Philosophers on Moral Bias

The concept of bias seems to be central to the concept of morality.  Philosophers often say the moral action is simply the action you have the best reasons to do.  But we do not usually treat immorally-acting people as if they had made a random analysis error.  We instead treat them as if they were enemies, acting against us on purpose.  And our explanation is usually that they are biased. 

What are these key moral biases?  A few years ago, when writing a Bioethics paper, I collected these quotes from six philosophers, John Rawls, Peter Singer, Norman Daniels, John Arras, Jan Crosthwaite, and Richard Brandt: 

John Rawls: We can discard those judgments made with hesitation, or in which we have little confidence. Similarly, those given when we are upset or frightened, or when we stand to gain or lose one way or the other can be left aside. All these judgments are likely to be erroneous or to be influenced by an excessive attention to our own interests.    

Peter Singer: All the particular moral judgments we intuitively make are likely to derive from discarded religious systems, from warped views of sex and bodily functions, or from customs necessary for the survival of the group in social and economic circumstances that now lie in the distant past. 

Norman Daniels: [Moral] opinions are often the result of self-interest, self-deception, historical and cultural accident, hidden class bias, and so on. 

John Arras: It may well be that some of our most strongly felt convictions, far from being obviously right, are actually the fruit of profoundly unjust social practices and institutions. If we could just step back and gain some critical distance, the injustice might become visible.   

Jan Crosthwaite: Feminist analysis is concerned less with conscious motivations than with discerning underlying assumptions, and patterns of thinking and practices, of which people may be quite unaware. . . . It also prompts reflection on the possibility of gender biases in the theoretical frameworks of bioethics.

Richard Brandt: One important source of ethical errors is doubtless the complexity of ethical problems. . . . Another important cause to which differences of ethical opinion may be ascribed is the degree of maturity of the person judging. . . . A third source of “error” or disagreement [is] . . .the distortion or warping of the organ of insight by passion, disinclination to make any sacrifice of pleasure or the lower values, and so on. . . . [I]nterest may prevent us from seriously examining a problem although we may talk as if we had done so; or it may make us rest with an incompletely analyzed conception; or it may make us ignore certain factors in the situation of which we are vaguely aware and which we would consider if we were honestly interested in an impartial and objective view.

So, is there a consensus here on the sources of moral error?