You seem to think that without a God there is no way to establish any morality. This is an old argument, but not valid.
I have not said this. I have said that a God is the only way to argue the case for an absolute and objective morality. All societies have a moral code of behavior, but they are relative and changing. A god is a useful way to argue why people should subscribe to the moral code, because in this way they can argue that it is absolute and not subject to the opinion of individuals and groups.
In fact, we don't need it as there is a lot of evidence that morality relates to human nature.
This does not mean it is an absolute morality, it just means that in your opinion human nature is the way that morality arises, and for what it is worth, I agree with you.
For example, marriage. Human beings need a great deal of rearing before they are ready to live in the world, and so evolution determines that we must form stable long-term couples. That is a moral issue and it somehow seems 'right'.
Biological pairing does not have to be a moral issue, unless we decide to make it so. In order for a morality to be absolute and objective it needs to exist independent of anything that changes or that exists for a reason other than for morality. While I agree that morality has arisen due to our biology and specifically from our need to survive, but this is not the same as an objective and absolute morality. There is no reason to equate adaptive behaviour to morality, except that it is a useful way of enforcing compliance to social norms
Marriage is a cultural institution that varies across the world, but every single culture has some form of ritual around forming couples.
So what? Even if we say that it is morally ‘right’ to form partnerships, or marriage, for humans it does not make it an absolute. Consider the debate about marriage for homosexuals. Are we now going to say that it used to be ‘right’ for men and women to marry, but not same sex, but now we have decided it is right to same and opposite sex to marry. This is exactly what we are doing, but it means we are simply bending morality to fit what we want. Once again this means the morality itself cannot be absolute or objective, it makes it subjective and relative.
Your thinking seems to be toward natural= morally right, and unnatural= morally wrong. Since morality is subjective then you are free to define morality as you choose, and if you can get enough people to join your moral club then you can stake a claim that your morality has the best support and so should override minority morality groups. This is just human nature seeking to get the best outcome for itself and its group. The key point is that the basis for morality is subjective and relative. In this case the tendency for people to pair. The challenge you have is moral judgement of people who do not successfully, or never pair. Is it therefore ‘wrong’ to not be in a partnership, and how do you deal with people who are serial monogamists? Is it wrong to break a partnership but OK once you get another one.
Jared Diamond is a scientist who has lived with a number of Stone Age tribes in New Guinea and he reports an extreme case of a tribe in which boys are raped ritually by elders. According to Diamond, this tribe exhibits a lot of psychological problems.
So this means you think that as long as there are no psychological problems natural behavior is right in an absolute sense. Something that is absolute and objective means it does not change, even over time and is extant to the agent (ie. humans). It would also mean that every tribe, even in the past would have had to be psychologically dysfunctional, to even consider this behaviour wrong. If we found a single tribe today, in the past or in the future, that did NOT have a psychological issue, and did rape boys, would this mean Diamonds argument collapses, or would we accept and exception to something absolute?
You also need to address just what behaviours we are morally judging. You have mentioned forming pairs and raping young boys. We need to deal with killing others, waging war, theft, lying, raping adults, etc. All these are behaviours that we judge as being morally wrong. If an absolute morality does exist how do we define that we can place all the above in this bucket? By looking to see if they are universally applied and where practiced there are no psychological problems?
Or will we decide that just raping boys and getting married are absolutely moral and theft is relatively moral? How will you define the behaviour. If there existed cannibal tribes in the past who did not have psychological problems, this its not universal.
We also need to address the issue of groups in populations do not do any of the bad stuff, but still have psychological problems. As we have made the link that psychological problems somehow indicates that you can sit outside the moral net (ie. if you do bad stuff you will be found to suffer from a psychological problem – your point). If someone does suffer from psychological problems does this make you morally bad even though you do not exhibit any of the behaviours?
You argument seems to indicate that non pathology and natural behavior underlies moral absolutism. Death itself is natural and non pathological in that it comes to us all, but a pathology always arises in order for us to die. This presents the model with a contradiction. Pathology and natural together. What shall we do with the moral position on this, when the two bases for morality are in opposition? It also does not address the means of death.
Your position overall looks akin to the naturalistic fallacy, whereby what is natural must be good. See wiki on this
My argument would be that this isn't surprising, because this cultural institution of child rape is not in accord with human nature and is intrinsically harmful. While morals are difficult to pin down, I believe this is an example of non-relative morality - we don't need to refer to 'absolutes' to know that child rape is objectively immoral.
What about cannibalism or killing either at a national or personal level war? What about the fact that most shark species practice inter uterine cannibalism? As sharks become viable in their mothers uterus they eat their brothers and sisters? While I accept that we might argue that moral behaviour is only applicable to humans, much of our behaviour is animal in nature thanks to evolution. The fact that we pair or generally support the family unit also exists in other species, and since your argument seems to strongly link the natural behaviour of pairing to morality, how are you able to escape having other aspects of ‘natural’ bring in other traits we have inherited from our animal ancestors?
How do you deal with our eating of other animals? Since you can argue that this is natural behaviour and is necessary to ensure our survival (and that of other carnivores), why can cannibalism not also be natural. After all many animals do eat their own kind.
Ergo, you're wrong to say morals are entirely relative or subjective.
Ergo, you have the wrong end of the stick. The first logical issue you face is confusing just what absolute morality is. Its unchanging and immutable, not affected by time and circumstance. Objective means it comes from sources that cannot be subjective, ie. either it does not come from humans or humans are not subjective (what a dream this is).
Your second issue the equating of natural with right, even though our relative morality does arise from our biology because our culture also does.
If morals were not relative one would expect to find them unchanging, and the same ones held by all people (or even those people who had no pathological problems). Instead we find societies that are cannibals, wage war, deprive people of their liberty, have the death penalty, demonise homosexuals, and then change their minds when their society evolves. Morals are relative because they do change and are subjectively imposed by the society and changed to suit that society.
Is that substantiated enough for you? And all in less than 250 words!
Actually it was a bit light. Perhaps you need to acquaint yourself with some the more considered arguments on moral relativism, I think you might be surprised that quite a bit more has been put into the topic than you reflect in some of your comments. The argument between absolute and relative morality has been raging for millennia by better intellects than yours and mine. This just scratches the surface.