Moral relativism sets out to explain moral diversity: people disagree about what's right and wrong, and these disagreements can be difficult to resolve. Moral relativists account for this by saying there are no moral absolutes: no eternal, universal moral laws that apply across culture, gender, time, etc. Morality is basically a matter of convention. If there are no absolutes, then moral disagreements are illusory, like my daughters arguing over whether watching Fairytopia in German is fun or boring. Mina enjoys it, Javi doesn't, and that's all there is to say. There is no fact of matter, nothing objective you can point to to settle the case. There is no end in sight for this argument unless I can convince them their claims are relative to their own tastes (or Javi learns German).
Isabel isn't a moral relativist – very few philosophers are – but does feel the pull of the current of popular thinking in that direction. One reason for its popularity at street level is that at first glance, it looks like a pretty good account of our experience that morality shifts around. Thirty years ago caning naughty children was accepted as normal in Australian schools, today it is would be met with horror; in some countries bribery is the accepted and expected way of doing business, in others it's punishable; in some Aboriginal communities it was wrong to speak to your mother-in-law, in ours it would be wrong not to; it was wrong for God's people to eat pork in Old Testament times, but is permissible now! All this seems undeniable: does this mean what is good and right is changeable? Is morality relative? I don't think it is, so what's going on in these cases?
For many of them there is a general moral rule that can be applied in different ways in particular instances. So the general rule might be “children should be disciplined”, and there might be many different ways this can be done, different ways being accepted in different cultures and eras. That is, the general rule is a moral absolute, but the particular application is relative. This would also explain why there are lots of different ways of showing respect and being polite in different cultures. Lots of cases that look morally relative can be explained in this way.
Cases can also look morally relative where we have a false belief about moral rightness in a given context. So bribery may just be wrong regardless of whether it is normal business practice or not. Obvious examples of this also include culturally acceptable abuses of women (at least what we would see as abuses!), and child labour. Claiming these are not morally wrong for members of that culture is a hard bullet for the moral relativist to bite, but you can't consistently believe in moral relativism and human rights, which are absolute and universal.
Still other cases can be analysed according to what the rule is meant to achieve. It is wrong to drive on the right hand side of the road in Australia, and on the left in the US. In both cases, an arbitrary decision is made to achieve a purpose (in this case, road safety) by an authority who has the right to our obedience.
I don't think moral relativism is right, but could someone consistently be both a Christian and a moral relativist of the kind I've discussed? The answer has to be no. Christians believe it is good and right for all people in human history, across all cultures, to honour, love and obey the creator, and to treat one another as we would be treated, and that it is wrong not to. These are moral absolutes, and though they can be applied in many different ways in many different situations, they are good and can never be made evil.
· Stanford Encyclopedia of Philosophy (online)
· Cambridge Dictionary of Philosophy (Ed. R. Audi)
· Oxford Companion to Philosophy (Ed. T. Honderich)