R2D2 wrote:Is there a basis in nature for morality?
Of course there is. Survival of the species. Every species with a brain has rules of behaviour that enhance its ability to perpetuate its kind. Every social species has rules of behaviour that places the long-term interest of the gene-pool above the short-term interest of the individual.
Is there such a thing as a natural right,
No; "right", both as the opposite of wrong and as what an individual is entitled to, are human concepts. They do not exist in nature prior to their expression in human language. However, many species that predate humans have social organizations, status structures, prerogatives and obligations, hierarchies and pecking orders, leaders and followers, allowable and unacceptable behaviours according to one's position in the social structure.
A
right is whatever an individual is able to do that the rest of the group allows him or her to do. The group might be a family, a clan, a tribe, a city-state, a nation or a federation of nations. The laws of the larger organization generally supersedes the laws of the subsumed smaller organization, but sometimes local self-government is accepted.
natural law,
Yes: physics, chemistry, biology, psychology.
or natural justice?
Do well, you live. Do badly, you die. Hard winter, you probably die anyway, even if it's not your fault.
Can human beings know something about right and wrong through the use of unaided reason (i.e., without the help of revealed religion)?
Since they're having to invent it year by year, situation by situation, reason would be a far better aid than religion, which is some long-dead guy who probably couldn't even write dictating (through intermediaries with their own axels to grease) rules from a whole different continent, climate, culture and time period to people he could never have imagined.
Is morality relative to culture, or does it transcend culture?
Social systems are bigger than individual cultures, but they all have some aspects and requirements in common. Lots of people who are not blood-related, and maybe don't even like one another much, have to live in close proximity and interact daily, without excessive bloodshed. The basics are universal; the details are mostly BS.