Overton window

The Overton window is the range of subjects and arguments politically acceptable to the mainstream population at a given time. It is also known as the window of discourse. The key to the concept is that the window changes over time; it can shift, shrink, or expand. It exemplifies "the slow evolution of societal values and norms". The term is named after the American policy analyst and former senior vice president at Mackinac Center for Public Policy, Joseph Overton, who proposed that the political viability of an idea depends mainly on whether it falls within an acceptability range, rather than on the individual preferences of politicians using the term or concept. According to Overton, the window frames the range of policies that a politician may recommend without appearing too extreme, in order to gain or keep public office given the climate of public opinion at that particular time.