Here are some guidelines, offered by the Buddha of the Pali texts, for discussions among those intent on dhamma. I read these as an encouragement to avoid entangling topics such as politics, metaphysics, or sensual attractions, except with the intent of of helping each other towards non-entanglement. -Jake

AN 9.1 Sambodhi Sutta Self-awakening Translated from the Pali by Thanissaro Bhikkhu

"When a monk has admirable friends, admirable companions, admirable comrades, it is to be expected that he will get to hear at will, easily & without difficulty, talk that is truly sobering and conducive to the opening of awareness, i.e., talk on modesty, on contentment, on seclusion, on non-entanglement, on arousing persistence, on virtue, on concentration, on discernment, on release, and on the knowledge & vision of release."

AN 10.69 Kathavatthu Sutta Topics of Conversation Translated from the Pali by Thanissaro Bhikkhu

"It isn't right, monks, that sons of good families, on having gone forth out of faith from home to the homeless life, should get engaged in such topics of conversation, i.e., conversation about kings, robbers, & ministers of state; armies, alarms, & battles; food & drink; clothing, furniture, garlands, & scents; relatives; vehicles; villages, towns, cities, the countryside; women & heroes; the gossip of the street & the well; tales of the dead; tales of diversity, the creation of the world & of the sea; talk of whether things exist or not.

"There are these ten topics of [proper] conversation. Which ten? Talk on modesty, on contentment, on seclusion, on non-entanglement, on arousing persistence, on virtue, on concentration, on discernment, on release, and on the knowledge & vision of release. These are the ten topics of conversation. If you were to engage repeatedly in these ten topics of conversation, you would outshine even the sun & moon, so mighty, so powerful, to say nothing of the wanderers of other sects.