Belief, in simplest terms, is what the mind accepts as true. One can believe something to be true without having knowledge that it is true. Also, one can believe something to varying degrees of certainty (see also Probability).
Degree of belief
Common phrases describing ones own degree of belief:
- I know that
- I believe that
- I think that
- I feel that
- I [would] guess that
- I [would] bet/wager that
- I [would] like to think/believe that
- I have no reason to doubt that
- I have no reason not to believe/think that
Common phrases describing the degree of believability of a statement of fact:
- It is true
- It is certainly true
- It is surely true
- It is almost certainly/surely true
- It is most likely true
- It is likely true
- It is probably true
- It is possibly true
- It is perhaps true
- It may be true
- It might be true
- It should be true
- It can/could be true
In addition, most of the above statements could be negated in two different ways, giving rise to different connotations. For example, "It is not likely [to be] true" is different from "It is likely not [to be] true".
Belief vs. faith
Believing something without evidence (or in the face of contradictory evidence) is often called faith. "Belief" does not always imply "faith," as one can believe something based on evidence or other rational reasons (e.g., logical arguments).
For example, one does not need to have faith that the sun will rise tomorrow, since the fact that the sun rises every day is supported by a lifetime of personal experience, thousands of years worth of recorded observation, and a scientific model of the earth's rotation on its axis.
Belief in something
Having belief in something is different from simply having a belief.
Calling someone a believer usually connotes belief in a god, especially the Christian God (in the U.S., anyway). Sometimes the belief is related to other claims, such as ESP or alien abduction.