tomasfritzhansen:

I like your comments chomolungma. They are insighful.

I have one disagreement though, and that is your characterization of of serial killer arguments as strawman arguments. If we are being consistent here we must recognise that there really isn't anything objectively wrong with serial killing. Indeed we all do it with other species all the time. Take fishermen for example. They serially kill fish for fun. Most people consider fishing good wholesome family sport (though for the record I personally find it barbarous).

And some people kill humans for fun. It's not strawman to compare these things. We cannot say "oh, well, obviously this doesn't apply to serial killing, which obviously is wrong".

Thanks. Technically, I think you are right about serial killing, the arguments against the existence of objective moral truths apply to it in a similar way as to less extreme examples. However I think it is a strawman in the sense of not being the strongest (most persuasive) possible argument to engage with. Even if there is technically no objective way to say that serial killing is wrong (who knows, perhaps psychopathy is just an alternative evolutionary strategy?) many people will see this as moot, it's so universally abhorred that it may as well be objectively wrong and arguments to the contrary are more of a philosophical curiosity than a serious issue. However if it turns out that disagreements about hot-button issues like euthanasia and abortion that have reasonable and moral people on both sides simply do not have objectively "true" answers, that's pretty significant and a widespread acknowledgment of this could have major consequences.

Jos Gibbons:

I would have thought that was obvious; namely, the matter of whether there are moral truths.

In that case I strongly disagree. The situation is not the same - the existence of moral truths is much more compatible with theism. That's not to say it's all smooth sailing for theists, the still have to contend with Euthyphro's Dilemma and other objections, but positing the existence of a universal mind or even just a Platonic realm makes it plausible that there could be such a thing as objective moral values that transcend cultural variation and differences of individual preferences. (Of course this is a fantasy, but this is theism we are talking about). In a purely material universe, moral statements are necessarily predicated on categories/concepts with socially constructed meanings ("private property", "sexual immorality" etc). For these statements to have an objective truth value there would need to be some essentialist, "true" meaning to them, which isn't possible without reference to some kind of transcendent standard.

Why mustn't the criterion rely on it?

Because if the criterion relies on utilitarianism then we are implicitly assuming the set of moral axioms that define utilitarianism. The argument effectively becomes "assuming utilitarianism as a moral truth, moral truths exist". It's a tautology. If utilitarianism, then why not Sharia law, or the Code of Hammurabi?

When refuting an argument it's worth pointing out every way its conclusions may not hold. Even the lack of moral truths is open to question. That it is a uniquely atheistic scenario is especially open to question.

Sure, it's possible that even if a god exists there may still be no moral truths.

It is not an ACF. In the case where they act on religious pricniples, their errors aren't a result of their disliking moral relativism; their errors are rationalised by divine command theory. In the case where they cherry-pick, that fact demonstrates they imagine a false difference between the implications of theism and atheism.

Isn't the point of divine command theory and monotheism in general to establish an (albeit imaginary) universal moral authority? I also disagree as already stated that there is no difference between the implications of atheism and theism here.

You asked why we do something. You think us doing it leads to our vilification. Perhaps it does, but it doesn't subtract from the reasons I gave for what we do.

You brought up vilification of atheists, not me.

You don't falsify individual axioms; you falsify the conjunction of all of them. To say an implication of one set of moral precepts and a set of (genuinely or hypothetically) empirical facts is incompatible with another set of moral precepts is to say that the set of all of the aforesaid moral precepts is incompatible with the empirical facts in question.

I believe I acknowledged that sets of axioms may be falsified by showing them to be inconsistent. My point was that this isn't enough to adequately discriminate between competing sets of axioms as more than one set maybe logically consistent and compatible with observed data (more below).

The same thing happens in the philosophy of science; it's called the underdetermination of theory by data. It doesn't prove either non-cognitivism or non-realism, nor would a genuine proof of the former prove the latter, since truths could be unknowable.

OK here we're starting to get to the meat of it. In science, underdetermination of theory by data doesn't matter for all practical intents and purposes, insofar as one of the jobs of science is to make accurate predictions of observed reality. If two theories both correctly predict observed data then we can use either. However the point of a theory of ethics isn't to describe or predict empirical observations (although those do impose relevant constraints), it is to prescribe the morally correct course of action. If two ethical theories are both logically consistent and consistent with observed data but prescribe different courses of action then we are stuck! The crux of the issue is that all the constraints on what makes a good descriptive theory (consistent with observed data, is logically self-consistent) are open to objective verification, whereas only a subset of what makes a good prescriptive theory are (the above plus prescribes morally correct action). We're forced to fall back on our subjective moral intuitions for the last one.

In any case, many real-life ethical disagreements are contingent on other facts. People who disagree on which policies should be used often fail to share knowledge of certain statistical facts concerning their effects, including (but not limited to) the efficacy with which they achieve their aims. Insofar as an increased consensus on such facts directs the moral conversation, it tends to increase moral consensus too.

This is true in a limited sense. For example, if I accept as a general principle the statement "it's morally wrong to cause avoidable harm to human children" and I subsequently discover that hemlock is poisonous, then I can derive the statement "it's morally wrong to give hemlock tea to three year olds". Superficially, that is a moral statement that has been arrived empirically, but on closer inspection all the moral content flows from the general statement that precedes the empirical data, it's not from the data itself. If you trace it back to its origins you will end up back where we started, hashing out moral axioms.