AS101 Lecture Notes - Lecture 4: Soundness, Peanut Butter, Modus Ponens
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Ex. if i win the lottery, then i will retire to the bahamas. A state of affairs that, once true, is enough for something else to be true. If x is sufficient for y, then if x is true, y is true. A state of affairs that must be true in order for something else to be true but is not enough to make something else true. If x is necessary for y, then if x is not true, y is not true. Examples: if john is a bachelor, then john is male. This means john"s being a bachelor is sufficient for john"s being a male. John"s being male is necessary for john"s being a bachelor: if john is a bachelor, then john is unmarried. This means john"s being a bachelor is sufficient for john"s being unmarried. John being unmarried is necessary for john"s being a bachelor. Groups of objects that share a particular characteristic.
