re a visit from the jehovah s witnesses suopanki stekt oulu fi writes on apr mst jbrown batman bmd trw com said god is eternal a b jesus is god c a therefore jesus is eternal c b this works both logically and mathematically god is of the set of things which are eternal jesus is a subset of god therefore jesus belongs to the set of things which are eternal everything isn t always so logical mercedes is a car that girl is mercedes therefore that girl is a car unfortunately your phrasing is ambiguous re writing more carefully we have at least two possibilities the first things called mercedes are cars that girl is called mercedes therefore that girl is a car that is entirely valid as a piece of logical deduction it is not sound because the first statement is false similarly i would hold that jim s example is valid but not sound another possible interpretation of what you wrote is there exists at least one car called mercedes that girl is called mercedes therefore that girl is a car which isn t valid mathew
