Suppose an evil king decides to do a twisted moral experiment on you. He tells you to kick a small child really hard, right in the face. If you do, he will end the experiment with no further damage. If you refuse, he will kick the child himself, and then execute that child plus a hundred innocent people.
The best solution is to somehow overthrow the king or escape the experiment. Assuming you can’t, what do you do?
There are certain moral philosophers who would tell you to refuse. Sure, the child would get hurt and lots of innocent people would die, but it wouldn’t, technically, be your fault. But if you kicked the child, well, that would be your fault, and then you’d have to feel bad about it.
But this excessive concern about whether something is your fault or not is a form of selfishness. If you sided with those philosophers, it wouldn’t be out of a concern for the child’s welfare - the child’s getting kicked anyway, not to mention executed - it would be out of concern with whether you might feel bad about it later. The desire involved is the desire to avoid guilt, not the desire to help others.
We tend to identify guilt as a sign that we’ve done something morally wrong, and often it is. But guilt is a faulty signal; the course of action which minimizes our guilt is not always the course of action that is morally right. A desire to minimize guilt is no more noble than any other desire to make one’s self feel good at the expense of others, and so a morality that follows the principle of according value to other people must worry about more than just feeling guilty.