Whereas within the advanced economies the trend has been towards greater economic and social equality, in the developing world development is tending to create new economic and social inequalities. In a general way, the developed countries are more egalitarian than the undeveloped because all classes of the population are better integrated into economic and social life, whereas in the less developed countries the obstacles to equality in education and the many forms of discrimination prevent certain groups from competing equitably with the others.
The impulse to inequality that leads to discrimination is ancient in its origins. From the earliest periods of human existence, groups developed prejudices towards others and then, in their attempts to increase economic wealth, political power, or cultural and social prestige, discriminated against those whom they regarded as different or somehow inferior and thus not entitled to equal treatment.
A third of the world's population still produces and enjoys some 85% of the world's wealth; and the momentum of development is such that, in general, the more developed economies are still developing more rapidly than the less developed, thus further increasing disparities which are already grave. The most advanced economies still include undeveloped and even primitive sectors; virtually all the less developed economies now include highly advanced sectors: thus an increasing number of economies reproduce within themselves all the disparities and variants of the world picture.
Population growth in Rwanda, in Sudan, in El Salvador, in the slums of Lagos, in the highland hamlets of Chile, can devastate those places. Growing too fast may mean that they run short of cropland to feed themselves, of firewood to cook their food, of school desks and hospital beds. But population growth in those places doesn't devastate the planet. In contrast, those in the developed world easily absorb the modest annual increases in our population. These countries seems only a little more crowded with each passing decade in terms of our daily lives. You can still find a parking spot. But although the population of the USA increases by only about three million people a year, through births and immigration together, each of those three million new Americans will consume on average forty or fifty times as much as a person born in the Third World.
Whereas the structural upheavals that occur at the outset of economic development may increase differences and inequalities, the subsequent course of economic growth, accompanied by the spread of education, the extension of social security, the diffusion of ownership of the capital of large undertakings and the increase of income from work relative to income from property, contributes to a reduction of the general inequality of income distribution.
Human beings are empirically unequal in intelligence, skills, moral qualities, physique and beauty. It is only some religious or humanistic ideal that suggests an equality at some ontological level that transcends these empirical differences.
Equality is closely related to justice and freedom and these have to be balanced against one another. Equality cannot be the sole, comprehensive social ideal. Some social inequalities are necessary in a given society and period of history but should be justified in light of individual freedom, a just society and the common good.
Injustice arises when equals are treated unequally, and also when unequals are treated equally (Aristotle).