This is not true and not the point of the argument. The nihilist can easily distinguish between the suffering of infants and the suffering of criminals, for example, and claim that if objective morality were true, the former would be unjustifiable in a way that the latter isn't. The truth of the conditional does not follow from the nihilist's beliefs but from the theist's, which the nihilist aims to show are inconsistent.

The theist can, of course, deny this conditional and claim that the suffering of infants is justifiable, but his reasons for doing this would not be convincing to the nihilist. Either way, the argument is not over whether objective morality is true or not, but what the implications of it would be.

To put it bluntly, while I believe in neither a benevolent God nor an objective evil, if I believed in either of these things, I could not reconcile it with the other, and I am not convinced that you can do so, either.

I don't really understand your revised claim as it seems to contradict what you say below about how the problem of evil assumes nihilism. Are you claiming that the atheist needs to have some view about morality in order to present the problem of evil? Because if so, then I disagree.

No. While these arguments are consistent with nihilism, they don't imply nihilism either. If you are a moral realist, then you can accept the premises of these arguments without being inconsistent.

I don't see why not. Moral realism doesn't imply that there are no acts of gratuitous suffering or evil.

Note: (2) is not making the claim that it is logically necessary that if morality is objective then gratuitous evil must exist. Rather, it is making the claim that if morality is objective, then in the actual world gratuitous evil exists. Thus, it is assuming some contingent facts about the world, such as the existence of pointless suffering and so on.

Then it would seem the nihilist would be required to accept p as true:

(p) If morality is objective in our world, then (X) God exists.

The problem I see is if the premise isn’t asserted in good faith, then the whole argument is somewhat vacuous. OrP’s argument is in modus ponens and so just asserting the premise on the grounds that it is trivially true, without a conditional proof (A, therefore B), leaves the nihilist no way to enter the argument other than supporting an evidential premise like ‘God does not exist’ to deny the consequent of (p). In other words, asserting his ideological claim ‘there is no objective morality’ is nothing more than denying the antecedent, so what is the non-trivial purpose?

I’m guilty of over generalizing the terms, but in the context of these arguments it’s somewhat tacitly admitted that to cause gratuitous suffering is to signify a suffering so bad that only God could redeem it, like the murder and torture of small children or genocide.

I’d argue that if the omni-3 God actually exists, then necessarily there are actually no gratuitous evils, only our inability to understand things.

Just going to point out that the argument I presented is not modus ponens (at least the one you've been discussing is not).

The problem as I see it for the moral relativist is that Hitler can mount his own argument from evil. And with his definition of evil being very much different than another’s, it comes down to evil according to whom.

I don’t know. Moral realism doesn’t entail that God cannot redeem objective evils (making them non-gratuitous) in the way nihilism defines them away. So it seems to me the moral realist would need a supporting argument for why ‘some objective evils are gratuitous’, without begging the question by asserting God doesn’t exist.
I'm reading that as (2) is a contingently true (?) which doesn't seem quite right. I'd think (2) needs to be true regardless of there being a world with volitional agents or not.

?

Modus Ponens:

1) If A, then B.
2) A
3) Therefore, B.

My argument, which interprets the problem of evil as a reductio ad absurdum argument, uses a "chain argument" to generate the contradiction. The notable feature of chain arguments is that, unlike with modus ponens or tollens, they only require that you assert hypothetical statements. This is why there is no point in my argument where I assert the antecedent to any of these hypotheticals:

4) If A, then B.
5) If B, then C.
6) Therefore, if A, then C.
7) If A, then ~C.
8) Therefore, if A, then C and ~C.

I don't understand what you mean by Hitler's problem of evil. I am not saying that the nihilist just defines evil however she wants. Presumably she is working with the definition of evil put forward by the theist.

Huh? You are the one claiming that moral realism is inconsistent with the claim that gratuitous evils exist. As far as I know, the only defence you've offered for this claim is the argument that moral realism implies that God exists and God's existence implies that there are no gratuitous evils exist. I've claimed here (and defended at length elsewhere) that moral realism doesn't imply that God exists, so of course I'm not going to agree with you that moral realism implies that there are no gratuitous evil, especially because it seems so extremely obvious that there are such evils.

The problem with saying that (2) is only contingently true is that some people think that if morality is objective, it has to be objective in all possible worlds. In that case we would be making the kind of second-order modal claim that I am not comfortable with. So I'll just stick with my statement as I framed it. I think the meaning of it is clear enough, as you seem to be the only one that doesn't understand it and, no offense, your interpretation of logical statements can be very non-standard. So, as I said before, the claim would be that given certain facts about the world we live in, under normal accounts of the objectivity of morality, if morality is objective, then gratuitous evil would exist.

