Adam Tyson wrote:Your diagram of the argument is good, and the prephrase should be to link the conclusion to the premise by connecting the "rogue" elements with a conditional arrow that points clockwise, up from CS to MC: CS 
MC
To negate that, say that MC is not necessary for CS, that CS can exist even if MC does not. That's what I mean by making the necessary condition unnecessary.
You're almost there!
Please allow me to follow the thought train of this threads.
So, I believe that in order to negate correctly, we really need to figure out the specified subjects.
1. Apparently, there might be thousands of the moral codes; however, neither we are talking about the moral codes, always requiring people to ignore their own welfare, nor we are talking about the moral codes, never require people to ignore their own welfare. We are specifically discussing one particular moral code, the one that " sometimes " require people to ignore their own welfare.
Based on the premise, If such people exist, people who follow the moral code that sometimes require them to ignore their own welfare to help others, then it must be true that such people do have empathy.
Conclusion: Civilized society can exist only if empathy exist.
So, one of the most crucial point here is that, the necessary condition of the conclusion should be properly translated as to particular group of people who follow the moral code that sometimes require them to ignore their own welfare, but not the empathy in the general.
as a result, the assumption made here is that if civilized society can exist, it must be true that those particular people discussed from the premise " exist " in that particular civilized society.
Answer B - fail to empathize others does not mean there are no any other moral codes to " stop them from acting to damage " civilized society.
Answer C - we do not know that any one whom be willing ignore their welfare will necessary follow the moral code, and we also do not know if whom acting as such would be sufficient enough to civilize the society.
Answer D - * Be careful, the moral code discussed here is not as the same as the moral code from the premise. The moral code discussed here requires people disregard their own welfare to help others. In the other words, this new moral code here requires people " always " disregard their own welfare. In that sense, it is definitely unnecessary to have this new moral code to arise within some civilized societies, since as long as we have people who follow the moral code, requires them " sometimes " to disregard their own welfare at those society, it may still be civilized.
Answer E - we do not need any tendency to have people to " at least " do certain things sometimes.
You sometimes give up playing NBA 2k20 during your leisure time and take your girl friend out for dates just to make your girl friend happy does not necessary mean you have tendency for doing so.
Correct Answer A
Civilized society can exist only if there are people who are willing to " at least sometimes " ignore their own welfare to help others.
To best negate the answer, we are not negating the answer by making the opposite of the original necessary condition necessary; instead, we are negating the answer to making the necessary condition unnecessary.
If we are making the opposite of the original necessary condition necessary, answer A will be looked like -
" Civilized society can exist only if there are people who never being willing to ignore their won welfare to help others "
However, it does not really break the argument, since there can still are people who " at least sometimes " being willing to ignore their own welfare to help others.
If we are simply negating the answer by making it unnecessary, answer A will be looked like
" Civilized society can exist only if there " are not " people who at least sometimes being willing too ignore their own welfare to help others. "
Apparently, this destroy the argument.
Please let me know if my thoughts are correct, and I do appreciate any critics.
