Breaking down levels of biological organization.

Understanding biological behaviours implies explaining the organization of living beings. Cancer compromises the normal structure and function of tissues, cells, and genes so that it appears as a multilevel phenomenon. The biology of cancer is thus giving us interesting insights on the organization of a biological system and its hierarchical phenomenology. My thesis is that understanding the dynamics of this biological system implies making explicit features of a non-univocal notion of organization and two different dimensions of the parts-whole dependence, i.e. different modes of causality in maintaining levels of organization. The argument follows the analysis of some features of the biology of cancer. Convergence of interpretative models towards an operational account of levels, i.e. through concepts that focus on the dynamic control of levels' organization, contributes to this analysis too. A multi-unity perspective replaces the parts-whole perspective to explain what conditions the hierarchical control of biological behaviours depends on and how that dependency works.