The word ‘variable’ in logic,mathematics and economics

The paper deals with the meaning of the word variable as used by various authors in various disciplines. In the first part of his article the author explains the synonyms used for this word such as indefinite numbers, mappings or concepts. He further discusses the meaning of variables and unknowns as applied in modern logic and traditional mathematics. In economic models the variable is inseparably linked to the economic quantity by which it is characterized and interpreted. Distinctions are made between endogenous and exogenous variables and between a variable and its time path.The author is indebted to Tor Fernholm for valuable comments on a preliminary draft.