Defining "truth" and "virtue" is like nailing jelly to a wall; nobody agrees on what they are. That's why economists like Marx and Keynes didn't try to measure

Defining "truth" and "virtue" is like nailing jelly to a wall; nobody agrees on what they are. That's why economists like Marx and Keynes didn't try to measure them. Essentially nobody that aspires to any kind of rigour appeals to truth and virtue.