What is justice? It’s a lofty question, up there in the pantheon of “What is the meaning of life?” and “Who let the dogs out?”. There is no great answer for that, but, essentially justice is about doing the right thing. What is right? That’s a good question.
There are three taste buds to justice: merit, need, and equality. When people make an argument for something being right they will draw on one or more of these taste buds. These criteria become especially important when groups decide to allocate goods through non-market institutions.
Here is a favorite example from Peyton Young’s book Equity: In Theory and Practice. At the end of World War II, the United States was demobilizing soldiers in Europe. Some had to be retained to fight Japan while others could come home. Which soldiers should come home first?
After debate, the U.S. Army decided to survey thousands of soldiers in the United States to identify relevant factors. There were four important factors: length of time in the Army, age, amount of overseas service, and number of dependents. Then troops completed a pairwise-comparison of each criteria like in the picture below.
You can see among the transitive rankings (90 percent of those surveyed satisfied transitivity) the two most important features to those surveyed in the United States was overseas service and number of dependents.
But, it turns out there was an important write-in candidate among the soldiers: exposure to combat. A large swath of soldiers mentioned that this should be an important criteria but the Army hadn’t considered it in their survey.
The Army devised another survey that attempted to develop how much different criteria should be weighted. You can see a sample question below and the resulting points system (from a series of questions like the sample question).
What matters most to the troops: exposure to combat and number of dependents. Put another way, what matters most is merit and need. The right thing to do regarding who comes home first involves consideration of whether you merit coming home (exposure to combat elevates you over others) and need (a child needs their parent).
So I do not have a precise definition of justice. But, I have noticed that when people talk about doing the right thing they often rely one one or more of merit, need, and equality.