For 10 points, name this German logician and author of Foundations of Arithmetic.
This man used the sentences "Vienna is the capital of Austria" and "Trieste is no Vienna" to show the meaning of a word depends on the entire proposition it appears in. An article critical of this man's theories attacked his artificial "null-class" to hold expressions like "the present King of France." He introduced a "turnstile" symbol still used to denote derivability in his Begriffsschrift, and explained why a phrase like "The evening star is the morning star" was not tautological by distinguishing between the sense and reference of a denotation. For 10 points, name this German logician and author of Foundations of Arithmetic.
This man used the sentences "Vienna is the capital of Austria" and "Trieste is no Vienna" to show the meaning of a word depends on the entire proposition it appears in.
Gottlob Frege