1) Expert 2) French word used in English 3) Logistician 4) Pro at sound reasoning 5) Spock, notably 6) Straight thinker 7) Syllogist Found on https://www.crosswordclues.com/clue/logician
any member of a school of Chinese philosophers of the Warring States period (475–221 Bc). In Chinese the school is called Ming-chia (Pinyin Mingjia), ... [1 related articles] Found on http://www.britannica.com/eb/a-z/l/67
Lo·gi'cian noun [ Confer French logicien .] A person skilled in logic. Bacon. « Each fierce logician still expelling Locke.» Pope. Found on http://www.encyclo.co.uk/webster/L/57