Emerging Epistemologies in life sciences

There is a tendency in scientific practice to elaborate complex and multilevel models to accountfor biological dynamics. Systemic approaches have been advocated to account for such phenomenology,so that models often emerge as networks of dynamic interactions with elementsthat acquire a specific explanatory relevance depending on the scientific question. However,what actually characterizes such systemic accounts is not ultimately clarified. The thesis Idefend in this paper are a) that the process of attribution of relevance in explanatory terms is akey epistemological issue in scientific practice and b) that such process implies acknowledgingan ontological feature of biological systems and of their regulation, i.e. their nested inter-levelstratification. This also clarifies how natural phenomena can be addressed at different levelsand understood through a systemic approach.