I have seen moral subjectivists imply the following argument at times:
Either morality is based on God or morality is subjective.
Morality is not based on God.
Therefore, morality is subjective.
The argument is rarely put this clearly, but I suspect it’s a pattern of reasoning many moral subjectivists follow. They start out as Christians, accept that God doesn’t exist, and conclude that there is no morality, since the only concept of morality they are familiar with is supernatural. (This premise could also be seen as suggested by much of the moral debate in certain areas of the internet, which is mostly between divine command theorists and moral subjectivists.)
This is a bad argument because the first premise is unjustified – there is no reason why objective morality would have to be based on God. This is a Christian premise that there is no reason to accept on a secular worldview.
On a secular worldview, objective morality is much more likely to be based on the desire to live a good life. Everyone reading this likely wants to be happy, and you will be happier if you develop certain character traits in yourself over time. One example of such a character trait is productivity. People who are characteristically productive are likely to be happier than people who are lazy, because they will have accomplished more, so they will have higher self esteem, and they will likely be materially better off (more so than they would have been, at any rate).
This is the approach to morality moral subjectivists need to be considering when they make their case for moral subjectivism, not the much less plausible supernaturalist approach. We don’t use the pattern of reasoning “not supernatural, therefore subjective” in scientific issues, so we shouldn’t use it in philosophical issues.
The Euthyphro dilemma is an argument against divine command theory, the view that God’s commands are the source of morality. On this view, anything that God commands us to do is the right thing to do, by definition, and anything God commands us not to do is the wrong thing to do, by definition.
So, here’s the Euthyphro dilemma, based on one of Plato’s earlier dialogues:
If morality is based on God’s commands, then either God commands us to do things because they are good, or it is good to do things because God commands us to do them.
If God commands us to do things because they are good, then morality is independent of God, since things are good prior to God’s commands.
If it is good to do things because God commands us to do them, then morality is unacceptably arbitrary. For example, God could command us to boil babies alive, and that would make it good to boil babies alive.
Therefore, morality is not based on God’s commands.
This is usually taken to be a very strong argument against divine command theory.
Interestingly, this sort of argument is not usually taken to be a strong objection to other moral theories that base morality on the will of a specific person or group. For example, moral subjectivists don’t think it is a very strong objection to their view that it is consistent with boiling babies alive if my subjective desires incline me to. Moral relativists don’t think it is a very strong objection to their position that it is consistent with boiling babies alive if the group decides to boil babies alive. And so on.
An atheist on CARM posted the following as the OP of a thread:
Many Christians have argued that there are objective moral values. Yet it seems as if all humans get their morals from reality and that morals vary from culture to culture and sometimes from person to person within a culture. If there are objective moral values, how would we know it? And what purpose would it serve if we all have morals based on reality?
I posted this in response:
Hi, I’m an atheist and I am near the end of a BA in philosophy.
I think it is mistaken, on both rational and polemical grounds, for atheists to argue against the existence of objective morality.
All living things face the alternative of life or death, and every living thing has a means of survival to keep them alive in the face of this alternative. Plants have their automatic chemical functions, and the lower animals have instincts. Human beings, however, use reason as their means of survival, which means that they have to exert effort and think about the way they live, not depend on their automatic functions. It is necessary for a human being to define a set of moral principles to live by, and the only rational standard for a moral code is life.
Most people sense that morality has a life preserving function. As a result, they react strongly to the idea that morality is merely subjective, and see this idea as destructive, although they may lack the conceptual tools to articulate this properly. If people have to choose between religion and moral subjectivism, then they will choose religion, as the fundamentalists on this forum illustrate daily.
The only hope for atheists is to articulate a set of secular values that are based on life and disseminate these values into the culture. Such a set of values has been defined by Ayn Rand, and she has provided the means for disseminating them by presenting them in the form of art, i.e., her novels.
You can find elaboration on the argument I made in the above post here.