I was drawn to the question of heresy by reading Augustine’s Confessions, and Peter Brown’s masterful biography, Augustine of Hippo (1967, 2000). For instance, comparing Augustine and Pelagius, he writes
“The two men disagreed radically on an issue that is still relevant, and where the basic lines of division have remained the same: on the nature and sources of a fully good, creative action. How could this rare thing happen? For one person, a good action could man one that fulfilled successfully certain conditions of behavior, for another, one that marked the culmination of an inner evolution. The first view, was roughly that of Pelagius; the second, that of Augustine.”
My guess is that the choice between solutions that leads to a perspective being labeled heresy is necessary for a consistent set of beliefs, but that something is lost when the choice is made. I’m reminded of Isaiah Berlin’s approach to conflicts of values, summed up thus by John Gray in an interview with Alan Saunders on the Philosopher’s Zone (Australian Radio National, 6 June 2009)
“ . . . the idea that some fundamental concepts of human values are intractable, rationally intractable, in the sense that first of all they can't be resolved without some important loss, and secondly reason is very important in thinking about these conflicts, and then being clear about what they are, what they're between and what's at stake in them. [E]qually reasonable people can come to different judgments as to what ought to be done, so certain types of conflict of value are intractable. . . . So this idea of a kind of fundamental and intractable moral scarcity if you like in human life, such that there have been and there will always be intractable, the conflicts of values, and we can resolve them more or less intelligently in particular contexts that can be more or less skillful and intelligent and reasonable settlements of these conflicts, but they can never be overcome or left behind.”
Such differences may point to a conflict between incommensurable world views. For example, in an article about “relativity deniers”, (Einstein's sceptics: Who were the relativity deniers?, New Scientist 18 November 2010, subscription required) Milena Wazeck explains,
"Einstein's opponents were seriously concerned about the future of science. They did not simply disagree with the theory of general relativity; they opposed the new foundations of physics altogether. The increasingly mathematical approach of theoretical physics collided with the then widely held view that science is essentially simple mechanics, comprehensible to every educated layperson."
I would not be at all surprised if there is at least something like this at play in the argument over climate change; opponents have been all but branded as heretics, and there is religious fervor on both sides.