  2007 was the first international congress on the ?square of oppositions?. A
first attempt to structure debate using n-opposition theory was presented along
with the results of a first experiment on the web. Our proposal for this paper
is to define relations between arguments through a structure of opposition
(square of oppositions is one structure of opposition). We will be trying to
answer the following questions: How to organize debates on the web 2.0? How to
structure them in a logical way? What is the role of n-opposition theory, in
this context? We present in this paper results of three experiments
(Betapolitique 2007, ECAP 2008, Intermed 2008).
