I think our beliefs are an important part of what makes us human.
A belief is an assertion, assumption, or expectation, and the collection of beliefs form a foundation for our thoughts and our actions. A belief is essentially a thought which we feel is true, so it requires both thinking and feeling to hold a belief. It can be conscious, such as something we have learned, or it can be subconscious, such as something we have always known and felt and seem to do so without thinking.
Our belief systems are a personalized collection of beliefs, including the unspoken rules by which we evaluate ourselves (and by which we may even change our own beliefs). How our belief systems come to be formed is a complex process.
Most of us will inherit a our belief systems from our parents and immediate family very early in life, like from ages 0 to 7. Before we are responsible for our own actions, or even aware of our own decisions and consequences, we are encouraged by our parents to do “good” things and discouraged from doing “bad” things. Our belief systems are formed as a result of our actions and experiences, most of these given to us by grown-ups who punish bad actions and praise good actions, and as a result, our belief system in early life tends to be a reflection of our parents (who we were basically copying for a lot of that time).
About the time we start getting held responsible for our actions and their consequences, we start to evaluate our own beliefs. This process can be thought of as a continuous cycle between actions and experiences. Our current set of beliefs will determine our decisions and actions. Then, our actions will lead to consequences which we feel are either negative or positive. Finally, our beliefs are influenced by the experiences: a positive experience will strengthen our beliefs, while a negative experience will lead us to question or even abandon our beliefs.
During adolescence, we will be moving away from “doing what we’re told” and toward being a “free agent” and acting independently. The cycle is mostly the same, though. In our early years, we copy what others are doing or we do what we are told to do, and that leads to either positive or negative experiences. Later in life, we do what we decide to do, which is mostly the same as what we had been doing the year before, and we have more positive or negative experiences. All of these go toward shaping our belief systems.
Most beliefs of this type are of the proper behavior type, or the should type. They can be habits or manners that have served us well, so we keep doing them, or they can be skills we have learned by trial and error. Another way of looking at these are as cause and effect assertions. These form the basis of our behavior, and they also determine the expectations we have of others.
There is another type of belief which I will call a faith assertion. This is not necessarily a religious or sacred thing; it just means “something we feel strongly is true but can’t verify through observations.” For example, I believe there is an afterlife. The idea of reincarnation makes sense to me, and I choose to believe in it, not only because it is intuitively appealing as an idea, but also because this lets me go through life without fearing death as much as I otherwise would. There is no observation I can make which will prove or disprove my assertion, so while I am able to believe in an afterlife, I will probably continue to do so.
Our fears are part of our beliefs too. Some fears are based on our reasoning and our interpretation of cause and effect, and some are an emotional reaction to a negative experience in our past, and I think most fears are a combination of both thoughts and emotions each to varying degrees.