I don't get it. I thought moral relativism, anti-essentialism, and critiquing social constructs are all elements of post-modernism?

Or are you saying I would rant against postmodernism? Cause while I find deconstruction to be useful in certain contexts, denying the existence of evil as a concept seems like an absurdity.

Instead, I find the challenge to be in defining precisely what constitutes evil in a way that's both narrow enough to not be overextended, while being comprehensive enough to avoid letting certain things slip through the cracks.

For instance, some things are objectively evil. Slavery, rape, genocide, torture, bombing civilians, child abuse, etc. It would be ridiculous to make a moral relativistic argument against that.

Some things are not so clearly defined, however. Is capital punishment inherently evil, or does it ever have justified cause? Is eating meat inherently evil? Does that mean everyone who eats meat is an evil person? Another one is this: does circumcision count as child abuse, therefore making it evil? Is modern capitalism literal wage-slavery, making the entire system evil?

Some people might have firm convictions about the answer to these questions, but if many people have diametrically opposite yet equally firm convictions, does that make the issue in concern a morally relativistic one?

So defining evil certainly isn't a simple task. But if we had to throw out every concept that's hard to define, we'd have to abandon use of the term "fascism" as well (you know what they say about nailing jelly to the wall).

Another question about defining evil: is it a property of actions, of agents (actors; i.e., people who do evil things), or of dispositions (tendencies, habits, attitudes, etc.; things that are consistently held properties rather than isolated incidents), or some other thing?

In other words, if a person tortures a civilian, would you say "He's an evil person," "He did an evil thing," or "He has evil dispositions." Or perhaps some combination of the above?

Outright rejecting the existence of evil, however, is a flaw of post-modernism. And a true post-modernist wouldn't take that to mean that all of post-modernism is flawed, but simply that it has flaws.