Observer

(l) One who watches without participating. (2) The source of factual evidence; a person who communicates his sense impression of the external environment. (3) Everything said is said to an observer. (Witz, in Von Foerster, 1974) (4) Observer dependence - the concept that knowledge of reality is dependent upon the perceptions of the observer. (5) Observer inseparability - the concept that observation or measurement affects the state of the object being observed, that is, objective measurement or observation from outside a system is not possible, and the act of observing makes the observer part of the system under study. Therefore, the observer or measuring device should be included in the definition of the system. (Weinberg) (6) A system which, through recursive interactions with its own linguistic states, may always linguistically interact with its own states as if with representations of its interactions. (Maturana and Varela, 1979)