Arbitrarily Selected Individuals in Natural Deduction
Vito F. Sinisi · Analysis · 1963
IN Arbitrary Individuals and Natural Deduction 1 Robert Price argues that natural deduction may avoid the difficulties caused the introduction of arbitrarily selected individual by the simple expedient of dispensing with arbitrary individuals altogether. He gives an interpretation of the rules of natural deduction which involves only bound terms (variables, place-markers, or what you will) and free terms (names of individuals); x, y, z, ... will be used for the former and a, b, c, ... for the latter. Furthermore, In the statement of Universal Generalization (UG) it will be understood that Ox is like Oa except for containing occurrences of free x wherever ba contains occurrences of a. The rule of UG is stated as follows: