The Bostonians and The Princess Casamassima, out of the complete novels of Henry James, are assorted as social novels which directly deal with the social issues of the time. In the writing of the latter, James arranges the concrete description of the social environment of London in the late 19th century along with the impressionistic description of the psychological condition of Hyacinth Robinson, the hero of the novel. Thus it effectively shows how some contemporary social ideas have been projected in the consciousness of the protagonist. This paper interprets the characteristics of the experience of Hyacinth in the light of the contrasting epistemological viewpoints of rationalism and empiricism. Hyacinth undergoes a biting inner conflict and confusion while he struggles to achieve his self-definition and self-accomplishment in the fluid social atmosphere of London in 1880’s. James, as writer of psychological realism, tends to focus the narration of most of his novels on how such elements of perception as impressions, ideas, thoughts and feeling, experience and personality are functioning in human consciousness. He explores the epistemological aspect in which the two contradictory tendencies, that is, the rationalistic and the empirical, interplay in our mind. In The Princess Casamassima, the opposing perceptive traits, such as reason and ideas versus thoughts and feeling, cause severe inner contradictions in the hero’s mind, which finally lead to his tragic self-destruction.