without holding up his burden of proof, for note that in order to prove B1 the theist would first of all have to adopt some form of the Is-Ought problem, and then not only that but also disprove every attempt that has been made to bridge the Is-Ought problem without the use of god, such as Kant's categorical imperative, Searlian style attempts, and egoistic attempts that have all been made to show that you can derive an objective prescription from purely descriptive objective statements. I also accept this as my burden of proof when giving a complete account of my acceptance of B1 and denial of B2, but to fully do that would be beyond the purview of this essay.
Now coming to B2 by itself I've already noted that I think that we have a positive objection against it in the form of Hume's Is-Ought problem, but to fully spell out that objection we would have to dispel every attempt to solve the Is-Ought problem, so let's instead turn to how the theist might argue for B2. It seems to me that, similarly to the problem with moral argument A, it is actually impossible to argue for B2 without either begging the question in B2 or disproving B1. For note what objective moral duties are, they are not some concrete, physical objects that we can simply empirically confirm the existence of, rather objective moral duties aren't entities at all. To say that objective moral duties exist is to say that some prescriptive proposition is true independent of any opinion (this is to assume a non-platonistic view of moral values and duties, however even on platonism you cannot empirically confirm the existence of objective moral duties because these are abstract objects). So how then would you prove the existence of objective moral duties, if you cannot do so empirically? The only option seems to be to offer a proof, or argument, for the existence of objective moral duties (and this indeed is how the aforementioned ethical philosophies attempt to do so). This leads inexorably to the dichotomy facing moral argument B, either you will:
(1) Make use of god in the proof of the existence of objective moral duties.
(2) Not make use of god in the proof of the existence of objective moral duties.
(1) will make B2 question begging for then you show that the only reason you would have to accept the existence of objective moral duties is if you already accept the existence of god. (2) would obviously disprove B1 because (2) shows that god is not needed for the existence of objective moral duties. For instance, William Lane Craig claims that "Duty arises in response to an imperative from a competent authority...in the case of moral obligations, these arise as a result of imperatives issued by a competent authority. And in virtue of being the Good, God is uniquely qualified to issues such commands as expressions of His nature." Ignoring the issue of the truth of his argument here, it is clear that if this is how you attempt to prove B2, you will be patently question begging, for the atheist would deny that this "competent authority" and his commands even exist, and so in order to prove that these objective moral duties exist, you would have to prove that god exists. But this is what the argument is supposed to be proving, and therefore you must assume what you seek to prove in order to argue for B2.
How do theists attempt to avoid this dichotomy? Sadly, by denying that they actually have to have a proof of the existence of objective moral duties in order to show that they exist. The theist can't empirically show that objective moral duties exist, and he cannot formulate a proof of their existence on pain of either question-begging or disproving B1, how then is he going to attempt to prove his premise B2? Predictably, it is by use of the appeal to intuition. It is said that in we directly intuit that some things we really ought or ought not do, objectively. It is objectively true that we ought not rape little children for fun, the theist claims that we intuit.
While these intuitions have strong emotional appeal, considered rationally, there simply is no weight behind arguments from intuition. I will simply repeat earlier criticisms of intuition here, that the intuition may be true for the proponent of B2, but that does not necessitate it being true for anyone else. We are free to respond that we do not share that intuition, or even that we intuit the falsity of B2. Taken alone, intuition does not count as an objective argument for B2. We should simply respond that the intuition has not been proven to be veridical. Unless the theist is adopting some strange epistemology of intuitionism, intuition will not do anything to prove B2. Human intuition has proven fallible countless times over the course of human history, such that intuition itself cannot count as a real argument for something. To say that quantum physics in unintuitive would not show that quantum physics is not true.
Finally, note that this argument would only be persuasive to someone with low justification for their atheism in the first place. For someone with good grounds for affirming atheism, they would simply say that they have better grounds for affirming the modus ponens form of the argument than the modus tollens form of the argument, such that they would replace B2 with:
*B2. God does not exist.
Yielding the conclusion:
*B3. Therefore objective moral duties do not exist.
The atheist would have to be presented with arguments sufficient to establish better grounds for affirming B2 than affirming *B2. But it seems to me that any atheist worth his salt would have better grounds for affirming *B2, especially considering the lack of good arguments even possible for establishing B2.
Therefore I think that both moral arguments A and B fail to successful establish their conclusions. Argument A faces a dichotomy that results in it either begging the question in A2 or proving that A1 is false. Argument B seems to be false due to B2 being false, not only that but I think that it is actually impossible to argue for the truth of B2 without either begging the question or disproving B1. The only way out appears to be an appeal to intuition, which clearly fails to establish the truth of B2. Finally, moral argument B would only be persuasive to an atheist with already poor grounds for affirming atheism. In my judgement then, moral arguments are the weakest of all major theistic arguments today.
- Does Theistic Ethics Derive an "Ought" from an "Is", William Lane Craig, http://www.reasonablefaith.org/site/News2?page=NewsArticle&id=8215
- The Is-Ought Problem: An Investigation in Philosophical Logic, Gerhard Schurz