In my opinion, that's the real danger of tying to analyze human beings (highly emotional and irrational beings) using systems of logic and reason as a basis of study. People and any analysis of them that's to be trusted must include allowances for seeming paradoxes. in other words, you have to accept that perhaps the "natural human instinct" is to irrationally put the group ahead of the self in some cases. You also have to allow for the notion that sometimes we just don't make a whole hell of a lot of sense. Which, by the way, is why people need good answers based in morals and ethics the instant they decide that morals and ethics are important to them.
I like to use gun laws as an example. Consider:
- The Fifth Amendment makes it illegal to require someone to provide testimony against himself - the right to remain silent and refuse self-incrimination is guaranteed.
- The purchase of guns requires the filling out of a form that asks the purchaser if he is a felon.
- It is a felony to lie on a federal form of this type.
That means:
The crook is allowed to lie on the form, because to admit he is a felon is to incriminate himself in both the crime of buying the firearm and the crime of falsifying the document. Another way, he's allowed to own an illegal gun, because owning one legally would require two instances of self-incrimination.
Obviously, that's a crap argument and the guy is going to jail for having the gun in the first place, regardless of how he came to own it. However, it shows how the legal mechanisms are in direct opposition to one another.
Another common logical failure is what's called the liar's paradox. It's the one that says:
"This sentence is false"
Or, if you prefer to avoid self-reference (you formal logic bastard, you)
"The following sentence is false."
"The preceding sentence is true."
Can't work. You have to allow for those intangibles like the limitations of language (which is why logic spun right the hell out of the realm of argumentation - it's Aristotle-based root) and into "symbol logic" which frankly has almost no bearing on how people interact or perceive anything.
In terms of morals, they are self-fulfilling necessities. As soon as someone decides that they require a moral structure, they do. You can't reason them out of it. Much like God, it is a faith that they've chosen and accepted, often at the deepest level possible. Worse still, it's even more subjective than religion. Religions at least have common dogmas. Moral codes are almost entirely individual. All you can do in cases of moral dilemmas is to offer options and trust that the person asking will take or leave whatever they see fit.