Re matters of degree, I would disagree. The opposite of selfishness would be selflessness. This sounds like a good thing, eg being altruistic is assumed to be 'good', but then, it could also be about imposing one's values on someone, and devaluing the self. It could be a means of control (was forced altruism in communist countries 'good', for example). It seems that 'selflessness' - selfishness's opposite - can also be characterised as 'evil'. If it's not clear whether selfishness or selflessness is evil, it's not clear that it's a matter of degrees.
Ayn Rand argues in the "The Virtue of Selfishness" that selfishness is a good thing, if you want to see a lovely alternative argument.
But that was poorly punctuated I meant selfishness or even evil not that they were equivalent.