As for whether (2) has to be regardless of the existence of volitional agents, I see no motivation for such a claim.

well it seems intuitive that certain things about the physical world 'just are' on some fundemental level, although mass supposedly is the result of subatomic particles interacting with the higgs field - not sure why you would consider that spookier than any other physical property emerging from physical interactions. and in any case no example of an observable or measurable physical property, reduceable or not, is going to illustrate that your claim of a metaphysical property is consistent with the way the universe seems to work.

i was asking why anyone should care. there's certainly an advantage to being able to detect and measure physical properties. but even if a metaphysical 'should/shouldn't' standard existed, and somehow was able to attach to our actions and we could somehow detect it, of what use would it be? in what sense would it be preferrable to follow it rather than follow our own utilitarian moral opinions? in what sense of 'true' would it be the true standard and our opinions false? being concerned with a mind-independent moral standard seems no different than an atheist being concerned with sin.

why only the physical world? Why isn't it equally intuitive that the nonphysical world (possibly empty) would also have fundamental features?
Yeah, I tried to make reference to the underlying interactions. I find it useful to provide Newtonian illustrations, even though they're wrong, since most people are more familiar with that level of physics (including me). I can lift my game to QM or relativity though, if you'd prefer.

it's spooky because there's no answer - stuff just happens like that. There's no reason that things keep moving unless acted on by a force. Inertia is a spooky, unexplained brute fact about the world.
perhaps not, but remember that my goal isn't to persuade you that it's true, merely that it might be a sensible concept.
I don't think it would be necessarily useful, nor knowable. I don't think transfinite arithmetic is useful either. Some people like knowing true things, so they may enjoy striving to emulate this objective morality.

Why should I be concerned by utility? I'm describing how I think the world is - whether it's useful to us if the world actually is that way is a pretty poor standard of truth, in my view.

i don't know what 'nonphysical world' means, so am unable to intuit much about it

i can't even make sense of the semantics.

i don't see how it wouldn't be obviously completely unknowable, since it would be effectively indistinguishable from a random subjective standard.

if it's not useful in any sense, how is it not completely arbitrary in relation to us? if it's completely arbitrary in what sense is it morality? why call it that? murder is wrong might as well be murder is purple.

I think this is the strongest criticism of moral objectivism - at least you're at the point of saying there's something obvious about a concept you previously declared meaningless. I'm going to take that as progress.
it's as arbitrary as the gravitational constant. Arbitrary seems wrong though - we don't get to choose whatever we want. That's the point.
I don't think it's arbitrary.
murder is purple doesn't mean anything.

Certainly! (Edit - Although if came to believe that morality is objective, he might change his view on that conditional.)

Consider...

1. If P_N is the largest prime number, then we may list the primes 2,3,...P_k...P_N.
2. If 2,3,...P_k...P_N are all the primes, then M := 2*3*...*P_k*...*P_N+1 is not prime.
3. If M is not prime, there is a prime P_j which divides M.
4. If P_j divides M, P_j divides both (M - 1) and M.
5. If P_j divides both (M-1) and M, then P_j divides 1, which is absurd.

---------------------------------------------------------------

Therefore, there are infinitely many primes.

(Cf. The Elements of Euclid, With Dissertations, Clarendon Press, Oxford, 1782, page 63. Trans. James Williamson.) Edit - the point is to expose the logical structure of the concepts involved.

the fact that i think it's an inconsistent (incomplete to be accurate) concept doesn't keep me from picturing a detached standard floating in the air somewhere. kind of like picturing the will of god if god didn't or couldn't enforce his will in any way.

i think that's just part of what makes it meaningless. you're proposing 'something' that mimics a possible set of our subjective moral opinions, and can't be said to do a better job at morality than our opinions by any meaningful definition of better. in what way is this an idealization of behavior?

i was trying to say it might as well be arbitrary since it would be of no practical importance to us no matter what it is. we might not exist if the gravitational constant were different. a mind-detached moral standard could be anything and it would still be irrelevant as it would not qualify as a guide to behavior in any practical sense.

how do you know? maybe there's a metaphysical idealization of purple that attaches to murder

(murder is ugly would have worked better)

the correct subjectivist response here, imo, is to ask what the "is wrong" predicate is supposed to mean. as someone who doesn't believe in objective morality, I really do have a hard time interpreting "murder is wrong" as anything other than something like "I don't like murder, and I don't want people to murder other people...etc". Strangely enough, I do think that some normative claims have an objective basis (I insist that there are truths when it comes to the scientific method and decision theory, for instance!). but ethics? no truth to be had there.

the notion that "murder is purple" or any random string of symbols can turn out to have meaning is just odd to me.

been there done that. the bunny response is 'corresponds to <shouldn't do> within some objectively existing mind independent, matter independent idealized standard of behavior', which i think is nonsensical.

that was more or less my point. without any possible utilitarian aspect, wrong in 'murder is wrong' might as well be any other random word as far as we are concerned. it's irrelevant either way.

