>A man from the past might consider the current mainstream democratic party "far/extreme left" Surely not. "Far left" would mean public ownership of the means

>A man from the past might consider the current mainstream democratic party "far/extreme left" Surely not. "Far left" would mean public ownership of the means of production and the abolition of the capitalist economic system. The Democratic party has never supported anything like that. It's centre-right party for the most part. More generally, you're presupposing that the only way to measure the extremity of an idea is by the number of people who hold it in a particular country at a particular moment in time. We can also bring to bear a global historical perspective and analysis of the content of the ideas themselves. Far right parties want to bring about the end of the very liberal democratic order in which ordinary left/right political debate can sensibly take place.