The horseshoe theory in political science asserts that rather than the far left and the far right being at opposite and opposing ends of a linear political continuum, they in fact closely resemble one another, much like the ends of a horseshoe.
The earliest use of the term "horse shoe theory" appears to be from Jean-Pierre Faye's 2002 book Le Siècle des idéologies. The horseshoe theory has been criticized not just by people on both ends of the political spectrum who oppose being grouped with those they consider to be their polar opposites but also by those who see horseshoe theory as oversimplifying political ideologies and as ignoring fundamental differences between them.
Horseshoe Theory is the title of a 2017 romantic comedy short film by Jonathan Daniel Brown in which an Islamic State Jihadist and a white supremacist who meet following a weapons deal over the internet and fall in love?! after discovering how much they share in common?!
'Horseshoe Theory' Is Nonsense – The Far Right And Far Left Have Little In Common