Does the Net promote echo-chambers?

Steven Johnson questions the
conventional wisdom that the Net fragments us into like-minded
micro-communities.  (FYI, the seminal elaboration of this
viewpoint is Andrew Shapiro’s The Control Revolution.) 

I generally agree with Johnson’s view.  The Net gives us many
tools to filter information and to spend our time in closed
communities.  But at the same time, it exposes us to far more
diversity than any previous medium.  Those filters are never
perfect.  And there is a countervailing pressure toward
aggregation, which works against the fragmenting effects of
filters.  Google and Yahoo aren’t echo chambers, because their
value comes from their breadth and scale. 

Furthermore, even when online communities and information sources are
narrowly tailored to a specific viewpoint, that doesn’t mean the people
participating in them are hermetically walled off from one
another.  Communities overlap.  If I’m a dog owner, a
libertarian, and a fan of Sex and the City (for the record, I’m none of
the above), chances are the people and content I interact with will
differ from me along at least one of those dimensions.  Some
people may vote based on a single issue, but no one is ultimately
defined by a single interest.  The more specialized the commuity,
the more likely its members will differ on other matters. 
Spill-over is inevitable.

The final point is that the Net is still largely an open
platform.  There is always room for another community or
information source.  Traditional media has never been open in the
same way.  With consolidation and the rise of politically
polarized news, it is becoming even less so.  At a dinner the
other night, I talked with Mark Walsh, a former exec at VerticalNet and
AOL, and technology advisor to the Democratic Party.  He is
launching a liberal talk radio network called Progress Media in eight
cities in March.  Perhaps, on radio at least, there is still some
room to challenge the dominant opinion current.