Imagine posting the following on a physics forum:

"When a physicist says 'work', they usually mean something along the lines of 'force times distance'. When an average person says 'work', they are usually referring to the subjective feeling of expending effort. I think that a lot of the disagreement regarding the nature of work (i.e. between specialists and layfolk) is rooted in a failure to properly distinguish between mathematical calculations and everyday intuition. Most physicists probably understand the distinction fairly clearly, but you guys only ever talk about force times distance. Why don't you talk about the psychological meaning of work?"

When an average person says "ethics", ey is usually referring to a system of intuitions and social pressures designed to influence the behavior of members of a group.

What you're talking about is generally called morality, or sometimes "normative ethics" (a rather misleading term--see below). Ethics properly defined generally refers to a process of de-escalating moral conflicts and educating ourselves to see others' points of view. As Rushworth Kidder would put it, ethics balances "right versus right". Now, in order for each individual to assert a "right" in the first place, there must be a dependence on some sort of morality, but ethics itself takes our moral intuitions as given: resolution of the conflict is the only thing we can influence.

One application of this is in politics: Jane Jacobs, George Lakoff and Jonathan Haidt all separately claim that the moral intuitions of "left wing" and "right wing" folks are so different as to appear nearly irreconcilable. This conflict thus evolves into a full system of politics, which Bernard Crick called "ethics done in public". The distinction between "ethics" and "politics" probably depends on the scope of the conflict: Whithin small groups of up to 70 people, one can generally apply ethics very directly, using only informal sanction and punishment. This includes such things as etiquette, which as the word suggests is a kind of minimal "negative ethics" dealing with everyday situations, aimed towards avoiding needless conflict and misunderstanding.[1]

As groups get larger this becomes harder to do and one needs to agree to such things as a moral code, and formal procedures such as electoral and legal systems which decrease the potential for conflict, at the expense of requiring more and more trust in central arbitration mechanisms--these may eventually become indistinguishable from simple moral authority.

Now, there is some merit to the idea that at least some moral principles are universal, and thus one can talk about "normative ethics" independent of any ethical or political conflict of "right versus right". For instance, most communities will support such values as fairness, knowledge, honesty and a good, thriving life. However, each of these concepts may itself depend on moral judgments. And even then, this does not mean that any individual's moral judgment can be directly relied upon in a shared or predictable way.

[1] Thus, etiquette and related norms should never be used as an excuse to trump deeper ethics: e.g. it is clearly wrong to dismiss a genuine moral grievance as someone just being "rude" or "disrespecting the community". Unfortunately, authority figures will often do this, not so much in "real world" communities as in online services such as forums, wikis and blogs. This often results in a failure of basic deliberation and rationality, as deep groupthink takes over.

I think that such a topic for discussion would be best introduced by proposing a reason why discussing it would be useful for us. Discussing optimal strategies for pursuing utility functions is useful to us for obvious reasons -- why do you suggest we should talk about "the social meaning of ethics?"

Can you clarify the difference you see, if any, between what you understand "ethics" to refer to when used by an average person, and what you understand "peer pressure" to refer to?

Because if you don't see a difference, I'd just as soon call that "peer pressure." Calling it "ethics" seems to confuse the issue.

In either case, if you have something interesting to say about it, go right ahead.

When an average person says "ethics", ey is usually referring to a system of intuitions and social pressures designed to influence the behavior of members of a group. ... Why don't we talk about the social meaning of ethics?

I get the impression that to a utilitarian, ethics doesn't have a "social meaning" in the sense that it deals with the way society pressures us to behave in a certain way. A utilitarian cares about other people, but ey doesn't pay too much attention to what society wants - given a choice between doing what society wants and doing the right thing, a utilitarian moral realist will try to do the right thing.

... a failure to properly distinguish between decision theory and what society pressures people to do. Most lesswrong users probably understand the distinction fairly clearly ...

They do indeed, but many of them probably deny that "what society pressures people to do" is the same thing as "what is right". And the utilitarians are able to embed their morality in their utility function, and so they use the same decision theory for what is 'right' and for what is 'advantageous'.