Wiki article on this topic: Related concepts and fundamentals:
Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to assent to any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty, distrust or lack of conviction on certain facts, actions, motives, or decisions. Doubt can result in delaying or rejecting relevant action out of concern for mistakes or missed opportunities.
The concept of doubt as a suspense between two contradictory propositions covers a range of phenomena: on a level of the mind it involves reasoning, examination of facts and evidence and on an emotional level believing and disbelieving
In premodern theology doubt was "the voice of an uncertain conscience" and important to realize, because when in doubt "the safer way is not to act at all".
Doubt sometimes tends to call on reason. Doubt may encourage people to hesitate before acting, and/or to apply more rigorous methods. Doubt may have particular importance as leading towards disbelief or non-acceptance.
Politics, ethics and law, with decisions that often determine the course of individual life, place great importance on doubt, and often foster elaborate adversarial processes to carefully sort through all available evidence.
Societally, doubt creates an atmosphere of distrust, being accusatory in nature and de facto alleging either foolishness or deceit on the part of another. Such a stance has been fostered in Western European society since the Enlightenment, in opposition to tradition and authority.
Sigmund Freud's psychoanalytic theory attributes doubt to childhood, when the ego develops. Childhood experiences, these theories maintain, can plant doubt about one's abilities and even about one's very identity.
Cognitive mental as well as more spiritual approaches abound in response to the wide variety of potential causes for doubt. Behavioral therapy — in which a person systematically asks his own mind if the doubt has any real basis — uses rational, Socratic methods. This method contrasts to those of say, the Buddhist faith, which involve a more esoteric approach to doubt and inaction. Buddhism sees doubt as a negative attachment to one's perceived past and future. To let go of the personal history of one's life plays a central role in releasing the doubts — developed in and attached to — that history.