Tradition is socially contingent.  It is actions, patterns, customs, habits, repeated in time such that they are seen to represent a continuity of attitudes and values. Tradition is important: it tells us that we are part of a stable world.
In tradition, events and circumstances of the past are recreated.  They are made to endure, or to arise again.  The idea that tradition is true to history is therefore false: in recreating the past, the past is re-created. 
The role of architecture in securing tradition is in its physical resistance to re-formation: it is present, and to change it requires effort and exertion.  It is a bulwark against our own impermanence.  In a constantly renewed and re-created environment, the architectural frame is a point of fixity.  It seems continuous and unchanging.  It lasts. 
Its meaning, though, can change.  Architectural languages are always subject to interpretation; their readings are socially, politically and culturally formed, and can thus be re-formed. 

The most meaningful and enduring sense of tradition in architecture is therefore in the small things – the elements of buildings which speak to our instincts and allow us to inhabit them in enduring ways.  The rhythm of footsteps on stairs, the security of a mass of wall against your back, the exhilaration of a revealed view.  It is tradition in the simplest sense: evidence that people have lived here before in this same way.