The world is not a fair place, it gives us no guarantees of fairness, but it is part of our social contract to try to be fair with each other. We say that we want what is fair, but that isn't true. We want what is best for us, but we will settle for what is fair. Fairness is a social virtue.
In his book, Moral Politics: How Liberals and Conservatives Think, George Lakoff gives this definition of fairness. "Fairness is about the equitable distribution of objects of value (either positive of negative value) according to some accepted standard."
In short, moral action is fair distribution.
He lists ten models of fairness:
"Equality of distribution (one child one cookie)"
"Equality of opportunity (one person, one raffle ticket)"
"Procedural distribution (playing by the rules determines what you get)"
"Rights based fairness (you get what you have a right to)"
"Need-based fairness (the more you need the more you have a right to)"
"Scalar distribution (the more you work, the more you get)"
"Contractual distribution (you get what you agree to)"
"Equal distribution of responsibility (we share the burden equally)"
"Scalar distribution of responsibility (the greater your abilities, the greater your responsibilities)"
"Equal distribution of power (one person, one vote)"
For the most part I agree with him. But I would describe the models slightly diferently:
"Equality of distribution" (everyone receives an "object" of equal value)
Equal distribution of opportunity (one person, one chance)
Equal distribution of responsibility (one person, one task)
Equal distribution of resources (one person, one cookie)
"Scalar distribution" (the greater the qualification, the greater the compensation) (you get what you deserve)(distribution as compensation)
Scalar distribution by need (the more you need, the more you get)(those with greater need deserve greater compensation)
Scalar distribution by ability (the more you have, the more you get)(those with more skills deserve more compensation)
Scalar distribution by virtue (the more you give, the more you get back)(the good deserve more compensation than the bad)
"Procedural distribution" (the rules determine what you get)
Procedural distribution by right (you get what the culture has decide you are entitled to)(because of who you are)
Procedural distribution by contract (you get what you have agreed to get)
Procedural distribution by might (you get what others can't stop you from taking) (you get what you can take)
One thing that is obvious from this is that it is possible for something to be fair in one model and unfair in a different model. While it is possible for different models to produce the same results it is likely that they will produce different results. When people using different models come to different conclusions as to what is fair it is unlikely that the issue will be resolved to the satisfaction of both. When we do not feel that we have been treated fairly we call that injustice.
Because conflicting models of fairness exist it is not possible for everyone to feel fairly treated all the time, injustice is unavoidable. It is inevitable that someone will feel that they were not treated fairly. As long as there is more than one model of fairness this will never change.