Concepts and Theories, Methods and Reasons: Why Do the Children (Pretend) Play? Reply to Weisberg, Hirsh-Pasek, and Golinkoff (2013); Bergen (2013); and Walker and Gopnik (2013).

We greatly appreciate the astute comments on Lillard et al. (2013) and the opportunity to reply. Here we point out the importance of keeping conceptual distinctions clear regarding play, pretend play, and exploration. We also discuss methodological issues with play research. We end with speculation that if pretend play did not emerge because it was naturally selected (due to helping causal reasoning or some other developmentally important skill), perhaps it emerged as a by-product of 2 other selected behaviors: play fighting and language.