 For this reason, it helps to think of the idea of equality or inequality, in the context of social justice, not as a single principle, but as a complex group of principles forming the basic core of today’s egalitarianism. Different principles yield different answers. Both equality and inequality are complex and multifaceted concepts (Temkin 1993, chap. 2). In any real historical context, it is clear that no single notion of equality can sweep the field (Rae 1981, p. 132). Many egalitarians concede that much of our discussion of the concept is vague, but they believe there is also a common underlying strain of important moral concerns implicit in it (Williams 1973). Above all, it serves to remind us of our common humanity, despite various differences (cf. 2.3. below). In this sense, egalitarianism is often thought of as a single, coherent normative doctrine that embraces a variety of principles. Following the introduction of different principles and theories of equality, the discussion will return in the last section to the question how best to define egalitarianism and its core value.