Abstract
In its most part, this article is a critique of three of the most common ways of defining egalitarianism: 1) egalitarianism is a trend of thought in political philosophy to which belong (all) philosophers who support a form of equality, whatever it may be, between all members of a community; 2) egalitarianism is a trend of thought in political philosophy which has as a ultimate or foundational value equality in the abstract sense of treating all people as equals; and 3) egalitarianism is a trend of thought in political philosophy that defends equality in the distribution of certain goods or resources. In the last part of the article I defend the idea that egalitarianism is much better described as a trend of thought in political philosophy that defends a substantial equality between all members of a community as a ultimate principle of social justice.