Matt, in his inimitable style, fairly comprehensively demolishes the argument, but there's a lot of dancing around a point that almost invariably crops up and never really gets addressed in these discussions.
I'll include the video at the bottom of the post for anybody interested, but I want to take a different tack and address the elephant in the room.
Here's the short form of the argument:
P1. If god does not exist, then objective moral values do not exist.
P2. Objective moral values do exist.
C. Therefore, god exists.
As a claim to knowledge, this has about as much substance as Aristotle's claims concerning sexual dimorphism in human dentition. There are several obvious flaws that should be immediately apparent to anybody with more than two functioning neurons, yet somebody with a double doctorate in philosophy can't seem to spot them. Those problems are, non-exhaustively, abuse of the material conditional in P1, the oxymoronic concept of 'objective values' and, of course, our old friend the blind assertion. I'll come back to those to address later in the post, but my immediate concern is the false dichotomy between objective and subjective.
It's often thought that statements fall into two broad categories, objective and subjective, and it's almost always in these terms that this discussion is set. As always, we need to unpack some terms. Since the dichotomous terms are the easiest to address, let's look at those first:
What is meant by 'objective'? Simple: It means 'independent of mind'. It means that something is the case regardless of what anybody thinks about it.
And 'subjective'? Again, simple: It means 'dependent on mind'. It means that something may or may not be the case, and we can each come to different conclusions.
What about morality? What's that?
This is really where the whole thing starts to degenerate, not least because what we think of as constituting morality seems to be liberally interspersed with objective principles, such as that it's 'wrong' to kill or rape but, in the details, to contain much that seems subjective. Of course, trying to define 'right' and 'wrong' leads us further down the rabbit-hole, because we'll often disagree on the details of what is considered to be a right moral action and a wrong one. There are some general principles we can agree on, though, and these are the examples that are wheeled out as 'objective', and that are thought by the apologist to close down the discussion.
Morality is a social contract. It's the mechanism by which we, as a social species, can operate as social animals. It's a broad agreement that we should not unnecessarily inflict harm upon one another. The minutiae of that agreement will vary from place to place but, in general there are things that we can agree on. We can agree that harm is caused when one of us kills another. We can agree that harm is caused when one of us rapes another, or steals from another.
Some of these are not set in stone (well, unless you're of a particular theological persuasion). There are many moral dilemmas littering the ethics literature that show that it isn't always easy to spot what a right action is in a given situation. For example, is it immoral to lie? Yes? Is it wrong to lie to a Gestapo officer about the Jewish family hiding under your floorboards, knowing that revealing them will lead to their deaths?
The long and short of it is that morality requires thought. Having a rigid set of rules is actually counter-productive to moral progress, as can be seen all-too-readily in recent years, with atrocities rendered in the name of this or that deity, or this or that rule, often in a climate in which we're terminally unable to reach any sort of agreement on which interpretation of said rule or deity is the correct one, if any of them are (no prizes for guessing where my money is). With a strict set of doctrinal imperatives that must be adhered to without question, abuse is always on the horizon. Harm will always come to somebody. In such a climate, even mild disagreement on interpretation can get a lot of people hurt, oppressed, marginalised, encamped, decamped or killed, or any combination of those and a litany of other abuses to dignity and our persons.
More specifically, it requires discussion and thought. Rules are the antithesis of thought, and lead to conflict.
I've heard it asserted, on countless occasions, that Western morality owes its existence to Christianity. A vacuous assertion, devoid of any real basis. The simple fact that a set of rules undermines moral progress nullifies that assertion wholesale, and that's even before we get into the content. The first four of the classic ten commandments (there are actually six hundred and thirteen of them) are the utterances of a classic abuser - 'Do what I want and, if you report me to anyone, I'll hurt your family - forever!'.
Rules of thumb are far superior. They give you a baseline for what constitutes harm, while allowing the freedom to properly weight the moral consequences of any given action. I can agree that it's best most of the time to be truthful, but that this isn't to be taken as 'gospel', as little Rachael under your floorboards will attest with some relief.
By learning lessons from these and other situations, we've made progress over the centuries, as our species' moral compass has slowly ground toward magnetic North; abolishing slavery - though not everybody's caught on, founding of principles of equality - again, much progress to be made, I won't bore with a list but, in general, we're making progress, and most of that has come about by recognising that rigid application of fixed rules rarely has a good outcome.
In reality, we're extremely complex individuals when it comes to morality. The way we think about things in a moral context is coloured by all sorts of factors so, like any other area containing a large number of complex variables, it can be quite disordered. Education/inculcation/indoctrination are major but individual experience generates all sorts of biases, many of which we'd struggle to identify. Then we see studies from cognitive science on phenomena like 'priming'. This is an area of study in which people can be 'primed' toward certain decisions based on introduced stimuli. I recommend looking up Daniel Kahneman and his studies, including priming people to be selfish based only on seeing some representation of money, and a lovely one where students are primed to like or dislike somebody based only on the temperature of a cup that was handed to them some minutes prior to the interview. It's a fascinating area, and nails the whole free will debate to the wall for me, but it's only a sidebar to my purpose here.
