By "a moral world", I mean that many actions or states are categorized as good or evil, and that this is a good measure to evaluate whether we should do these actions of reach these states, regardless of other measures such as expected utility or pleasure.
For example, I can understand why societies that discourage murder will probably fare better than societies that promote it. I don't understand why murder is bad, if not because God said so.
So it seems like "moral world" doesn't mean world that is fundamentally moral, but rather, world in which things are good and bad, am I right?
Seems like most answers here don't try to answer this :P
I think it is conceptually similar to property rights. In the beginning, there is no fundamental fact of who own what. At first, it's a game of dibs. Animals squat on territory and defend it. It's a tooth-and-claw negotiation. Eventually, we end up with a highly systematized notion of property rights, which mostly avoids conflict. Who owns what is mostly a straightforward fact.
Indeed, "don't steal" is part of moral reality, so this is an example, not just an analogy.
We can easily extend this story to other parts of "natural law", for example, murder. A person's life is sort of their own property, and so, murder is similar to theft.
Thing like lying are a bit less analogous, but I claim that we can think of these things as the result of a complex distributed negotiation in the same way.
Skeptic: if ownership and morality are the result of a complex distributed negotiation, how can they be fundamental facts? Isn't my story contrary to that idea?
Me: A fact is just something that is true. Are you saying it's not true that (EG) I own my computer? This isn't such a strange state of affairs. An extreme materialist might say that only particles exist. But I think tables and chairs exist. Particles might be more "fundamental", but tables and chairs are real. A materialist might call tables and chairs social constructs, but this does not make them less real.
Skeptic: But you admit that property rights are the result of a complex negotiation. This suggests that the negotiation could have gone differently. Wouldn't that make morality different? How can we rely on morality, if it's arbitrary?
Me: We rely on facts that could have been different all the time. For example, I'm currently sitting in a chair which could have easily been placed in a different location. If that were the case, I could not be sitting here. So what is the objection, exactly?
Skeptic: But moral facts don't seem like that. They seem more like mathematical facts: 1+1 is necessarily 2.
Me: Well, just because our current beliefs about moral concepts are the result of a complex negotiation, doesn't mean morality is defined as the result of such a negotiation. We could be wrong about moral facts. We've changed our minds on such topics in the past, so, we could change our minds in the future.
Skeptic: Which is it, then? Are moral facts necessarily one way, or are they contingent?
Me: I don't have to make my mind up on that. I'm just trying to defend the idea that there are, indeed, moral facts.
Skeptic: I already believe that. I'm looking for an explanation of how there could be such a thing, if not because God said so.
Me: Well, I'm not 100% sure on that, but I think it's similar to looking for an explanation of tables and chairs. Which would be: it's nice to have flat surfaces to put things on. Similarly for morality: it's nice to have.
Skeptic: Using Aristotle's terminology, that's a final cause. I'm looking for a material cause, like how light is explained by photons. What do moral facts consist of?
Me: How very physical-reductionist.
Skeptic: Hardly. I think the material cause is God's word.
Me: If I say that killing is wrong, I think that fact consists of all the anguish felt by people when loved ones die, together with the fear of death, plus other negative consequences which would plague society if murder wasn't seen as wrong.
Skeptic: That seems very inspecific.
Me: If I had described what murder consists of, it would have been simpler. The material cause of tables and chairs is simply wood and nails (or, whatever it happens to be made of). That's simple because tables are an object. The material cause of a fact like "it's conventient to set things on tables" would be much more complex, consisting of facts about how center of balance works, the height of human hands, etc. Maybe I don't think facts have nice material causes like objects do.
Skeptic: I think the fact that something is good consists of God's word. I also think the good consists of God's word.
Me: I guess I think the good is just, like, all the good things in the world taken together.
Skeptic: Then how do you decide what's on that list?
Me: I still think the fact that something is good consists of all the positive consequences.
Skeptic: Doesn't that just go into an infinite regress?
Me: Not really? I think there's some stuff that's just good, and the rest is derived from that. Like how in physics, there's got to be some stuff at the beginning which just happened (IE, the big bang). But that's efficient cause. For material cause, I guess the analogue is that particles or strings or something just are, they aren't made by any further things.
