The somatic mutation theory (SMT) of cancer has been and remains the prevalent theory attempting to explain how neoplasms arise and progress. This theory proposes that cancer is a clonal, cell‐based disease, and implicitly assumes that quiescence is the default state of cells in multicellular organisms. The SMT has not been rigorously tested, and several lines of evidence raise questions that are not addressed by this theory. Herein, we propose experimental strategies that may validate the SMT. We also call attention (...) to an alternative theory of carcinogenesis, the tissue organization field theory (TOFT), which posits that cancer is a tissue‐based disease and that proliferation is the default state of all cells. Based on epistemological and experimental evidence, we argue that the TOFT compellingly explains carcinogenesis, while placing it within an evolutionarily relevant context.magnified imagemagnified imageAna Soto and Carlos Sonnenschein are at Tufts University School of Medicine, Boston, MA, USA. (shrink)