One of Plato’s most famous dialogues is between Socrates and a guy named Euthyphro, a supposed religious expert. Socrates questions Euthyphro on the definition of piety, and Euthyphro is forced to say that what is pious is what is pleasing to the gods while what is impious is what is displeasing to them. Socrates further critiques him by pointing out that the gods have enmity and conflicts with one another in the stories and that they seem to simply be going after their own preferences. If so, then clearly the gods are not aligned on what is pious or just, making their mere preferences merely arbitrary. Euthyphro gets caught up in this contradiction and has no answer.
This argument has long been adapted to critique the idea within Judeo-Christian theism that God is needed for objective morals to exist. The argument goes like this: Is something good because God commands it, or does he command it because it is good? If it is the former, then “the good” seems arbitrary; it is all about God’s preferences, and he could conceivably due crazy things like designate rape to be good. William of Ockham is famous for what is called “divine command theory,” the most simplistic of which allows for this possibility. If God wanted to say that theft or torturing babies is good, then he could do so and we have to obey. However, few Christians would be comfortable in saying that God could willy-nilly change the definition of what is good, as it does not seem to give any reliability to morality.
The other horn of the dilemma is to say that God commands something because it is good. However, if so, then it seems like morality is something apart from God. In that case, God is not needed to explain the existence of objective morality and the atheist can happily claim objective morals without believing in God. The theist, then, is caught in a contradiction in his own beliefs: God is either just arbitrary (so he is not good), or there is a moral law apart from him (again, he himself is not the source of good).
The typical Christian response is that, quite unlike the Greek gods, God is the lone Creator and Sustainer of everything. Also, he is eternal and so is his character, and goodness is simply a part of who he is. Thus, when God created the world and gave commands, they simply flowed from his character. This is not arbitrary because God, as an eternal and necessary being, has always been this way and will always be this way. Nor does this mean that “the good” is outside of God, obviously. The atheist, of course, can deny that God exists, but if he goes there he simply concedes the point: There is no contradiction within theism itself regarding the belief that God is needed for objective morality, so the dilemma fades away.
The irony here is that I would argue that Euthyphro’s dilemma takes on considerable force when applied to modern atheists who want to uphold objective morality. First of all, even if we were to grant the argument above, all the atheist has shown is that if objective morals exist, they can possibly exist without God. The atheist has not shown that objective morals do in fact exist, much less exist in a purely material way. More importantly, the main reason Euthyphro could not answer Socrates was because of the multiplicity of gods who have a multiplicity of preferences and goals that often conflict. He had no recourse as far as appealing to an unchanging, eternal Creator; it is precisely Euthyphro’s polytheism that leaves him confused. With that in mind, one can see how this applies to many atheists: If objective morality is based on society or other human constructs, then that is simply some form of “polytheism” that collapses under the weight of different preferences.
Atheists who try to avoid moral relativism typically appeal to some sort of human definition or decision to ground morality. Many simply say, “Society decides.” However, Socrates’ question then comes up: Which society? There are a lot of them, they have different preferences, and they often fight. This would be arbitrary because not only is a particular society’s values then decided by who is strongest within that society, morality as a whole would be decided by what society is the most powerful. That’s hardly a desirable way to ground morality given that history is filled with rather colorful dictators or totalitarian regimes.
Others try to give better ways to ground morality, such as the social contract theory. However, the social contract theory fails due to the same considerations; it’s just a collection of agreed upon values (in theory), and in addition to there being no guarantee that more powerful members of society will ignore or seek to change that “contract,” there is no guarantee that every society will come up with the same one. It’s still based on humanity, and there is no avoiding that there are a lot of humans who have different preferences and goals and who fight each other for them.
So Socrates would ask the modern atheist: What is good? If it is simply what humans decide, then that is arbitrary. If it is something apart from humans, then what is it based on? Here, it is difficult to see what atheists can point to without making appeals to something immaterial, a distasteful prospect for most atheists these days. After all, not only does that remove materialism as a viable worldview, it opens the door for that immaterial “good” to be simply called “God.” Small wonder why many atheists now just bite the bullet and reject objective morality, but that comes with its own host of problems that other atheists find even more undesirable.
Perhaps many forms of atheism shouldn’t be called “atheism” per se; it seems like they are more like polytheism, with the “-theism” part coming from their deification of human beings. And what lousy gods human beings are.