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L ogic, philosophy of mathematics In ordinary language, a function roughly means a purpose or role. In logic and mathematics, a function is a particular kind of relation in which given any object or objects (called an argument of the function), another object (called the value of the function for that argument) will be yielded. A function has one or more variables , which can take different arguments. Giving definite values to the variables of a function yields a definite value to the whole function. Truth-functions in propositional logic (also called functional calculus) are special functions in which the truth-value of a compound proposition is determined by the truth-values of its propositional components and by the logical terms connecting them. A function is applicable to a certain class of objects. The class to which the function applies is called the domain of the function, and the class of values is called the range of the function. Frege held that concepts are functions that map objects onto truth-values . “A function is, as observed, a relation. But it is a relation of a special sort, having the peculiarity that no two elements bear it to the same element.” Quine, Mathematical Logic ... log in or subscribe to read full text