Why be good?

[Randy Carson]

Can atheists justify, according to atheist principles, why they believe it is "wrong" to pollute oceans, cut down rain forests, or hack into someone’s bank account and steal their life savings? If the stronger members of the human species engage in such behaviors in their pursuit of dominating the weaker members, and if there is no God and therefore no transcendent, prescriptive moral law given by God to guide us into knowing what is right and what is wrong, then on what grounds can atheists legitimately oppose such behaviors?

You really like strawmen don't you.  There is no such thing as atheist principles.  Atheism is not a philosophy.  It is a state of being in which a person does not believe in a god or gods.

Individual atheists myself included might have various reasons for why they believe theft and murder are wrong.  Some may also be environmentalists, but not all. 

I personally believe somethings are wrong and somethings are right out of a combination of gut instinct (evolution is at work there I'm sure), empathy for others (evolution again), social training, and reason.   If I were to state my operating rule when in doubt it would be this:  choose that course of action which you would have required if you were able to write the rules for humanity before your sex, race, nationality, abilities, etc. were known.

The justification is simple.  Morals are there to allow people to live together in the most mutually advantageous way possible.

Doing so would be intolerant and would have the net result of the atheist forcing his morality on others -- the very thing atheists object to in the first place.

First of all, once again not all atheists object to religious morality.  That generally isn't why atheists are atheists.  (hint it's that little matter of the complete lack of evidence for god).

So what is the justification for imposing my morality on others?  None, I don't and I can't.  But society can enforce it's morality and does so in the form of laws and social interactions.  In democracies those laws enacted based upon societies common sense of morality.  When one religious group attempts to take control of this process the results tend to be bad for society as a whole.  Secular morality is therefore preferable.

And, as it happens, I do object to strictures imposed by religious persons when the only justification for it is my god says so. Let me give you an example.  Thou shalt not kill is pretty much universally accepted as a good rule, advantageous to society as a whole. Thou shalt not eat pork is not.  Nor is thou shalt not take the name of the lord in vain or thou shalt have no other gods before me. My objections come in the form of political participation and/or appeal to the First Amendment.

Jenny-

If you Google the terms "theory of evolution' and "natural selection", you can read about the "survival of the fittest".

The reason we know about certain cultures such as the Spartans, the Visigoths, the Mongols, etc. is because they dominated those around them and survived. And within those "small groups", the alpha male led the group and passed on his genes through the offspring of the females he wanted. 

Now, in this thread, you can see how eager many are to backpedal away from this fact of nature because of its implications. But the lacuna is the transition from "survival of the fittest" to feeling warmth and empathy toward the weak and less fortunate members of the group. After millions of years of dominating and even killing off of the weak, are we to believe that we have recently begun looking out for others - even at our own expense? I'm not saying that does not happen in isolated cases, but it does not serve the long-term interests of the group to do so.

So, given that evolution is a presupposition in most atheists' belief system, then I am interested in hearing an explanation for the obvious incoherence resulting from holding simultaneously that:

1. any species that evolves does so on the basis of natural selection and survival of the fittest, and
   
2. man has evolved in a different manner such that being "good" is now more beneficial to the group/species than the dominance of the weak by the strong.
   

Thanks.