 “Reductionism” in genetics can, on the one hand, refer to philosophical positions regarding theory reduction or reductive explanation. On the other hand, attitudes in biology and philosophy that are characterized by a preference for molecular over organismic accounts of biological phenomena or an emphasis on genes in explanations have been labeled “reductionist” (see entry on  reductionism in biology).  The latter, broader meaning overlaps with notions of “genetic determinism” and, more generally, “gene-centrism”. This section focuses on the former, technical meanings of “reduction”. The debate on reduction got contemporary philosophy of biology started around 1970 and is still on-going today (Vidal &amp; Teira 2020; Winther 2009). Theory reduction is most prominently articulated by Ernest Nagel (1961). Put very simply, on Nagel’s account, one theory reduces to another if the former can be logically derived from the latter, or, in terms of a nomological-deductive model of explanation, if the reducing theory explains the reduced theory. Since, on this view, the relation between theories is one between sets of statements, including, most importantly, laws or law-like generalizations, successful reduction also requires “bridge principles” or coordinating definitions, which indicate how the vocabularies (terms or predicates) of the two theories relate (see entry on  scientific reduction).