theorist

plural theorists

1. Someone who constructs theories, especially in the arts or sciences.

   Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains.

   2012 January 28, Michael Riordan, “Tackling Infinity”, in American Scientist, volume 100, number 1, archived from the original on 30 Apr 2013, page 86

   1 more example

   The works of Wilhelm Weitling (1808-71) stand out amid the communist utopias of the 1840s not because he was in any sense a forerunner of Marx, but because he was himself a member of the working class and therefore a better exponent of its attitude at the time than were theorists belonging to the privileged classes.

   1978 [1976], Leszek Kołakowski, translated by P[aul] S[teven] Falla, Main Currents of Marxism, volume I: The Founders, Oxford: Clarendon Press, translation of Główne nurty marksizmu: powstanie (in Polish), →ISBN, →OCLC, page 211

   Synonyms: theoretician, theorizer, theoriser