This is the fundamental problem of cultural relativism, one of the guiding ethical principles of the post-liberal left and right. Whether it be worded as “right and wrong are social constructs” or “all have fallen short of the glory of god,” cynicism is not only inevitable, but lacking any redemptive strategy, behavioral expression becomes accepted as only ever being self-serving in the most venal of ways. The history of this is in the seemingly innocuous social commentary that “all politicians are corrupt.” If there’s no variation in judgment, there’s no incentive to not be as bad as desired.