I wrote this in a comment on Google+ today, in a discussion of the death of Elinor Ostrom. I kind of like it, so I am putting it here, too:
Economic theory building proceeds by using abstractions to encapsulate what are thought to be important basic principles of interactive decision-making and then uses mathematics as a language for analysis to reach conclusions. There is also an empirical side that tries to find appropriate values for some of the parameters that are used in theorizing, with disputed success. The social side of human behavior is quite important in some parts of mathematical economic modeling; economic network analysis and the analysis of information diffusion and information cascades being some prominent examples that spring to mind.