Decisions and plans made by others... [can be judged to be] quantitatively at least as important as the primary uncertainty arising from random acts … - Tjalling Koopmans

We look upon economic theory as a sequence of conceptual models that seek to express in simplified form different aspects of an always more complicated reality.

According to a frequently cited definition, economics is the study of “best use of scarce resources.” The definition is incomplete. “Second best” use of resources, and outright wasteful uses, have equal claim to attention. They are the other side of the coin.

While it was long possible and sometimes tempting for physicists to deny the usefulness of the molecular hypothesis, we economists have the good luck of being some of the ‘molecules’ of economic life ourselves, and of having the possibility through human contacts to study the behavior of other ‘molecules’.