Basically, having only these two ideologies (conservative and liberal), is like living in a house with two other people, one who is always and only in favor of running the air conditioner, and another who is always and only in favor of running the heater.
So, in July, the first is saying "We need the Air Conditioner !", and the second is saying "We need the Heater !".
Then, in January, the first is saying "We need the Air Conditioner !", and the second is saying "We need the Heater !".