Gidden's Duality of Medium and Outcome
Accorinding to Giddens, social structure is both medium and outcome. Structure
influences actions at the same time it is constituted by them.
From Giddens 1979:70:
Every process of action is a production of something new, a fresh act; but
at the same time all action exists in continuity with the past, which supplies
the means of its initiation. Structure is this not to be conceptualized
as a barrier to action, but as essentially involved in its production, even
in the most radical processes of change.