Why did John Searle reject both Cartesian dualism and the reduction of mental states to physical descriptions?

John Searle rejects both Cartesian dualism and the reduction of mental states to physical descriptions because he views them as based on an outmoded and misconceived dichotomy between mind and matter.12

Searle argues that the mind-body problem is fundamentally flawed because it assumes minds and bodies are radically different substances, a view famously maintained by René Descartes. Instead, Searle posits that mental states are intrinsic, biological features of complex systems.1

He rejects the reduction of mental states to physical descriptions because he believes that mental phenomena cannot be eliminated in favor of a strictly physical vocabulary; reference to mental states remains essential for explaining human behavior. By characterizing consciousness as a biological phenomenon—comparable to digestion—Searle avoids the "ghost in the machine" trap of dualism while maintaining that mental states are real, irreducible features of the biological world.12