I get what you are saying, but the fact that the definition of what is moderate changes is a fact of life. Unfortunatly the only way to define the center is to define it by the extreme ends, just as the midpoint of a line can only be defined if you know where the line's endpoints are. I don't think saying something is extreme is necessarily a bad thing. There are times when being extreme (meaning no compromise is possible) is the right thing to be if the situation warrants. Likewise being a centrist on an issue means the issue is one where compromise is a likely option since the centrist can see benefits to both sides of the equation.

The truth is I'm very conservative on some issues and somewhat liberal on others. I'm willing to do a quick self evaluation. I'm not going to define the topics closely because that would bias the results. Its just based solely on my perception of where the extreme ends are.

liberal conservative
extreme-->very-->pretty-->somewhat-->center<--somewhat<--pretty<--very<--extreme
-4 -3 -2 -1 0 1 2 3 4

abortion - very conservative = 3
immigration - pretty liberal = -2
the war on terrorism - pretty conservative = 2
gay marriage - somewhat conservative = 1
universal healthcare - pretty conservative = 2
2nd ammendment - pretty conservative = 2
capital punishment - pretty liberal = -2
Euthenasia - very conservative = 3
Global Warming - somewhat conservative = 1
environmentalism - somewhat liberal = -1
National ID card - very conservative = 3

extreme = 44
very = 33
pretty = 22
somewhat = 11
centrist = 0

so I come out +12 to the conservative side.

I'd be curious to see how others would rate themselves on such a scale. Base it solely on your views of the ends if you are willing.