Comment by jonah
Related: Overton Window
"The Overton window is the range of policies politically acceptable to the mainstream population at a given time. It is also known as the window of discourse.
The term is named after the American policy analyst Joseph Overton, who proposed that an idea's political viability depends mainly on whether it falls within this range, rather than on politicians' individual preferences.[2][3] According to Overton, the window frames the range of policies that a politician can recommend without appearing too extreme to gain or keep public office given the climate of public opinion at that time."
While originally about politics, I feel it can be applied to many other aspects of humanity and maybe is just a specialized form of the normalization of deviance.