An introduction for those you who may not have heard much about the concept https://en.wikipedia.org/wiki/Horseshoe_theory
Like with most things, it's complicated but I do think there are certain core inclinations, tendencies, and a general uniting ethos between the far left and far right that does suggest taking horseshoe theory seriously. I've laid them out below.
- A bone deep rejection of 'the system' with the system being liberal democratic capitalism of one type or another. The far left/lemmygrad and far Right both feel that the liberal democratic market capitalist societies are empty. People are happy with their Netflix and playing games on their phones and taking pictures of their food and posting it on Instagram. In contrast, the far left and the far Right hunger for revolutionary drama. Accordingly, they abhor legislative incrementalism and love mass street protests which destabilize 'the system.'
- They both hate the center-left and center-right more than each other. Listen to the way the far left talks about Biden or the way the far Right talks about Romney.
- They both regularly apologize for anti-Western dictators. The far Left prefers to defend Maduro, the far Right Putin. But they converge on Assad.
- Vaccine 'skepticism' and a general distrust of science as hopelessly tainted by 'big pharma' Right-wing examples of this are endless but see Russell Brand showing the far Left in 'now we can't even question it' mode here. He also declares mandatory vaccination constitutes 'apartheid' So does Madison Crawthorne (or however you spell https://www.youtube.com/watch?v=YfxnKgCN3OY](https://www.youtube.com/watch?v=YfxnKgCN3OY)
- Unhinged hostility towards Israel and anti-Semitic language (as distinct from rejecting the toxic authoritarianism of Netanyahu and supporting a humane two-state solution)
- Anti-globalization. Both far Left and far Right claim globalization has impoverished us and made the world shittier for everyone but the very Rich. If you take a Trump or Sanders speech on trade, you'd struggle to tell them apart (well the strange capitalization would give Trump away but yeah). While center-right and center-left see the world becoming more like America as a generally good thing, the far Left and far Right have nothing but contempt for 'Americanization.'
There's probably many, many more. Curious to hear your thoughts.
I don't think this argument will get you many friends here ;)
It is anyway a false comparison. Its a bit like oil and water... of course if you want to look for similarities you can find them (both are liquids, you can drown in them, etc.), but in what really matters they are nothing alike and will actively repulse each other.
Of course you have the other dimension of the political compass and authoritarians are often more alike than they wish themselves, but that has more to do with the means employed than actual ideological similarities.
And last but not least, I totally disagree on point 2. People do get more heated about their more closely related out-group, but that mainly because those are not seen as a totally lost cause, while the very opposite ideological spectrum is not really worth to even discuss as it is so obviously just "bad".
However, where the argument gets more muddy is when proponents on either side think they can "win over" supporters by taking over and seemingly subvert arguments of the other side. That is a common fallacy some people make, and it never resulted in a good outcome.