Genius (it's been said) philosophically isn't tweeting? Wrong (12)
I believe the answer is:
wittgenstein
'genius it's been said philosophically' is the definition.
I can't judge whether this defines the answer.
'isn't tweeting? wrong' is the wordplay.
'wrong' is an anagram indicator.
'isnt'+'tweeting'='isnttweeting'
'isnttweeting' is an anagram of 'WITTGENSTEIN'.
Can you help me to learn more?
(Other definitions for wittgenstein that I've seen before include "Ludwig --, Austrian-born philosopher" , "British philosopher" .)