Cancer: complexity, causation, and systems biology
Commentators traditionally attribute the success of twentieth century biology to the assumption that complex biological phenomena and their causal pathways are reducible to elementary causal phenomena. Recently, however, some commentators challenge the sufficiency of reductionism for investiga- ting these phenomena. They propose antireductionism assumptions, like organicism or holism, to account for the complexity and causal pathways of biological phenomena. In this paper, I utilize contemporary cancer research as a case study to explore the role of reductionism and antireductionism for guiding scientific research. The chief paradigm directing contemporary cancer research is a modified somatic mutation theory, in which researchers presume mutated genes are responsible for causing cancer. An organicism approach (top-down causation), e.g. the tissue organization field theory, is contesting this traditional reductionism approach (bottom-up causation) to the disease. Today, however, a systems biology approach is superseding both of these approaches. In this approach, systems biologists explain cancer in terms of a heterogeneous complex network composed of bidirectional or reciprocal interactions (bottom-up and top-down causation combined) among various hierarchical levels including genes, cells, and tissue architecture, organism, and environment. In a concluding section, I discuss the question of whether systems biology represents a synthesis between reductionism and antireductionism.