Methodological naturalism

The position is procedural rather than metaphysical. A methodological naturalist need not claim that ghosts, gods, or miracles do not exist; they only claim that, when doing science, you proceed as if they do not. The reasoning is practical: if any unexplained phenomenon is allowed to bottom out in "a supernatural agent did it," there is no further investigation to be done, no prediction to make, no follow-up experiment to run. Restricting science to natural causes is what gives it the traction it has.

Methodological naturalism is the consensus working assumption of modern science and is endorsed by major scientific bodies including the National Academy of Sciences and the National Center for Science Education. It is what allows a Christian biologist and an atheist biologist to do the same experiment and reach the same conclusion: both, while at the bench, are looking only for natural mechanisms, regardless of their wider metaphysical views.

Critics from the intelligent-design movement have argued that methodological naturalism rules out evidence for design by definition, making the question of supernatural causation untestable in principle. Defenders respond that nothing prevents anyone from proposing a supernatural-cause hypothesis; the issue is that such hypotheses do not generate testable predictions, and so they fail to do scientific work. The question of whether they could in principle do so is a substantive debate in philosophy of science.

Methodological naturalism should be distinguished from metaphysical naturalism, which is the stronger claim that nature is all there is. Many religious scientists are methodological naturalists at work and theists at home; the procedural commitment does not entail the metaphysical one. The distinction is essential when discussing whether "science presupposes atheism" — it does not, though metaphysical naturalists do treat the explanatory success of methodological naturalism as evidence for the stronger view.