Jacques the Fatalist and His Master by Denis Diderot exhibits a philosophical style of prose and explores various themes. The most prominent theme is the in-depth analysis of morality—in particular, the moral responsibility of individuals. The novel also touches on the theme of determinism, which is a philosophical concept stating that every decision one makes and every action taken is determined by prior occurrences.

The theme of determinism is juxtaposed with the idea of fate—the consequence of random events believed to be predetermined—as both Jacques's and his master's lives are in the hands of fate. The novel illustrates that events that occur in life are mostly out of our control.

The theme of progression, or a form of journey, is also present in the novel. The physical, geographical journey the duo takes runs parallel with inner journeys told through their respective stories. They are both physically traveling outward, but the more stories they tell, the further they go inward in a journey of self-reflection and self-discovery. Both the actual and internal journeys are needed to help the two men complete a spiritual metamorphosis.