Often assumptions are made which lead to equations in x which cannot be solved "rationally," i.e.
I buy something because I have certain assumptions about how much happiness it will bring me.
There is no subject of human study which may not be at some time or other of economic significance, and anything which affects the character, the ideals or the environment of man may make it necessary to modify our assumptions and our reasoning with regard to his conduct in economic affairs.
These assumptions, however, were fanciful.
He also gives us " natural law " 2 - a Stoic inheritance, preserving the form of an idealist appeal to systematic requirements of reason, while practically limiting its assumptions to those of intuitionalism.