From guest blogger, Jace.
1. We can only rely on our perception, moral intuitions, and reason to acquire moral knowledge. (assumption)
2. If we only rely on our perception, moral intuitions, and reason, there will be a plurality of moral beliefs.
3. If there is a plurality of moral beliefs, then extreme moral skepticism follows.
4. If one is an extreme moral skeptic, then they are also in moral despair.
5. If one is in moral despair, then they are in a contradictory state of being.
6. Therefore, there must be something more than our moral intuitions which allows us to acquire moral knowledge. God serves such a function.
Premise 2 is clearly exemplified anytime two people have mutually exclusive beliefs about the right course of action. Her arguments from premise 2 to premise 3 fail, however. She claims that there exist disagreements which are not rationally decidable since there is no non-question-begging procedure for determining which side is wrong. According to Zagzebski, when disagreements occur they occur on one of the following four levels of moral belief: the broadest level of beliefs being metaethical, followed by fundamental moral values, then general moral principles, and then particular moral judgments. If a disagreement occurs at the level of particular moral judgments, it may be the case that both parties are rationally justified in their opposing views given that their broader level moral beliefs are different. If two individuals disagree on a particular moral judgment but have the same beliefs in all of the broader levels, then we may infer that there is a lack of information, communication, or reason on one or both sides of the argument.
The issue that Zagzebski points out is that there are many different sets of beliefs which are internally consistent. How can one know which internally consistent moral framework the true moral knowledge lies in? I would argue that it is entirely possible that true moral knowledge lies in both. She rejects this theory on the grounds that this sort of answer is "unhelpful in the extreme". To me this seems to be untrue and even if it were true, it would be irrelevant.
In Zagzebski's example, she has a woman contemplating whether or not to get an abortion and someone tells her that her position is rationally justified and that the contrary position is also rationally justified. This is not the full picture, however. To be rationally justified, one must have an internally consistent moral framework. So a more complete response would be to say that her position can be rationally justified and that the contrary position can also be rationally justified. The position which actually is justified depends on her moral intuitions about the relative values of life, bodily autonomy, quality of life, and many other factors. Given these moral intuitions she may use reason to construct an internally consistent moral framework. It is this framework that would be incredibly helpful in determining which choice is the right choice for her. Even if a complete moral framework were unhelpful in determining some particular moral judgment, that would not be a good reason to reject the theory that two opposing positions can both contain true moral knowledge.
She may object that the argument changes what is meant by "true moral knowledge" and so doesn't properly handle the issues that she raises. I actually agree, however, I think that this understanding of true moral knowledge is more rational and helpful and, if adopted, does resolve the issues that she's raised. I realize that this may not be satisfying, but I believe that it does a better job at solving the problem than her solution. On her view, a belief in god allows us to be rationally justified in our moral beliefs. However, this only pushes the issue back further on whether we can have a rational and non-question-begging procedure for determining which god to believe in. Given her criteria for becoming an extreme moral skeptic, it is inconsistent for her not to become an extreme theistic skeptic. Relying on intuitions about god leads to a plurality of theistic beliefs for which there is no objective criteria for determining which theistic belief to hold given that there are multiple internally consistent theistic beliefs.