Johnson implies that to answer the question of why people moved to London, it’s not enough to look to the explicit, stated reasons individuals gave. Rather, social scientists must look to the broad, population-wide forces that may have pressured people to move to London without their being aware. For example, regardless of why people
say they moved to London, one might argue that the real reason for London’s growth was its monopoly on energy sources such as steam and coal, which “created” a new class of people to operate them and benefit from them (although Johnson doesn’t delve into detail about how this happened).