I happen to think that Joel Hirschorn's article "WHY THE POLLUTION PREVENTION REVOLUTION FAILED-AND WHY IT ULTIMATELY WILL SUCCEED" http://www.p2pays.org/ref/39/38509.pdf#search=%22joel%20p2%20revolution%22 from the Winter 2000 P2 Review, is the most thought provoking piece on this topic that I've seen (though candidly, I don't pay much attention to "definition" articles, preferring to make my own definitions up as I need them).
Now, I disagree with much of what Joel said in that article, including his spin on Thomas Kuhn and Scientific Revolutions (the history and philosophy of science being a hobby of mine) -- but I think he put his ideas together in a thought provoking way that will encourage your students to think and develop their own ideas for what P2 "is" .
I actually would go so far as to say that it ought to be required reading for students of P2.
I'm sure there will be other opinions, but that's mine.
I have a request from a colleague asking the following:
I'm in the process of updating my syllabus (classes start in 1 1/2 weeks!). I'm realizing that I need a better article for one of my classes and thought I'd ask you for a recommendation. I'm looking for an article that focuses strictly on P2--what it is and what it is not. Most articles go into a plethora of P2 applications such as LCA, EMS, etc. I'm looking for a simple nuts and bolts piece that doesn't stray much from definition. Do you know of such an article?
Any good recommendations?