Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
SUPERLATIVE DEGREE USED OF TWO
Although locutions such as the best of the two are unacceptable in most Edited English, American penchant for hyperbole and other forms of enthusiasm gives us many examples, in Semiformal and Informal writing and at all levels of speech except the Oratorical, of the superlative forms of adjectives and adverbs being used where the comparative might be required. Most Standard users would make no demur in relaxed circumstances over Math and physics are both hard for me, but physics is hardest, but many would want harder at the higher levels of speech and in any but the most Informal writing.
