By dealing with Hannah Arendt's view on thinking, this paper aims to reveal the arguments on which Arendt has established the relationship between thinking and evil. The article, which is divided into two main sections, first examines the nature of thinking that Arendt refrains from defining. The difference between thinking and knowing, along with the question of why thinking is an activity; thus its distinction from contemplation in the traditional philosophy, constitute the main problems of this section. The second part of the article is on thinking as an internal, silent dialogue which according to Arendt is the only positive definition that can be made about it. For her, this way of thinking exemplified by Socrates and based on the duality that one has on his own, is important for reducing the possibility of one's evildoing, even though it cannot prevent it completely. The study concludes by examining the reflections of thinking in action.