"When I use a word," Humpty Dumpty said, in rather a scornful tone, "it means just what I choose it to mean—neither more nor less." Through the Looking-Glass—Lewis Carroll1
LEWIS CARROLL taught and wrote books on both logic and mathematics. He was aware of the enormous confusion that can result from the unintended meanings of words.1 In Carroll's time, there was a lively debate concerning the existential importof statements such as All A is B. In medicine, this statement is known as the pathognomonic premise. Today, there is a lively debate concerning an instance of this premise in which A is erythema migrans and B is Lyme disease.2-6