The issue is not that we disagree with each other, disagreements have been going on since the dawn of human history. More fundamental, is how we express that disagreement. In academia disagreement can result in no-tenure-for-me because members of the ruling paradigm do not want to give up their comfy old theory and the grant money. In Buddhism, there are like problems which have been going on for well over two millennia. Sometimes in the past, disagreements over what the Buddha taught and what he didn’t teach got really nasty. Some debates in the past became violent.

A famous debate that took place in Tibet in 792 A.D. between Chinese Zen master Ho-shang Mahayana and and Indian master Kamalashila in which the winner's form of Buddhism would be officially sponsored. The disagreement was, supposedly, over Zen's sudden enlightenment tradition and the gradual tradition of Indian Buddhism which, I must inject, is a terrible oversimplification.

According to some records Ho-shang Mahayana was defeated by Kamalashila which is called the Samye Debate. Again, the records say that Ho-shang Mahayana asserted that not thinking anything in the mind is the profound path to enlightenment. In other words, having a blank mind is the goal of Zen! But this is obviously a perverse interpretation, one which was self-serving for the supporters of Indian master Kamalashila. However, judging by one of the manuscripts found at Tun-huang, the Samten Migdron, a Tibetan document, it lists the sudden enlightenment teachings of Ho-shang Mahayana as being higher than the gradualist teaching which was represented by Kamalashila while Tantra and Dzogchen are the highest both, incidentally, subscribing to instant realization. I should mention that the debate wasn't bloodless.

"As it turned out, proponents of both sides seem to have been much alarmed at the other's teachings, and after the debate, students of both parties are recorded as having committed suicide in protest at the verdicts reached. One named Nan sa mi cut his flesh into pieces. Two Tibetan crushed their genitals, and one of the Chinese teachers, called Mem go, set his head alight and died. Some of the Chinese party are said to have decided to assassinate members of the Indian. Chinese members claimed the Indians had already made a similar plan. In the dPao gtsug p'ren ba manuscript, it was recorded that the Chinese Chaan teacher hid some of his school's texts in a rock lest they all be killed and the teachings forgotten. It is said that three of these texts were the Lankavatara Sutra, the Bodhidharma Meditation Sutra and The Prajna Paramita" (Shifu Nagaboshi Tomio, The Bodhisattva Warriors, p. 444).