This thinker argued that, as Plato’s own beliefs changed, the persona of his character Socrates changed, a view which has been dubbed the “mouthpiece theory.” For 10 points each: 
[10h] Name this philosopher whose 1992 book Socrates: Ironist and Moral Philosopher argues that Socratic philosophy should be studied as something distinct from Platonism. 
ANSWER: Gregory Vlastos 
[10m] Vlastos grouped many of Plato’s early dialogues like the Apology and Crito together because they use this method of argumentation, colloquially called the “Socratic method,” which consists of a series of questions and answers.
ANSWER: method of elenchus [or elenctic method or elenchi] 
[10e] In a 1954 article, Vlastos analyzes the third man argument, which appears in this Platonic dialogue named for a philosopher from the Eleatic School.
ANSWER: Parmenides
<Caleb Kendrick, Philosophy>