Doug S. - see here for one objection to Fyfe's view.

Incidentally, the lesson I take from Nagel's paper is that it's not really "common knowledge" that's the problem, so much as the act of raising such common knowledge to public salience. (We may still refrain from publicly acknowledging even facts we're privately quite certain that everyone else is also privately certain of, and so on.)

See also Nagel's 'Concealment and Exposure':

"Admittedly nonacknowledgment can sometimes also serve the purpose of deceiving those, like children or outsiders, who do not know the conventions. But its main purpose is usually not to deceive, but to manage the distinction between foreground and background, between what invites attention and a collective response and what remains individual and may be ignored. The possibility of combining civilized interpersonal relations with a relatively free inner life depends on this division.

No, the real work is done by leaving unacknowledged things that are known, even if only in general terms, on all sides. The more effective are the conventions controlling acknowledgment, the more easily we can handle our knowledge of what others do not express, and their knowledge of what we do not express. One of the remarkable effects of a smoothly fitting public surface is that it protects one from the sense of exposure without having to be in any way dishonest or deceptive, just as clothing does not conceal the fact that one is naked underneath. The mere sense that the gaze of others, and their explicit reactions, are conventionally discouraged from penetrating this surface, in spite of their unstated awareness of much that lies beneath it, allows a sense of freedom to lead one's inner life as if it were invisible, even though it is not. It is enough that it is firmly excluded from direct public view, and that only what one puts out into the public domain is a legitimate object of explicit response from others."

For example:

"At the same party C and D meet. D is a candidate for a job in C's department, and C is transfixed by D's beautiful breasts. They exchange judicious opinions about a recent publication by someone else. Consider the alternative:

C: Groan....

D: Take your eyes off me, you dandruff-covered creep; how such a drooling incompetent can have got tenure, let alone become a department chair, is beyond me.

The trouble with the alternatives is that they lead to a dead end, because they demand engagement on terrain where common ground is unavailable without great effort, and only conflict will result. If C expresses his admiration of D's breasts, C and D have to deal with it as a common problem or feature of the situation, and their social relation must proceed in its light. If on the other hand it is just something that C feels and that D knows, from long experience and subtle signs, that he feels, then it can simply be left out of the basis of their joint activity of conversation, even while it operates separately in the background for each of them as a factor in their private thoughts."

Poke - "most 'moral' differences between countries, for example, are actually economic differences"

I'd state that slightly differently: not that moral differences just are economic differences (they could conceivably come apart, after all), but rather, moral progress is typically caused by economic progress (or, even more likely, they are mutually reinforcing). In other words: you can believe in the possibility of moral progress, i.e. of changes that are morally better rather than worse, without buying into any particular explanatory story about why this came to be.

(Compare: "Most 'height' differences between generations... are actually nutritional differences." The fact that we now eat better doesn't undo the fact that we are now taller than our grandparents' generation. It explains it.)

Jess - "shouldn't we all just grab a textbook on introductory moral philosophy?"

That would seem ideal. I'd recommend James Rachels' The Elements of Moral Philosophy for a very engaging and easy-to-read introductory text. Though I take it Eliezer is here more interested in meta-ethics than first-order moral inquiry. As always, the Stanford Encyclopedia of Philosophy is a good place to start (then follow up Gibbard and Railton, especially, in the bibliography).

On the other hand, one shouldn't let the perfect be the enemy of good discussion. Better to reinvent the wheel than to go without entirely!

"moral progress, in my view, consists of better reasoning to make our morality more and more consistent"

Right, so morality is not our [actual, presently existing] "set of evolved norms" at all, but rather the [hypothetical, idealized] end-point of this process of rational refinement.

Try replacing every instance of 'morality' with 'logic' (or 'epistemic normativity' more broadly). Sure, you could create a mind (of sorts) that evaluated these things differently -- that thought hypocrisy was a virtue, and that contradictions warranted belief -- but that's just to say that you can create an irrational mind.

I'm puzzled by Eliezer's claim that anybody ever thought there were "universally compelling arguments", that would convince every mind whatsoever. Who in the world (not made of straw) does not believe that irrational minds are possible? (We come across them every day.) Surely the not-transparently-ridiculous position in the vicinity he criticizes is instead that there are arguments which would be compelling to any sufficiently rational mind.

"Richard has credentials. I have competency."

Funny. Again, just out of curiosity, what is your basis for thinking yourself philosophically competent? A self-gratifying intuition, perhaps? (Credentialing by acknowledged experts, though an imperfect guide, is at least some protection against quackery.) I haven't even seen you make an argument, let alone a good one; all you do is make unsupported assertions and attempt to ridicule people who know more than you do. You appear to suffer delusions about your own abilities and the extent of your understanding. (As you say, "the inability... to perceive the wrongness with their arguments is generally insurmountable" -- what puzzles me is why this doesn't make you more humble about your own intuited greatness, given that nobody else is nearly so impressed.)

Now, you change the subject by shifting the burden to others, asking them to list the accomplishments of academic philosophy. (It's beyond dispute that our understanding of thousands of philosophical problems has advanced significantly in the past century -- just browse through any entry of the Stanford Encyclopedia of Philosophy, or my own dozen favourite 'Examples of Solved Philosophy' -- though of course philosophical progress does not readily translate into technological progress the way that progress in other disciplines can.)

The question HA is raising (and that I can readily confirm) is that you do not seem to know what you are talking about. From what I can tell, you are completely ignorant of the field of philosophy and the work that goes on in it; so there is no reason for anyone to take seriously the unargued denunciations you offer from on high. You don't even know what it is that you're denouncing. You are to philosophy what young earth creationists are to biology.

Of course, if you offer a reasoned argument then others may consider it on its merits. (Even a stopped clock is right twice a day, and all that.) But you lack the authority to make mere assertions and expect anyone to take your ignorant pontificating seriously. That's all.

I've a new post - 'Non-causal Talk' - which points out some problems with Eliezer's assumption that our words refer to whatever causes us to utter them.