Pluralism is a framework of interaction in which groups show sufficient respect and tolerance of each other that they fruitfully coexist and interact without conflict or assimilation.
Pluralism is arguably one of the most important features of modern societies and social groups, and may be a key driver of progress in science, society and economic development.
In authoritarian or oligarchic societies power is tightly-held and by implication decision-making rests with the few. In a pluralistic society or group power and decision-making (and the ownership of the results of exercising power and taking decisions) is more diffused and there is more widespread participation and more feeling of commitment. Whether in a firm, a political body or an economy this commitment and participation can make all the difference to the quality of outcomes.
Arguably the open, pluralistic structure of science is a major factor in allowing the rapid growth of knowledge, and it is almost unarguable that the growth of knowledge leads to increased human welfare e.g. via more rapid economic growth (via increased productivity) or via improvements in medical technology.
See also: religious pluralism