 Bealer argues that rational intuitions depend on concept possession and if one fully understands a concept, they will be necessarily reliable in ideal cognitive conditions in applying that concept. A person can misunderstand a concept such as arthritis and apply it to pains in the thigh, or incompletely understand it by not knowing whether it applies to a certain case or not. For example, someone might not understand the concept of a contract well enough to know whether it applies to any oral agreements (1998: 221). But full understanding of concepts is incompatible with any misunderstanding or incomplete understanding.