PHIL 130g Lecture Notes - Lecture 2: Definition, If And Only If, Continental Philosophy
Document Summary
What is philosophy: on definitions, every definition has two parts: (i) the definiendum the thing being defined, and (ii) the definiens the definition being given. =df should be read as means by definition. ". X is a triangle" is the definiendum, and the other expression is the definiens: definition desiderata, anyone who understands the meaning of the definiendum understands the content of the definiens. Because the meaning of the definiendum is the definiens: in every possible scenario, the definiendum applies to all and only the things to which the definiens applies. Example: x is a triangle" =df x is a two-dimensional closed figure with exactly three straight sides. ". Everything that is a triangle is a two-dimensional closed figure with exactly three sides, and everything that is a two-dimensional closed figure with exactly three sides is a triangle. If you can ever find something for which this is not the case, you have a counterexample, and the definition is wrong.
