Justice is the legal or philosophical theory by which fairness is administered. The concept of justice differs in every culture. An early theory of justice was set out by the Ancient Greek philosopher Plato in his work The Republic. Advocates of divine command theory say that justice issues from God. In the 17th century, theorists like John Locke advocated natural rights as a derivative of justice. Thinkers in the social contract tradition state that justice is derived from the mutual agreement of everyone concerned. In the 19th century, utilitarian thinkers including John Stuart Mill said that justice is what has the best consequences. Theories of distributive justice concern what is distributed, between whom they are to be distributed, and what is the proper distribution. Egalitarians state that justice can only exist within the coordinates of equality. John Rawls used a theory of social contract to show that justice, and especially distributive justice, is a form of fairness. Property rights theorists (like Robert Nozick) take a deontological view of distributive justice and state that property rights-based justice maximizes the overall wealth of an economic system. Theories of retributive justice are concerned with punishment for wrongdoing. Restorative justice (also sometimes called "reparative justice") is an approach to justice that focuses on restoring what is good, and necessarily focuses on the needs of victims and offenders.
Living organisms including humans are social when they live collectively in interacting populations, whether they are aware of it, and whether the interaction is voluntary or involuntary.
Social justice is a concept of fair and just relations between the individual and society. This is measured by the explicit and tacit terms for the distribution of wealth, opportunities for personal activity and social privileges. In Western as well as in older Asian cultures, the concept of social justice has often referred to the process of ensuring that individuals fulfill their societal roles and receive what was their due from society. In the current global grassroots movements for social justice, the emphasis has been on the breaking of barriers for social mobility, the creation of safety nets and economic justice.
Researchers have developed sophisticated computer models that simulate the fate of carbon dioxide (CO2) injected and stored in deep geological formations.