Commonly discussed in radical political circles is the Overton window (also called the window of discourse), which is typically defined as the range of subjects and arguments—public ideas—politically acceptable to the mainstream population at a given time. The Overton window varies over time (either by shifting, shrinking, and/or expanding), thereby demonstrating the gradual evolution of societal norms and values. Less well-known is that political commentator Joshua Trevino has hypothesized that the political acceptability component of the Overton window can be subdivided into six significant and separately identifiable degrees. These degrees of political acceptability are, from least copacetic to most copacetic, as follows: unthinkable, radical, acceptable, sensible, popular, and policy.