I understand humanism to be the meta-ethical view that there exist discoverable (nonmoral) truths about the human condition, that is, about what it means to be human. We might think that as long as I believe I am realizing my unique human potential, I cannot be reasonably contradicted. Yet when we consider systemic oppression, this is unlikely. Systemic oppression makes dehumanizing conditions and treatment seem reasonable. In this paper, I consider the nature of understanding-drawing in particular upon recent defenses of realism in the philosophy of science-and argue that humanism makes sense if we recognize more thoroughly the role of cause and effect in practical deliberation. By this I mean the cause-and-effect relation between mind and body and between minds, bodies, and the world. Three philosophical sources-Marxism, Buddhism and Christianity-show what this might mean, as I indicate in the second half of the paper. [ABSTRACT FROM AUTHOR]