rationalist

from WordNet (r) 3.0 (2006)

rationalist
    adj 1: of or relating to or characteristic of rationalism;
           "rationalist philosophy"
    n 1: someone who emphasizes observable facts and excludes
         metaphysical speculation about origins or ultimate causes
         [syn: {positivist}, {rationalist}]

from The Collaborative International Dictionary of English v.0.48

Rationalist \Ra"tion*al*ist\, n. [Cf. F. rationaliste.]
   One who accepts rationalism as a theory or system; also,
   disparagingly, a false reasoner. See Citation under
   {Reasonist}.
   [1913 Webster] Rationalistic

[email protected]