In society as we know it, cannibalism typically occurs during survival situations. And it is in this extreme situation of survival do we see that it is justifiable to eat our own -- so long as there was no other choice (read: Donner Party). So, despite its wide disapproval on moral grounds, many good and moral people will become cannibals under extreme circumstances. In a post apocalyptic world the practice of feeding on ones own kind will become popular because food will be scarce/gone.
I think cannibalism may work just fine for some but as for me, I'd rather eat something else that doesn't walk upright and put up a good fight. Food should lack intelligence so it is easier for me to kill or collect. However, babies don't walk upright, put up a fight or have much intelligence. But that doesn't mean I'm going to make a BLT (babies, lettuce and tomato) out of one. No, I think eating people is wrong. I'm not sure why exactly but maybe its because no one ate me when I was a baby. Since I wasn't eaten, I was able to grow up and live a full life. A life where I can think about whether or not it is okay to eat people. So, no people for me thank you. Check back when the apocalypse happens to see if my mind has changed.