SUMMARY. — In the period in which Georges Canguilhem published his chief works, Anglo-American philosophy of science was dominated by logical positivism or logical empiricism. After a comparison of the differing styles of the two enterprises, several logical empiricist theses are contrasted with the corresponding view of Canguilhem : 1. philosophy of science as non-historical or weakly historical ; 2. the separation of « justification » from « discovery » ; 3. the unity of science ; 4. physics as the primary model for philosophy of science ; 5. reductionism ; 6. the role of theory and observation.