Wish I'd said that - November 8, 2017
"you cannot build prescriptions on mere knowledge of positive facts, however systematized and comprehensive. You need a goal as well... it is all very well to know how the world works... But unless you have some test whereby you can distinguish good from bad, desirable consequences from undesirable, you are without an essential constituent of a theory of policy. You are like the captain of a ship equipped with charts and compasses and all the means of propulsion and steering, but without an assigned destination. A theory of economic policy, in the sense of a body of precepts for action, must take its ultimate criterion from outside economics."
Lionel Robbins The Theory of Economic Policy in English Classical Political Economy pp. 176-77.