One of the arguments we've made here over the years is that if there is no God the notion of moral obligation becomes meaningless. Apart from a transcendent ground for moral right and wrong, there can be no duty to act one way rather than another.
Now atheistic philosophers, no doubt weary of having their theistic colleagues point out to them the nihilistic implications of their atheism, have adopted a strategy to answer this criticism of the attempt to develop an atheistic ethics or morality. A paper in Faith and Philosophy (available by subscription only) authored by Erik Wielenberg, makes the bold claim that moral beliefs are what epistemologists call properly basic.
Properly basic beliefs are beliefs which do not require that they be based on any other beliefs. We are within our epistemic rights to hold them even if we can give no reasons or evidential support for them.
Traditionally, many philosophers held that such things as my belief that I'm experiencing pain-like sensations in my tooth (beliefs evident to the senses), that I had cereal for breakfast (memory beliefs), or that I exist (beliefs that are incorrigible or can't be wrong) are all properly basic.
It's self-evident, Wielenberg claims, that cruelty is wrong and kindness is right. There's no need to defend or justify that belief, and no one with properly functioning cognitive faculties would deny it. Thus, there's no need to ground moral beliefs in God or anything else. They're just brute facts and that's all there is to it.
This is a clever move, especially since some Christian philosophers want to assert that belief in God is also properly basic. Wielenberg compares the basicality of belief in God to belief that, say, cruelty is wrong. He then goes on to argue that if belief in God is properly basic then so, too, is a belief that cruelty is wrong.
Now if moral beliefs are indeed, properly basic then it will do no good to ask what the atheist bases his beliefs upon. He'll simply answer that there's no need to justify them or warrant them. Kindness is better than cruelty and that's the end of the matter.
But I'm not so sure. What does it mean to say that something is wrong if there is no God? Presumably it means that you shouldn't do it, but if we ask why we shouldn't, the answer is simply that you just shouldn't.
Suppose I can profit from harming someone and get away with it. Why is that wrong? Wielenberg replies that it just is, that most people agree that it is, and that no further reasons are necessary. This strikes me as inadequate and question begging.
Moreover, setting that aside, the problem is not so much with beliefs about this or that moral act but with the notion of moral obligation. An obligation is something which binds us to act. It must be imposed.
If there is no God then what obligates us to behave one way rather than another? If one person is kind and another is cruel what obligates the first to behave the way he does and obligates the second not to behave as he does?
How can we have a moral duty if there is no transcendent moral authority to impose that duty and to enforce it? In lieu of God where does such a duty come from and why should I feel bound by it?
Finally, what can it mean to say that a behavior is wrong if there's no sanction for performing it?
If there were no law enforcement or judicial system laws would be meaningless. If there's no God then to whom, or what, are we accountable for our acts? Society? Ourselves?
Why should anyone care what society thinks, and if I impose the obligation on myself, surely I can release myself from it if it proves inconvenient.
If Wielenberg is correct, to say that cruelty is wrong is simply to say that a lot of people don't like it, but what people like and don't like can hardly be the ground for what's moral, much less for moral obligation.
The fact remains that moral obligation can only exist in a world in which there is a transcendent moral authority. Atheists can live just the same as theists in terms of their ethics. They can adopt the very same values, but if they chose to adopt the opposite values they would be neither wrong nor right to do so.
In a Godless world, there simply is no wrong or right. There are just things that people, like any other animal, do.