What defines our society & culture?

How do the extremes define the norms?

@Winterwanderer: its a constant pull between one side or another on any given subject. theres black and white and a range of grey areas in between. for example in my society most people used to think being gay was wrong, even illegal.. now we have really loud and proud gays on one side, homophobes and extreme religion on the other and the vast majority of people in the middle who are 'ok' with gay people or hence the laws that protect them are falling into a middle ground of everyones beliefs.

But those are more beliefs than norms, & I somewhat agree, our cultural beliefs are often defined by the extremes, though I'm not sure the middle ground is defined by this, I feel like in modern society the middle ground became less defined & less populated when people shifted their weight further into their extremes. I've met a very miniscule amount of true moderates, most people either siding one way or another.