“No conversation, no change” is an important principle. Positive conversations between people in their own social networks tend to be preconditions for all sorts of social changes.
So, how to stimulate conversations? I can think of four ways:
1) Broadcast remarkable stories though the media (Chip and Dan Heath’s book Made to Stick covers this ground nicely).
2) Bring people together for facilitated discussions (field days, workshops at the like).
3) Recruit and train Popular Opinion Leaders. For example.
4) Conversation-starting initiatives and events.
There are a host of ways we can use events or public installations to start conversations. Here’s a list I developed for a recent project. It’s a PDF you can download to use in presentations.
http://www.enablingchange.com.au/conversation_starters.pdf

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