Preserving the identification of a learning biological individual with a single agent across such modification requires increasingly ad hoc assignments of utility functions.

Why has classical game theory helped to predict non-human animal behavior more straightforwardly than it has done most human behavior? The answer is presumed to lie in different levels of complication amongst the relationships between auxiliary assumptions and phenomena. Ross (2005a) offers the following account. Utility-maximization and fitness-maximization problems are the domain of economics. Economic theory identifies the maximizing units—economic agents—with unchanging preference fields.