We are all agreed about this and the argument from evil hinges on it. The question is why you should hold on to an omni-3 God when gratuitous evil seems obvious. Sure, you could say that there is some way to justify apparently gratuitous evils and we are too stupid to discover it, but I think you can see that this is a terribly weak defense. For one thing, it undermines moral realism by making moral truths inaccessible to human reasoning.

If A, then B.
If B, then C.
If C, then D.
A.
Therefore, D.

Isn’t that a valid form of Modus Ponens, or must it be reduced to one conditional (if A, then D) to be taken as valid?

Since anyone who assents to (3) in your original argument...
... will assent to (3) below, one can continue the chain in the most direct and obvious manner to show the absurdity of asserting “God exists,” correct?

1. If God exists, then morality is objective in our world.
2. If morality is objective in our world, then gratuitous evil exists in our world.
3. If gratuitous evil exists in our world, then God does not exist.
4. Therefore, if God exists, then God does not exist.

If so, can’t the theist just cite your argument to show the absurdity of the nihilist position? That is, a nihilist is one whose belief set entails the claim: if God exists, then God does not exist.

The conditional...

If God exists, then God does not exist.

...is logically equivalent to...

Either God does not exist or God does not exist.

...and of course a nihilist believes this!

P.S. Have you considered that you might be the first person in history to reject Euclid on the grounds that he didn't argue in good faith?

The argument in full Modus Tollens form would read:
6. There is not the absurd.
7. Therefore, P_N is not the largest prime number.
8. Therefore, there are infinitely many primes.

In order to say that (8) is true one must affirm (6) is true, as with (4) and (3) below.

1. If God exists, then morality is objective in our world.
2. If morality is objective in our world, then gratuitous evil exists in our world.
3. Gratuitous evil does not exist in our world.
4. Therefore, God does not exist.

Thus, any atheist who actually employs Original Position’s argument against theodicy must affirm (3) is true to conclude (4) is true. From which, any atheist who does not really believe or denies (4), must also reject the argument as anything other than an argument nihilists support.

Now granted, Original Position’s intent was not to produce a slam-dunk argument from evil that all atheists would support, but rather to prove wrong my claim that only by an appeal to objective morality can the atheist mount the argument from evil, which admittedly he achieved. However, only at the expense of the denial of morality to the degree of one who believes (4) is false.

Can you explain how/why this is true?
How/why is an "if then" statement equivalent to an "either or" statement?

"If A, then B" is always equivalent to "Either ~A or B." The statements are interchangeable.

Sure, if you only consider the portion of the argument that is strictly a chain argument, then the conclusion is:

If there are infinitely many primes, then 1 has a prime divisor (which is absurd).

The point is to provide a logical analysis which shows, if one wishes to believe in a finitude of primes, one must be prepared to believe absurdities.

As for the rest of your post, you did not actually reproduce Original Position's argument. His argument was:

1) If God exists, then morality is objective in our world.
2) If morality is objective in our world, then gratuitous evil exists in our world.
3) If God exists, gratuitous evil doesn't exist in our world.
4) Therefore, if God exists, gratuitous evil both doesn't and does exist in our world (which is absurd).

You see the intended effect is exactly the same as in Euclid's argument: to provide a logical analysis which shows, if one wishes to believe God exists, one must be prepared to believe absurdities.

I would think I'm more proposing that we each have some moral code which can be characterised as a set of statements we hold to be true and that these are a subset of a, probably infinite, larger set of potential moral codes. I dont think the objective moral standard is of a fundamental different character than each of our subjective codes - it's one of them, it just happens to contain only true statements (whereas each of ours probably includes at least one false statement).

'Can be said to do a better job...' isnt something that interests me. In my view, as it happenes, the moral objectivist is in the ethically identical position as the moral subjectivist - even if I'm right about this privileged moral code, I'm stuck with my own subjective view as to what right and wrong is. My belief in moral objectivism is not based on any perceived utility. (Though it at least helps me maintain consistency when I decry 'might makes right' yet still believe it's moral for me to try and enforce my moral views. I dont know that a subjectivist can do the same consistently).

I have further views as to how we know about this morality - but essentially they amount to no more than an appeal to mystery. I dont claim to have an answer to why we are able to recognise the truth of moral statements anymore than I can answer why proof by contradiction is compelling.
If there is no way to know about this objective morality, it couldnt be a guide to behaviour. Although I'm not interested in providing arguments for moral knowledge at this stage (we'd have to start a new thread in which we at least accept the existence of a spooky 'moral code' to do that. Otherwise I'm going to have to qualify what I say so much, I'm just going to get confused), I do actually believe we can come to know the truth of moral statements.
Original Position has me mulling over whether I should deem ugly to be objective too, so yeah I agree this is better.

(FWIW, I think 'purple' means some physical property. I dont think that's what good means. If you want to explain what metaphysical purple is, I'll probably be a receptive audience...)