Is there a word for the tendency of morals to become inverted over time or by society? I feel like there should be some concise psychological jargon for it... Probably a Greek word...

"Sin" encapsulates it, but its not precise enough. Sin can mean either an action or a state. "Corruption" is closer, but can also mean a state and has political connotations. "Evil" covers it, but with its religious connotation, isn't useful if speaking to an academic, and is too loosely defined anyways.

I'm looking for a word that names the momentum of the drift to the bad - the force that pushes from the straight and verifiable, which befuddles the mind and creates illusions. Justifications... Compromise... But the impulse behind that.

Dangit, my vocabulary is too small !!!