Man says that in social sciences, truth is derived through 'praxeological' reasoning, not empirical observation. i.e. you *deduce* and *reason out* truths rather than *calculate* or *observe* them. Unlike natural sciences like physics, which rely on controlled experiments and isolated observation, social sciences like economics is about studying the laws of human action independent of data or sources. Controlled experiments in human societies is not possible, as there are people who interact with each other and make hundreds of decisions based on hundreds of values and desires that are all unknowable. Society is uncontrollable and unplannable. So one can't understand it using statistics, equations and math models.