cogitator--prophetes.ai

cogitator
  (ˈkɒdʒɪteɪtə(r))
  [f. cogitate + -or.]
  One who cogitates, a thinker.

1831 Carlyle Sart. Res. (1858) 31 Cogito, ergo sum. Alas, poor Cogitator, this takes us but a little way.

Oxford English Dictionary