The terms left, right, con, lib are fairly fluid throughout recent history so as to make origins fairly meaningless, though quite interesting just not something you can meaningfully trace briefly. Quick Answer for left/right: French Revolution. Liberalism traces mostly to John Locke, and in the US that's where things break down because both sides during whatever era were big fans of that sort of Liberalism and not fans of traditional conservatism of the founding era... hereditary ruler ship and state churches. During the civil war both sides claimed to be conservative, and this continued afterwards to suppress the liberals of that era, the radical republicans, who most modern people, left or right, would generally agree with on a lot more than the others of that era. Things started to kinda align to modern in 1896 but it wobbles around a lot and it's tricky to pin down exact definitions since parties try to attract or keep certain factions, those factions generally have specific views but not necessarily on everything.



Bad news is you really need the details, as mentioned each of the factions usually has either a specific-event origin or a specific philosophy, the former usually are anti-something, initially anyway, whereas the latter usually have a book or two that runs "Let's start with the following assumptions and..." and they act very differently. The former also tends to serve as a big recruiting ground for parties, which generally are very loose coalitions. Not sure who does it for the Dems, but the GOP binding glue is the Fusionism Faction, which picks its name from trying to fuse together the various surviving right-wing factions from the 60s and 70s.



Oh, definitely, this is actually one of those topics that can be as controversial as abortion, as people try to claim this or that heroic leader of the past and shove this tyrant onto the others. Hopefully no one will do that this time but I doubt it and for all I know I might have done it even though I was trying to resist the urge to do so. Ironically you can even start verbal bloodbaths inside a party over stuff like this, Sunni vs Shiite or Protestant vs Catholic as opposed to the Crusades.