Charles-Louis de Secondat , Baron de La BrÃ de et de Montesquieu ( January 18 , 1689 â `` February 10 , 1755 ) , more commonly known as Montesquieu , was a French political thinker . Charles-Louis de Secondat , baron de La BrÃ de et de Montesquieu ( Ë mÉ n tÉ skjuË , ; 18 January 1689 â `` 10 February 1755 ) , generally referred to as simply Montesquieu , was a French social commentator and political thinker who lived during the Enlightenment .