The rationale behind Pierre Duhem's natural classification

• I argue that Duhem doesn’t fit any standard instrumentalist or realist account.
• Duhem was not so concerned with the truth of theory.
• Duhem was rather interested in the pragmatic rationality of the physicist.
• I situate him in Chang’s scheme of activities and principles that rationalize them.
• For Duhem, the ‘principle’ of natural classification rationalizes pursuing theory.

The central concern of this paper is the interpretation of Duhem's attitude towards physical theory. Based on his view that the classification of experimental laws yielded by theory progressively approaches a natural classification—a classification reflecting that of underlying realities—Duhem has been construed as a realist of sorts in recent literature. Here I argue that his positive attitude towards the theoretic classification of laws had rather to do with the pragmatic rationality of the physicist. Duhem's idea of natural classification was an intuitive idea in the mind of the physicist that had to be affirmed in order to justify the physicist's pursuit of theory.