Overton Window

"A toast...to high treason. That's what these men were committing when they signed the Declaration. Had we lost the war, they would have been hanged, beheaded, drawn and quartered, and--my personal favorite, had their entrails cut out and BURNED!"
--Benjamin Franklin Gates (National Treasure)

The Overton Window conceptualizes the range of politically acceptable policies at a given time. Developed by policy analyst Joseph Overton, the model can be seen as representing the window of opportunity of sorts for politicians. 

In the model, all possible government policies fall along a single vertical scale. Toward the upper end of the scale are policies that reduce government regulation and expand personal freedom. Toward the lower end of the scale are policies that increase government regulation and restrict personal freedom.

At any given time, only a subset of these possibilities is widely seen as legitimate. This subset constitutes the Overton Window. Politicians are likely to pursue policies inside the window. If they stray outside the window to champion other ideas, then politicians are likely to be viewed as too radical or extreme to gain or keep public office.

An interesting and perhaps counterintuitive feature of the theory is its premise that politicians are able to detect the boundaries of acceptability defined by the window but possess limited capacity for altering those boundaries. Instead, intellectuals, social movements, advocacy groups, and other shapers of popular opinion are more likely to alter the window. 

An exception might lie in charismatic political leaders who behave in manners that capture the hearts and minds of the people.

Because the battle between force and freedom is as old as society itself, the boundaries of the Overton Window are in a constant state of flux. As such, politicians who operate near the edges of the window risk public opinion turning against them if the window moves away from the policies that they promote.