I suppose that would require us understanding what the basic function of morality is... my guess is, it's a mechanism for keeping social-order [duh moment]... but if you think evolutionarily; well social-order is a more effective strategy for survival compared to being combative with others [unless it's a survival situation which is why even good people can do 'bad' under desperation].

So if we assume that the idea of morality is to create social-order, the idea that eating other people would be 'right' just wouldn't add up.

Otherwise, if there is no reason to be moral, then there is no point having a morality in the first place?

If anyone interpretation of morality makes it moral then it's self-defeating?

I of course don't assume to know the answer to this on going philosophical dilemma but these are some of my pontifications on the subject

It SEEMS to me that certain moral perspectives are more effective and beneficial to social-order than others.

I see where you're coming from though,

I imagine the small percentage of people whom are purely evil are the psychopaths [and potentially sociopaths] but more so psychopaths who generally feel pleasure at the suffering of others....

But most of the evil in the world we deal with is 'good people' excusing their 'goodness' as a justification for doing 'bad' things.

Always a pleasure to contemplate these things and be challenged on it.