Gossen's Second Law, which
presumes that utility is at
least weakly quantified, is that in equilibrium an agent will
allocate expenditures so that the ratio of marginal utility to
price (marginal cost of acquisition) is equal across all goods and services.
U is utility
quantity of the i-th good or
the price of the i-th good or
Gossen's Third Law is that scarcity is a precondition for economic
Gossen, Hermann Heinrich; Die Entwicklung der Gesetze des
menschlichen Verkehrs und der daraus fließenden Regeln für
menschliches Handeln (1854). Translated into English as
The Laws of Human Relations and the Rules of Human Action
Derived Therefrom (1983) MIT Press, ISBN 0262070901.