The relation between Cartesian dualism and the developmental dualism o
f the nature-nurture dichotomy is discussed, with special attention to
the treatment of subjectivity and agency. I argue that causal explana
tion need not drive out active subjects, as it so often seems to, and
that it is especially questionable to attempt to solve questions of mo
ral responsibility by weighing biological against environmental causes
, or causes in general against reasons. A developmental systems perspe
ctive provides a way of seeing subjectivity as both constructed and na
tural. Aspects of persons cannot then be attributed to biology or cult
ure, and responsibility is a matter not of independence from causal in
fluence, but of action and accountability in a social world.