The Edge has published mini-essays by 119 "big thinkers" on their "most dangerous ideas" — fun reading.
The history of science is replete with discoveries
that were considered socially, morally, or emotionally
dangerous in their time; the Copernican and
Darwinian revolutions are the most obvious.
What is your dangerous idea? An idea you think
about (not necessarily one you originated)
that is dangerous not because it is assumed to be false, but because it might be true?