Some critics object to materialism as part of an overly skeptical, narrow or reductivist approach to theorizing, rather than to the ontological claim that matter is the only substance. Particle physicist and Anglican theologian John Polkinghorne objects to what he calls promissory materialism — claims that materialistic science will eventually succeed in explaining phenomena it has not so far been able to explain. Polkinghorne prefers "dual-aspect monism" to faith in materialism.

Instead of faith, John Polkinghorne relies on what when it comes to the theory of materialism?