Being perfect economic thinkers doesn't mean they are all powerful. How does one go kill one guy without consequence? The only person this perfect economic thinker has access to is himself, and surely, he values his own life at infinity.
Ethics is an agreement between people in society, which cannot be captured via economic rationalism alone, but economic rationalism can take into account current ethics, as well as other actors' propensity for more or less ethics.
Ethics is an agreement between people in society, which cannot be captured via economic rationalism alone, but economic rationalism can take into account current ethics, as well as other actors' propensity for more or less ethics.