Do they though? Here's three things to consider. If Justice is a concept that only exists in the human mind, then how do we explain social animals who exhibit behaviors such as altruism or shunning? From the time we're young, we know that when someone wrongs us it causes us emotional and psychological pain. When things are righted, some if not all of that pain is alleviated. If Justice is an abstract, where do these feelings of pain and relief come from and why do they exist? If Justice were a completely human construct, invented by us, perpetuated by us, controlled by us, and nowhere else. By creating social structures and systems that creates behavior and beliefs centered around the idea of Justice, by treating it as something real and consequential, doesn't that mean Justice exists even if its us who willed it into existence?Abstract concepts like Justice exist within human minds and nowhere else.