Increasingly Radical Claims about Heredity and Fitness Eugene Earnshaw-Whyte* y On the classical account of evolution by natural selection (ENS) found in Lewontin and many subsequent authors, ENS is conceived as involving three key ingredients: pheno- typic variation, fitness differences, and heredity. Through the analysis of three problem cases involving heredity, I argue that the classical conception is substantially flawed, showing that heredity is not required for selection. I consider further problems with the classical account of ENS arising from conflations between three distinct senses of the central concept of ‘fitness’ and offer an alternative to the classical conception of ENS involving the interaction of distinct evolutionary mechanisms. 1. Introduction. Evolution by natural selection (ENS) is often conceived as requiring three essential elements: variation, heredity, and fitness differences. Lewontin (1970) provides perhaps the most well-known formulation of this ‘classical account’. For Lewontin, the three components are as follows: 1. Different individuals in a population have different morphologies, physiologies, and behaviors (phenotypic variation). 2. Different phenotypes have different rates of survival and reproduction in different environments (differential fitness). 3. There is a correlation between parents and offspring in the contribu- tion of each to future generations (fitness is heritable). While subsequent authors have attempted to refine and improve this account, its essentials are widely accepted (Hull 1980; Sober 1984; Endler 1986; Ridley 1996; Stephens 2004; Okasha 2006). On this view, these three Received January 2011; revised July 2011. *To contact the author, please write to: 8 Wellesley Street East, Apartment 703, Toronto, ON M4Y 3B2, Canada; e-mail: malefax@rogers.com. yI would like to thank Denis Walsh, Mohan Matthen, Jean Gayon, and my anonymous reviewers for their helpful suggestions and comments. Philosophy of Science, 79 (July 2012) pp. 396–412. 0031-8248/2012/7903-0005$10.00 Copyright 2012 by the Philosophy of Science Association. All rights reserved. 396