Why did Hippolyte Taine criticize Victor Cousin’s eclectic philosophy?

Hippolyte Taine’s criticism of Victor Cousin’s eclectic philosophy was rooted in Taine’s commitment to positivism and his desire to apply the scientific method to the study of the humanities.1

Taine, who believed that all knowledge must be based on sense experience, observation, and controlled experiment, found the prevailing eclectic doctrine championed by Cousin and his followers to be fundamentally at odds with his own rationalist and scientific outlook. His opposition was most notably expressed in his 1857 work, Les Philosophes français du XIXe siècle ("The French Philosophers of the 19th Century"), which served as a critical polemic against Cousin’s system.1

Specifically, Taine opposed the speculative and introspective approach inherent in the eclectics' methodology. While Cousin’s eclecticism involved assembling a system by borrowing elements from various other philosophies to serve his purposes, Taine sought a total explanation of the causal forces of life and the universe through empirical study. Taine’s later work, De l’intelligence ("On Intelligence"), further solidified this divide by advocating for a scientific methodology that emphasized experimentation and the physiological basis of personality, directly challenging the eclectics' reliance on introspection.12