The whatness of pleasure is a topic which demands a thorough and accurate investigation. The study of this topic was also of particular importance in the view of Ibn Sina. A part of this investigation concerns his mode of encounter with the related views of his predecessors. The purpose of this paper is to explore the development of early thinkers’ ideas regarding pleasure and the extent of their impact on Ibn Sina’s views. The findings of this study are two-fold: firstly, in his critical review of the definition provided by Zakariya al-Razi, Ibn Sina presents an accurate explanation of its defects. However, this critique has mostly been attributed to Fakhr al-Din Razi. Secondly, in his later examination of early thinkers’ views of pleasure, he benefits from the Second Teacher’s brief explanation regarding the definition of pleasure. Hence, he owes his insight in this respect to Farabi. Given the various criticisms of Razi’s definition, Ibn Sina overlooks it and, through resorting to Farabi’s ontological approach to the whatness of pleasure, adopts his view as the basis of his own definition. Next, based on his own Peripatetic and perfection-oriented principles, he completes his own definition of pleasure in his works so that the presented definition is later confirmed and accepted as the basis for the related discussions.