the·o·rist /ˈθiərɪst, ˈθɪ(ə)rɪst/
  理論家,空談家
  The·o·rist n.  One who forms theories; one given to theory and speculation; a speculatist.
     The greatest theoretists have given the preference to such a government as that which obtains in this kingdom.   --Addison.
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  theorist
       n : someone who theorizes (especially in science or art) [syn: theoretician,
            theorizer, theoriser]