"I'll show you politics in America. Here it is, right here: "I think the puppet on the right shares my beliefs.' "I think the puppet on the left is more to my liking.' "Hey, wait a minute, there's one guy holding out both puppets!'" -- Bill Hicks
In 1789, members of France's new National Assembly took up sides in the debate over whether to support the King or the Revolution. Champions of the King sat to the right of the assembly president, with fans of the Revolution to his left. Thus was born from an arbitrary seating plan the concept of a political spectrum that ranges from extreme radicalism on the "Left" to reactionary conservatism on the "Right."
A comprehensive history of the terms and their use over the last two-plus centuries may exist, but I have been unable to find one. Worse, I can't really locate a satisfactory definition. The general understanding, in the United States at least, is that "Left" is roughly synonymous with "liberal" and "Democrat," while "Right" goes with "conservative" and "Republican." This is too loose to be useful. It begs the question: Very well, then, what is a liberal Democrat, or a conservative Republican?
Here are the Cambridge Dictionary's definitions of political Left and Right:
"The Left: The political groups that believe wealth and power should be shared between all parts of society."
"The Right: Political parties or people that have traditional opinions, and who believe in low taxes, private ownership of property and industry, and less help for the poor."
The problems here are many. What if I believe that low taxes and private ownership (principles of the Right) lead to wealth and power being shared between all parts of society (the goal of the Left)? What if I hold to traditional opinions, but believe that one of those traditional opinions is that I should help the poor?
The terms are sometimes used in a more social than political context, made synonymous with "open-minded" (the Left) and "close-minded" (the Right).