Swami Dayananda Saraswati (of Arsha Vidya Gurukulam), in his introduction to the Gita mentions various forms of dialogue.
Vaada: ".... a discussion involving two or more people who are interested in finding out the facts about a certain subject matter. They are all exploring. In this type of discussion, there is no teacher-student relationship. Each person is equally placed, even though one person may now a little more than the others about the subject matter. They are all interested in understanding. This kind of discussion among equals, any collective study among students, for example, is called "vaada" and is naturally healthy."
Swamiji says that there are two unhealthy types of dailgoue.
"One is the dialogue that takes place between two people who are already committed to different beliefs. Such a discussion, called "jalpa", is governed purely by each person's wit. Any discussion between two fanatics falls into this category. They are each convinced that the other person is totally wrong and tries to win the other over to his or her particular belief, even though there is no basis for the discussion."
He further says:
"...we cannot have a discussion based on such beliefs. Both of us may be wrong. A discussion between two people, both of whom are committed to certain beliefs, is purely a dialogue between two missionaries.....Each person always comes back with better arguments. Jalpa discussions are useless, they have no value."
He then mentions "vitandaa" where one person makes a statement and the other person always disagrees, merely because the other person said it. Such a discussion is also useless.
There is a student-teacher dialog, which he calls "samvaada", where the student gives the teacher the benefit of the doubt, because the student may not have understood fully.
What one hopes for in the blogsphere is vaada - which one might find e.g., on cosmicvariance.com. Unfortunately jalpa and even vitandaa dominate.
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