? quoting Tracer Bullet
It is a sticky problem, but I take issue with this statement. I am a moral relativist, but a strange one. You might call it "mechanistic relativism". The only purpose of ethics is to govern the interaction of agents (people) within a large ensemble (society) with the objective of competing successfully with other ensembles. By this definition, all that defines right and wrong is what works. If all agents are taken to be identical, then all that differentiates one ensemble form another is it's rule set. Over time the "rules" are continually tested, and the good (competitively advantageous) ones are kept, while the bad (competitively deleterious) are discarded. Thus, the basis of ethics is absolute, if empirical in nature. There are many possible solutions to the problem of survival, but each of them is based on the absolute doctrine of success, and the validity or normative nature of that solution is based on it's viability.
To bring this back to concrete reality, western culture has been wildly successful, which to me provides plenty of reason to respect traditions of the past. It is important to test them, think on them, and try to figure out which are still viable and important. That is part of the process, but I think it is a mistake to change them too rapidly.
That's an interesting theory, and one I've come across before in various guises.
I have both general (methodological) objections to these theories, and specific objections to what you said.
The methodological objection
Evolutionary arguments are often attractive in philosophy, but they are rarely correct. Indeed, such arguments are perhaps the most seductive modern form of an invalid argument.
The problem with evolutionary arguments is that you almost always end up assuming what you want to prove. The general structure of an evolutionary argument goes thus:
- Premise 1: property X, of which P is a possible instantiating mechanism, is a survival-pressured characteristic.
- Premise 2: survival-pressured characteristics are always optimised due to evolution.
- Premise 3: P is survival-advantageous over other possible mechanisms.
- Conclusion: By evolution, P is the actual mechanism that instantiates the survival-pressured characteristic X.
There are several problems with this. First, premise 2 is incorrect. Evolutionary pressure finds, at best, local maxima, not global maxima. Moreover, evolution is a continuing process. It follows that survival-pressured characteristics are not always optimised. A process of evolution may indeed reach a dead-end, unless sufficient survival pressures are added to the system to inculcate a temporary evolutionary regress (you need to take one step backward before you can take two forwards).
Second, premise 3 is sneaking an old-fashioned essentialist argument into a "modern" evolutionary argument, which is totally wrong-headed. The whole point of any evolutionary argument is that the process of evolution will judge which possibilities are the most functional; premise 3 is assuming that the philosopher can make this judgement!
If the philosopher is going to make an essentialist judgement (X is essentially better than Y because of my reasons....), then he should not hide it in an evolutionary argument. How does he KNOW that P is survival-advantageous? He's assuming that P "fits the job" better than the alternatives, but that requires that he know the "essential requirements" of the job. But this requires that he sneaks a sort of functional essentialism into his evolutionary argument.
So you can see that premise 3 is the point where the argument effectively assumes what it intends to prove.
For these reasons, the only good evolutionary arguments are those that back up their assertions with reference to the fossil record. Without this, anyone can make a vague essentialist claim and dress it up in Darwin's coat.
The specific objections
Now, your argument does not appear to be of exactly this form, which is a good sign. I think, however, that there are other fundamental problems with your assessment of ethics:
You see the purpose of ethics as promoting successful behaviour in a group. I agree that this is probably how ethical behaviour arose: cooperating groups were more successful than selfish individuals, so they tended to survive to pass on the cooperative characteristics.
These characteristics may be passed on by genes or by learned behaviour. I think the latter, but note that this question is independent of our other considerations here.
The main problem with your theory is that it only deals with the objective side of ethics, and does not address the subjective concerns. By failing to address the subjective concerns, I believe it fails in the major task of an ethical theory: to reconcile an objective understanding with our subjective ethical perspectives.
What does it mean to be successful? If you are talking about survival, what kind of survival do you mean? Purely numbers? Supporting the largest possible population? Does it matter at all whether the individuals are miserable throughout their lives?
Incidentally, what makes you think Western culture is successful? On an analysis based on population size and growth, China and India seem to be the star performers.
I think that your notion of success in Western culture includes, at least tacitly, ideas about quality of life. But quality of life has no causally necessary links to survival chances, and in practice a high quality of life tends to reduce the chances of producing many children and passing on your genes.
Unless there is a necessary correspondance between quality of life and prospects of passing of passing on your genes, then your theory occupies a dubious position. The burden of proof is on you either to demonstrate such a necessary connection, or to demonstrate that it would not be possible to produce a biologically successful society that has appalling quality of life.
I do think there's something to be said for your theory -- it gives a refreshingly practical perspective, and I believe it contains important truthful elements. But, in its present form, I think it makes a category error by asserting that this facet of ethical theory -- the evolutionary element -- is in fact the WHOLE of ethical theory.
Clearly biological competition was the generative influence of what we now call ethical behaviour; but the human race has developed beyond the crude need for survival. We are now a species that look for meaning, not just meals. Ethics is about our society and how we relate to one another, and issues that do not affect survival can still be ethically relevant.
There are many ways in which we could continue to develop as a biologically successful species. But some of them involve greater cruelty towards each other, or widepread misery in our daily lives. Others involve the opposite.
It may well be that the most biologically successful possible future is one in which humanity develops into a cruel militaristic species, which seeks to dominate other forms of life while at the same time actually lowering the quality of life for individual humans.
Some people would say this has already happened. I am more sanguine.
Now that humanity is no longer under the evolutionary pressure it once was, we require measures of success that are not purely based on survival numbers. Ethics is not merely the rules of maximal survival of groups; it concerns the quality of life of individuals within those groups, and how that quality of life is affected by the actions of others.
Place the other person's text inside the start/end quote markers, then write your reply afterwards 
***chews toungue furiously
