Either:

1) We go with the original meanings of the terms and:

“Right”= any political philosophy that can be traced to the late-18th/early-19th century French rightists. This would mean that the “right” would include monarchists, nationalists, and supremacists in addition to those who wish to preserve traditional values and those who oppose the redistribution of wealth. It would also include religious conservatives and those who are more comfortable with a partnership between church and state.

“Left”= any political philosophy that can be traced to the late-18th/early-19th century French leftists. This would mean that the “left” would include communists and socialists, in addition to those who believe that social progress and economic equality as goals that should be pursued by the state. It would also include those who see religion as having no place in the public square.

Or 2: We ignore the crazies on either end of the spectrum and use “Left” and “Right” as a shorthand for the policies of the Democratic and Republican parties respectively when we’re discussing American politics.

Most Americans opt for Option 2. Based on my blog-reading over the past year or so, it appears that those who inhabit the internet, both on the Right and the Left, are more comfortable with Option 1. What I find a bit disingenuous, however helpful it may be for book sales, is the Jonah Goldberg school of thought, in which any extremist movement whatsoever gets equated with the political philosophy of one’s opponents.