PHL 201 Lecture Notes - Lecture 4: Necessity And Sufficiency
Document Summary
Careless or conventional definitions can lead to erroneous argument confusion. Philosophical definitions - a term has been defined if it meets a set of individually necessary conditions that together make a sufficient condition. Dictionary definitions only give what people have defined it to be. Necessary condition: a condition q is necessary for p if it"s not possible for something to be p without being q. Example: being a mammal is necessary for being a dog. Sufficient condition: a guarantee; a condition is sufficient for p if it"s impossible for something to be q and not be p. Example: being a grandfather is sufficient for being a father. You can"t switch p and q around. Being a dog is a __necessary__ condition for being a collie. Being rich is __neither__ a condition for being happy. Being immortal is __neither__ a condition for being a superhero. Being born in nyc is __sufficient__ for being a u. s citizen.
