Beliefs are our guiding principles and we use them to make sense of the world. Some beliefs are generalizations about the world we live in. For instance, when I say, "when entering from the outside of a house or room, doors open inward and the door knob is on the left", you probably have to think about it, because, after opening doors from a young age, your mind has created a belief and then generalized it so that it doesn’t have to think about it. I knew a person that was left-handed and had his doors open outward.