Nolan chart, 2d political spectrum.  Diagonal line indicates classical 1d left-right political spectrum.  See license below.
<ul><li><a href="//commons.wikimedia.org/wiki/File:Nolan-chart.svg" title="File:Nolan-chart.svg">Nolan-chart.svg</a>: Original uploader was <a href="https://en.wikipedia.org/wiki/User:SilverStar" class="extiw" title="en:User:SilverStar">SilverStar</a> at <a class="external text" href="https://en.wikipedia.org">en.wikipedia</a></li>
<li>derivative work: <a href="//commons.wikimedia.org/wiki/User:Pastorius" title="User:Pastorius">Pastorius</a> (<a href="//commons.wikimedia.org/wiki/User_talk:Pastorius" title="User talk:Pastorius"><span class="signature-talk">talk</span></a>)</li></ul>
CC BY 2.5
<ul><li><a href="//commons.wikimedia.org/wiki/File:Nolan-chart.svg" title="File:Nolan-chart.svg">Nolan-chart.svg</a></li></ul>