 The principle that undermined Frege’s system, Basic Law V, was one that attempted to systematize the notions ‘course-of-values of a function’ and ‘extension of a concept’. The course-of-values of a function \(f\) is something like a set of ordered pairs that records the value \(f(x)\) for every argument \( x\). For example, the course-of-values of the function father of x records, among other things, that Bill Clinton is the value of the function when Chelsea Clinton is the argument. The course-of-values for the function \(x^2\) records, among other things, that the number 4 is the value when the number 2 is the argument, that 9 is the value when 3 is the argument, etc. When a function \(f\) is a concept, Frege called the course-of-values for that concept its extension. The extension of a concept is something like the set of all objects that fall under the concept, for the extension records all of the objects that the concept maps to The True. For example, the extension of the concept \(x\) is a positive even integer less than 8 is something like the set consisting of the numbers 2, 4, and 6.