I'm going to comment on some statements by apostate atheist Jeff Lowder,
Steve’s first link is about Sharon Street’s paper, “A Darwinian Dilemma about Realist Theories of Value.” Street’s paper has nothing do with an alleged contradiction between moral realism and atheism. In fact, Street’s paper has nothing whatsoever to do with moral ontology. Street’s paper is about moral epistemology: she argues that if evolutionary naturalism is true, we have an undercutting defeater for trusting our second-order ethical intuitions. In plain English, it’s as if she says:
“Many people think moral realism is true because it seems like moral realism is true. But that isn’t a good reason to think that moral realism is true if you are an evolutionary naturalist. If evolutionary naturalism is true, it would ‘seem’ that moral realism were true even if it weren’t. So the ‘argument from seeming’ [my name] isn’t a good reason for evolutionary naturalists to think that moral realism is true.”The other part of Steve’s Rosenberg post includes the same basic point about natural selection tricking us into believing moral realism is true. It fails for the same reason as Shermer’s and Flannagan’s.
For now, I will simply point out that (1) even if Ruse’s argument were correct, it would provide no support for the claim that atheism and moral realism are logically incompatible; and (2) Ruse’s moral anti-realist argument fails because it commits the genetic fallacy. Indeed, it contains the very confusion Steve described in his (ii): Ruse confuses moral psychology with moral ontology. So both Steve and I agree that Ruse’s argument against moral realism fails.
i) To begin with, slapping the "genetic fallacy" label onto a position doesn't make it fallacious. There are people who mechanically apply a list of alleged fallacies to arguments. They don't stop to consider if the alleged fallacies are simplistic.
At the risk of stating the obvious, the source of beliefs or truth-claims can be quite germane to assessing the veracity or probability of the belief or truth-claim. For instance, making decisions based on astrology, fortune cookies, Tarot cards, or dial-a-psychics is irrational and harmful because those are unreliable sources of information regarding future outcomes. That's not a trustworthy way to evaluate the consequences of your actions.
Likewise, when assessing testimonial evidence, the source can be quite germane to our evaluation. Is it a reliable source of information?
ii) One of Jeff's ploys is to pretend that when atheists repudiate moral realism, their repudiation is purely incidental to their atheism. Jeff's evasiveness is symptomatic of someone who's in a state of intellectual denial.
iii) In addition, Jeff's objections suffer from a common incomprehension on his part. This is due to his bad habit of compartmentalizing issues. To say that in critiquing evolutionary ethics, Street, Ruse, Rosenberg, and Flannagan are talking about moral psychology (or moral epistemology) rather than moral ontology misses the point: For them, the problem with evolutionary ethics is that it does not and cannot go any deeper than moral psychology (or moral epistemology). Evolution has programmed us to have certain moral instincts, but there's nothing to back that up. Our conditioned beliefs don't track moral facts. Indeed, evolution has deluded us into believing in nonexistent moral norms. So it doesn't go beyond evolutionary psychology, and that's the problem.
Thomas Nagel. Quoting Daniel Dennett, Nagel endorses the view that if everything reduces to physics, then there is no naturalistic answer to a cosmic question. The cosmic question is put into square brackets. I haven’t read Nagel’s 2010 book, so I can’t tell if the words in the bracket come from Nagel or from Steve. I don’t have enough context for the quotation to make sense of the question put in the square brackets. In any case, I agree that with Nagel that naturalism is nonteleological. I do not find, however, an argument (in Steve’s post) for the conclusion that the non-teleological nature of naturalism is logically incompatible with moral realism.
Nagel details that in the book Jeff hasn't read. For instance, here's his sympathetic exposition of Street's argument:
Street points out that if the responses and faculties that generate our value judgments are in significant part the result of natural selection, there is no reason to expect that they would lead us to be able to detect any mind-independent moral or evaluative truth, if there is such a thing. That is because the ability to detect such truth, unlike the ability to detect mind-independent truth about the physical world, would make no contribution to reproductive fitness…So far as natural selection is concerned, if there were such a thing as mind-independent moral truth, those judgements could be systematically false, T. Nagel, Mind & Cosmos (Oxford, 2012), 107.
Back to Jeff:
First, it could be the case that God does not exist, in which case there is no cosmic teleology, but some version of Platonism is true (and so moral values exist as abstract objects).
i) To begin with, that's a nonstarter for atheists who are physicalists. And it's my impression that most modern-day atheists are physicalists. Appealing to Platonic realism is just a decoy.
ii) What does Jeff think abstract objects are? How do they subsist? It does no good to postulate something inscrutable to salvage your position.
iii) Even if abstract moral universals exist, what makes Jeff think we'd be obligated to them?
Second, it could be the case that God does not exist and a neo-Aristotelian approach to ethics like that found in Larry Arnhart’s book, Darwinian Natural Right, is correct. But Arnhart’s neo-Aristotelian (and Humean and Darwinian) approach to ethics is a realist approach to ethics.
i) I've discussed secularized Aristotelian ethics in response to Keith Parsons:
ii) I just cited secular philosophers who explain the inadequacies of a Darwinian approach to moral realism.
iii) Hume was a classic exponent of ethical subjectivism.