In "But I Could Be Wrong" George Sher explores the implication of the fact that our moral beliefs have been significantly affected by our upbringing and life experiences and argues that, despite this, we may still rationally give our particular moral views precedence over any others. The argument that is commonly put forth to show that we have no logical reason to act on our own moral beliefs is as follows:
P1. "I often disagree with others about what I morally ought to do".
P2. "The moral outlook that supports my current judgment about what I ought to do has been shaped by my upbringing and experiences, for (just about) any alternative judgment, there is some different upbringing, and set of experiences that would have caused me to acquire a moral outlook that would in turn have supported this alternative judgment".
C. Thus, I have no reason to give precedence to my moral beliefs over those that oppose mine.
In other words, this argument says that if any person grew up in a different household they would have just as likely acquired different moral beliefs due to different experiences and cultural views, which means that there is no reason to act on the random set of beliefs that you ended up as opposed to the set of beliefs you could have ended up with. Sher reasons that the only way to argue against this argument is to find fault with P2 since P1 is uncontroversial. He first tries to show that P2 is false because our moral beliefs can change as we get older, as can our religious views, and thus we have reason to trust our particular set of moral beliefs due to the amount of reflection we have put into constructing them. However, there still is no basis for thinking that I have any more thought into my beliefs than you have. Sher then goes on to construct his final argument that will show that even if our views may have been different under different circumstances, we still may rationally give precedence to ours:
P1.1. There is no reason to give precedence to my moral beliefs over those that oppose mine due to P1 and P2.
P2.1. If I were to set aside moral components to judgments, I would lack any basis upon which to make reasoned decisions since any other basis would also be rooted in my experiences and upbringing.
C1. Therefore, practical rationality precludes my setting of my moral beliefs aside when making judgments.
I agree with Sher's argument that we may rationally give precedence to our own set of moral beliefs. I think Sher's argument is important because it should hold up no matter whether one is a moral realist or not, or whether one ascribes as a utilitarian, virtue ethicist, etc. It is interesting to note that a study1 I read recently showed that there may be some genetic influence on our political beliefs, meaning that the environment we grew up in does not entirely impact the political views that we end up with. This could possibly apply to moral beliefs as well and would show that any other upbringing may not change (all of) one's views. However, I don't think that this takes away any from the initial argument since there is still no reason to believe that the possible genes that influence your moral beliefs are any better than anyone else's, but it would mean that P2 would need to be slightly altered in order to not only rely on environmental factors.
Sher, George. "But I Could be Wrong." Ethical Theory: An Anthology. Ed. Russ Shafer-Landau. Blackwell Publishing Ltd, 2007. 94-102. Print.