Why be good?

[Randy Carson]

Jenny-

If morality is purely a social construct, would you have a problem with a society that requires that widows be burned on their dead husband's funeral pyres like the Hindus required? Would you object to Muslim society in which little girls are subjected to genital mutilation?

These practices were/are agreed to by the majority if not unanimity of these cultures. Who are we to impose our values on them?

You forget that I live in and have been educated in a particular society and largely share that societies morality.  So yes I have strong objections to both genital mutilation and burning widows on funeral pyres.  But the people who live in those countries might not, yet they consider themselves to be moral.  Obviously the standard is subjective.

However, a subjective standard does not mean one can't argue that one set of morals is better than another.  It's just the the appeal can't be made to a higher authority such as god.  By the way, you do realize that both of these objectionable practices are at their roots religious practices.

Jenny-

Let's broaden this a bit just for a moment.

Suppose an alien race arrives on our planet with a completely different set of values. 

They immediately rape all earth women in order to impregnate them while killing off all earth males. )BTW - Rape is considered a good thing on their planet because females should be honored to be the recipient of the males attention and seed. You won't mind that now that you can see their point of view, will you?)

Oh, and the reason they've come to earth is to begin farming us for food. So, your offspring, cute little mutants (you'll be bearing a litter, actually), will be consumed by the male who mated with you.

Now, remember, in their culture, rape is not wrong. Nor is the subjugation and consumption of humans.

So, why should this alien race be "good" when it is in their best interest to do otherwise?

Have they evolved differently? Or not at all? Or is evolution really not such an adequate process by which to develop "good" and "bad" behavior?