urbanism defined

Following a very interesting lunchtime presentation by the chairman of the Academy of Urbanism , a question that was asked stayed with me. How do we define Urbanism.
The very skilled answer that came from John Thompson was that urbanism is space-place-life.
This is a very simple but powerful triptych that can be analysed and interpreted in a variety of ways. urbanism is the place created by defining space that affects life. And by affecting i mean change, generate, or even destroy.
Is it just another "tag" that defines a specific trend. if we accept the interpretation as space -place-life this by default makes all architects urbanists.
to be continued