PHL101Y1 Lecture Notes - Lecture 1: Tagliatelle, If And Only If
Document Summary
Numerical identity x and y are numerically identical if and only if they are one and the same thing. Qualitative identity x and y are qualitatively identical if and only if they have exactly the same properties. When we ask about personal identity over time, we are asking about numerical identity, not qualitative identity. Leibniz"s law if x is numerically identical to y, then x and y have exactly the same properties. Jim"s favorite dish was chicken and dumplings; 2016-jim"s favorite dish is tagliatelle al rag . So 1996-jim and 2016-jim don"t have exactly the same properties and hence, by leibniz"s law as we"ve stated it, aren"t one and the same person. 1996-jim and 2016-jim are one and the same person. It"s just that this person"s tastes have changed over the years. We will discuss some of the problems and prospects for three answers to our above questions.
