"Rational behavior" is behavior that maximizes utility by concurrently maximizing benefits and minimizing costs. It is called "rational" under the assumption that such self-interested behavior befits any rational being. The term is frequently used in economics.
Sometimes it is called instrumental rationality:
- Instrumental rationality (or “means-end rationality”) consists in choosing the correct means to attain one’s actual goals, given one’s actual beliefs. This is the kind of rationality that economists generally assume in explaining human behavior.
The rationality in this case is morally neutral: it may prevent a person from anti-social behavior by reminding him of the attendant costs (i.e. punishment), but may encourage "immoral" acts if an individual views them as the most efficient choice in his circumstances. Rational behavior is further complicated when utility interdependence is taken into consideration - i.e., when the individual seeks not only utility for himself, but also utility for others, such as his loved ones.