Skeptic: But isn't it dissatisfying to have something that just is good, with no explanation?
Me: You won't let me have an infinite regress, and you also won't let me cut off an infinite regress? I could similarly ask you want "God's Word" is made of, and put you in a similar dilemma. You have to stop somewhere. Or go on forever. One of the two.
Skeptic: The difference is that I've explained "good" purely in terms of something else, where you've stopped short of that.
Me: I think that's a weird standard to apply here. Particles aren't explained in terms of something else. And your story will similarly have to stop somewhere, like with "God" or something.
Skeptic: Particles can be explained with equations.
Me: Particles don't consist of equations. You asked for "material cause" type explanation, not description. I think I could describe the good purely in terms of other things. Not easily, and not completely, but I think the holes would be due to my imperfect knowledge of the good, which seems like an acceptable excuse.
Skeptic: It sounds like such a description would be long and detailed. Sort of like asking for a description of particles, and getting a big list of things that happen in experiments, the current locations of specific particles, and so on. I want a simple explanation -- the sort of thing scientists demand.
Me: Well, scientific explanations aren't necessarily material causes. Material composition can be complex, agreed? My scientific explanation is the property rights thing.
Skeptic: That was supposed to be a scientific explanation?
Me: I have in mind evolutionary game theory.
Skeptic: Wait, you're saying morality is genetic, or something?
Me: Not biological evolution -- not necessarily. Although, certainly many species including humans have genes relating to territorial behavior. But, no, I'm saying that the math of game theory relates to the evolution of property rights and other facets of morality. I don't have the full equations, like physicists have for the standard model, but I think game theory would be the place to look. I'd recommend The Evolution of the Social Contract by Skyrms, which shows how some basic ideas like fairness can emerge. I am fairly confident that these ideas explain how these concepts got into human brains in actual historical terms, at least.
Skeptic: I don't know why you think that's plausible, but let's suppose that to be true. I'm still baffled why that would make them true, or make them real. Presumably, you think similar things explain how religions got into human brains, but you don't think those things are true and real.
Me: Humans suppose that something is "real" if it's a supposition which helps them explain the world. I think religions have been surpassed by better explanations. I don't think the same is true of morality. Hence, I still think morality is real.
Skeptic: I agree that humans have a tendency to suppose things when they help make sense of the world -- but that doesn't make those things real. It sounds like you think morality is a useful mass hallucination.
Me: I wouldn't disagree with that statement, but I further think it's real.
Skeptic: Because you're going along with what you see as a useful mass hallucination.
Me: Not just that. As a general principle, it doesn't make sense to discard an idea that helps you make sense of the world, until you've found a better idea which makes more sense.
Skeptic: But this isn't like tables and chairs. It's not made of anything. It doesn't exist anywhere.
Me: It's a bit more like 1+1=2. It makes sense to postulate numbers, because they help me make sense of the world.
Skeptic: But numbers don't physically exist. They're mental constructs.
Me: I thought you weren't a materialist?
Skeptic: I thought you were.
Me: I think numbers exist in the same way other things exist. To be honest, I believe in tables and chairs, and that's already a pretty big departure from extreme physical reductionism. Numbers are a mental construct the same way tables and chairs are. That is: they're not. The mental construct describes numbers. The numbers themselves exist independently of the minds.
Skeptic: That's quite a statement.
Me: It's about what "exists" is supposed to mean. Do you want to hand over "exists" purely to physicists, and place other things, like tables and chairs, into a grey zone of "sort of exists for everyday purposes, but actually, when we're talking seriously, only physical particles and such exist"?
Skeptic: Obviously not.
Me: So don't be so reductionist. Tables and chairs exist without a simple scientific description. So morality can, too. I think there may be a good theory of morality, but I don't have to believe that in order to believe in moral facts. Why do you have to reduce morality to God's word? Don't get me wrong, reductionism is great. You should reduce things to parts if you can. But that doesn't mean things don't exist if you can't.
This isn't quite relevant, but I'm curious what you think of Beyond the Reach of God, and it seems a little related.