Abstract

S. Oyama’s prominent account of the Parity Thesis states that one cannot distinguish in a meaningful way between nature-based (i.e. gene-based) and nurture-based (i.e. environment-based) characteristics in development because the information necessary for the resulting characteristics is contained at both levels. Oyama as well as P. E. Griffiths and K. Stotz argue that the Parity Thesis has far-reaching implications for developmental psychology in that both nativist and interactionist developmental accounts of psychological capacities that presuppose a substantial nature/nurture dichotomy are inadequate. We argue that well-motivated abandoning of the nature/nurture dichotomy, as advocated in converging versions of the Parity Thesis in biology, does not necessarily entail abandoning the distinction between biologically given abilities necessary for the development of higher psychological capacities and the learning process they enable. Thus, contrary to the claims of the aforementioned authors, developmental psychologists need not discard a substantial distinction between innate (biologically given) characteristics and those acquired by learning, even if they accept the Parity Thesis. We suggest a two-stage account of development: the first stage is maturational and involves interaction of genetic, epigenetic and environmental causes, resulting in the endogenous biological ‘machinery’ (e.g. language acquisition device), responsible for learning in the subsequent stage of the developmental process by determining the organism’s responses to the environment. This account retains the crux of nativism (the endogenous biological structure determines the way the organism learns/responds to an environment) whilst adopting the developmentalist view of biology by characterizing environments as distinctly different in terms of structure and function in two developmental stages