So we can see that morality, often thought of as monolithic and fixed by many, is fluid and progressive, and must remain so.
So, is it subjective, then?
I've talked before about the core assumptions of science. Here, I want to look at the first two:
1. There exist multiple observers (solipsism is false).
2. These observers can communicate their observations.
Why are these assumptions important? The first is important because, put simply, if solipsism is true, science is an illusion. The second is important because, taken together with the first, these introduce the star of today's show. The resolution to the dichotomy of subjectivity and objectivity: Inter-subjectivity.
Science progresses by ruling things out. It says, 'this hypothesis is in direct contradiction with observation, bin it'. That's it. Any remaining hypotheses that aren't directly contradicted are retained for further study, further generation of consequences until we find a consequence that isn't observed. Generally, the one that most elegantly explains the broadest range of observations, especially unexplained observations, will generally get the most attention, which is why string theory is still with us. These are reached by a broad consensus of specialists in the relevant field, who've checked the work, checked the observations, replicated the experiments themselves in many cases, and broadly, we can say that, under rigorous conditions, all these experts confirm that the proposed experiment does what it's supposed to and produces the predicted outcome. That keeps happening until we find an experiment that fails to generate the predicted outcome, or generates an outcome that the hypothesis implies will not be observed, and we whittle out hypotheses on this basis.
Morality is the same sort of framework. We all know that we feel shame or guilt when we knowingly do harm to somebody. Often, we'll feel shame and guilt when we discover later that an innocent- or benign-seeming act put others in harm's way - even one that, at the time, you couldn't know had moral implications. Evolution has given us a marvellous set of tools to help us in our interactions with the world as a social animal. Lots of lovely chemicals to infuse the brain with emotional states. We know how we'd feel if we were subject to such harm, because we're experienced with our brain chemistry, and have even found ways to trigger it artificially for recreation.
We're not the only ones, either. As much as some will scream that it's not possible, you can readily observe moral reasoning and its effects in animals. No dog owner can come upon the dog when it's had it away with your sausages and tell me that the look on its face is not guilt and shame. If you don't have a dog, watch an episode of Meerkat Manor. There's one who's always being naughty, and you can see the guilt in his behaviour even hours later when his behaviour is discovered. He's just like a human child. As for the artificial triggers, have a look at the Wiki page for Zoopharmacognosy (lit: animal drug knowledge; we don't yet know if any do it for recreation). Hey, Cheech, this cat knows his shit...
In summary, morality is neither subjective nor objective, but inter-subjective. It's no more nor less than the framework that allows us to operate successfully as social animals. It's an agreement, essentially, not to be a dick.
So what about that argument? Let's look at it again:
P1. If god does not exist, then objective moral values do not exist.
P2. Objective moral values do exist.
C. Therefore, god exists.
P1 is a lovely example of abuse of the material conditional. With such a conditional, it's possible to prove just about anything. I could, for example, quite simply prove that the moon is made of green cheese. Here:
P1. If Matt Dillahunty won the argument, the moon is made of green cheese.
P2. Matt won the argument.
C. Therefore, the moon is made of green cheese.
This little bit of absurdity is exactly the same in form as the moral argument. No doubt somebody will accuse me of an argumentum ad absurdum, but this is actually a valid reductio ad absurdum, because the form of the reasoning is exactly the same.
Aside from this abuse, the premise also commits the fallacy of blind assertion. There's no basis for asserting that god is required for objectivity, in morality or anything else, for that matter. Indeed, it's not a stretch to argue that, if morality is subject to the whims of a single individual, then it's subjective by definition.
Many attempts have been made to get out of this, but they all fail. The most common is simply to state that morals flow from god's nature (and indeed the apologist in the video does exactly this). This, rather than supporting the argument, fatally undercuts it, because if morality flows from god's essential nature, then god doesn't have any choice, which means that the source of morality is not god himself, but the nature imposed on him by the universe (god is a subset of the universe and cannot be the creator of it, an argument I'll be dealing with in a future post), which means that objective morality do not rely on the existence of god.
Another major issue with the premise is that it contains a howling oxymoron. 'Values' cannot be objective. It's kind of in the definition of the word. Values are value-laden, at the risk of tautologically saying the same thing twice.
Not only is there no logical justification for accepting the first premise as an axiom, there's actually good reason to reject it outright.
Moreover, on the basis of the foregoing discussion, even were we to accept, for the sake of argument, the veracity of the first premise, we can reject the second outright, because a) it contains the same oxymoron, b) it's factually incorrect, because there are not, nor can there be, objective moral values, nor indeed objective morality.
Also worth noting here that, as pointed out by Matt, the argument in toto commits one of the supernaturalist's favourite fallacies, the petitio principii, because the argument basically says God is morality, therefore god.
As is often the case with such arguments, it's not so much sophisticated as it is sophistry.
Feel free to share and use any portion of this, as always.
Nits and crits welcome but, if you want to debate this beyond technicalities or errors, find me on Twatter. @hackenslash1