Intersubjective verifiability is the capacity of a concept to be readily and accurately communicated between different individuals ("intersubjectively"), and to be reproduced under varying circumstances for the purposes of verification. It is a core principle of empirical, scientific investigation. Although there are areas of belief that do not consistently employ intersubjective verifiability (e.g., many religious claims), intersubjective verifiability is a near-universal way of arbitrating truth claims used by people everywhere. In its basic form, it can be found in colloquial expressions, e.g., "I'm from Missouri. Show me!" or "Seeing is believing". The scientific principle of replication of findings by investigators other than those that first reported the phenomenon is simply a more highly structured form of the universal principle of intersubjective verifiability. Subjective experience Each individual is a subject, and must subjectively experience the physical world. Each subject has a different perspective and point of view on various aspects of the world. However, by sharing their comparable experiences intersubjectively, individuals may gain an increasingly similar understanding of the world. In this way, many different subjective experiences can come together to form intersubjective ones that are less likely to be prone to individual bias or gaps in knowledge. While specific internal experiences are not intersubjectively verifiable, the existence of thematic patterns of internal experience can be intersubjectively verified. For example, whether or not people are telling what they believe to be the truth when they make claims can only be known by the claimants. However, we can intersubjectively verify that people almost universally experience discomfort (hunger) when they haven't had enough to eat. We generally have only a crude ability to compare (measure) internal experiences. Congruence and incongruence When an external, public phenomenon is experienced and carefully described (in words or measurements) by one individual, other individuals can see if their experiences of the phenomenon "fit" the description. If they do, a sense of congruence between one subject and another occurs. This is the basis for a definition of what is true that is agreed upon by the involved parties. If the description does not fit the experience of one or more of the parties involved, incongruence occurs instead. Incongruent contradictions between the experience and descriptions of different individuals can be caused by a number of factors. One common source of incongruence is the inconsistent use of language in the descriptions people use, such as the same words being used differently.