I came across Etymonline's explanation for the word sophomore. I do not understand why this has come to be applied to second-years. Why is a second-year guy a wise one and a fool?
"Student in the second year of university study," literally "arguer," altered from sophumer (1650s, from sophume, archaic variant form of sophism), probably by influence of folk etymology derivation from Greek sophos "wise" + mōros "foolish, dull" (see moron). The original reference might be to the dialectic exercises that formed a large part of education in the middle years. At Oxford and Cambridge, a sophister (from sophist with spurious -er as in philosopher) was a second- or third-year student (what Americans would call a "junior" might be a senior sophister).