Okay, the concepts are relative by nature (arguments about the two-dimensional nature of the left-right axis notwithstanding). In that case, place the concepts (or perhaps the individual ideologies that bundle the concepts) on a distribution and draw a line near the perceived median. That's the sort of thing you see in some poly-sci texts, and it makes sense.

My point was that it is a mistake to place people on a left-right distribution based on their positions and call the people in, for example, the first quartile the "far left."

> I think of it as relative to other americans, not to the rest of the world, and especially not relative to some absolute concept of right and left

The problem is, applied universally this approach of quantifying things would make it appear as though every place possesses the same diversity of political thought, whether you're talking about Europe, the United States, or North Korea. This is simply not the truth.

edit: another problem is that it can cause people whose views are much closer together than, for example, socialists vs fascists, to view each other as being on opposite ends of an ideological spectrum and combatants in a bitter ideological struggle, even though that's objectively ridiculous. Remind you of anyplace?