 The idea of levels has also figured prominently into arguments for antireductionism and pluralism. In his classic treatise, Philip Kitcher (1984) elevates the level concept to a centerpiece of the antireductionist position. According to Kitcher, the reductionist aspiration of reducing classical Mendelian to molecular genetics will not pan out because molecular constituents do not capture the causal relations between Mendelian constituents (e.g., chromosomes) and heritable traits. The reason for this is that the cytological processes that form the basis for Mendelian patterns of heredity (such as meiosis) form a natural kind that cannot be delineated at the molecular level (1984: 349; Brigandt 2013: 76). Importantly, Kitcher grounds this in the structure of the world as captured by the levels concept: 