Every time someone suggests a new forum, Greg & co. have said that they would consider it if the need or enough interest had already been demonstrated. So just try having one formal debate, and see how it goes. If people are interested, they will start more debates and a need for a new forum may develop.
Have you seen the main page lately? I think there are quite enough forums in place as is. I like honestrosewater's idea. You can just set one up where ever is appropriate and make plans with the moderator of the particular forum. Maybe even post about it here to "advertise".
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