Isn&#x27;t his point that there is a sort of uncertainty principle in economics?  For example when you study people they behave differently and furthermore as soon as they think that you think that they will behave in a certain way they may well behave differently -- especially if there is financial gain at stake for changing their behaviour.  As you say this all derives from the biggest problem with all the social sciences people are not rational actors and any mathematical model has to encapsulate real human behaviour.