"Toward a New Vision: Race, Class, and Gender as Categories

Essay

"Toward a New Vision: Race, Class, and Gender as Categories of Analysis and Connection" by Patricia Hill Collins
Collins advocates a new vision of how race, class, and gender operate to structure inequality in daily life. Rather than focusing on their additive effects, she advances a perspective in which they are seen as interlocking, with each having roots in experiences with institutions, interactions, and the symbolic governing of daily life.
-What does Collins mean when saying "additive" effects of race, class, and gender are unable to explain patterns of domination and subordination?