This paper aims to examine the most important aspects of Enlightenment philosophy (and its main authors: Locke, Condillac, Diderot, Beccaria, Montesquieu) with special reference to the following topics: 1. The analysis of cognitive faculties and denial of the existence of innate ideas; 2. The criticisms of the concept of absolute authority; 3. The sovereignty and freedom of the individual; 4. Cartesian dualism between soul and body, between thought and matter. 5. The rejection of anthropocentrism led to criticism of providentialism; 6. The relationship between man and animals, and the discussions about the matter of animal language. This new formulation of ideas from the century of Enlightenment is of fundamental importance, and although not all of the hoped-for objectives were achieved – for example, those concerning human rights - their ideal was widely accepted, and those who criticise the existing order today do so in the name of Enlightenment.