To explain the source of science’s power, we often hear a simple formula saying that science relies on an assumption of "methodological naturalism". But what could "methodological naturalism" mean? I don’t think that science can be equated with methodological naturalism.
Science is all about methodology, but what does the "naturalism" part add? If naturalism just means "current scientific knowledge", then we can substitute that phrase into our formula, and we get:
"Science relies on the methodology for knowing current scientific knowledge."
Well, yes, science is all about methodology, the methods of experimental inquiry. But our formula now just seems circular, trying only to say "science is what science does." We are left with an obvious tautology — not false, but not explanatory either. Also, the "naturalism" part is superfluous and drops out, having no informative role.
Maybe naturalism means "only what is natural really exists". Nice, but what does "natural" mean? If "natural" means "what science knows" then we get:
"Science is the methodology for knowing about what science knows actually exists."
Well, this is not an improvement either. Again, we get an uninformative tautology, amounting to "science studies nature, and nature is what science studies." This tautology lets religions imprison science in a tight cell, incompetent to study anything that seems unnatural to people. Miracles? Science is, by this definition, unable to say anything intelligible about miracles, since miracles are violations of natural laws while science can only study natural laws. The mind? Consciousness is obviously immaterial so science by this definition can’t begin to explain the mind. Our morality? Morality can’t be found out in nature so science by this definition can’t know anything about morality or help with improving morality. And God? By this definition, science must be utterly silent about the supernatural.
This myth that science is limited to "the natural" has been extraordinarily helpful to theological defenses of the supernatural. The Enlightenment age way of accommodating science with religion simply divided up all reality into the natural and the supernatural, letting science study the natural and permitting religion to describe the supernatural. Saying that "science is methodological naturalism" just repeats this dualistic theological formula. Why should we let theology set boundaries to science? How did theology get the authority to declare that some extraordinary events and unusual experiences are off-limits to scientific inquiry? And how did science let theology do this? Why should scientists (such as Stephen Jay Gould ) accept the notion of "Two Magisteria", two separate ways of knowing two different kinds of realities?
Besides, the notion that science is limited to naturalism is just false. Science itself disproves this. Since naturalism bases its worldview on current scientific knowledge, and science’s progress is constantly revising current scientific knowledge, then science’s progress constantly refutes naturalism. Of course, naturalism fast updates itself, so naturalism really isn’t "refuted" by science, as if science could help supernaturalism instead. Rather, science perpetually transcends what is taken to be natural at any moment in time. There is no limitation upon scientific imagination. Sciences occasionally postulate wildly counterintuitive and "unnatural" things that violate both common sense and what counted as natural according to older scientific knowledge. And that is why science will always be a threat to religion, no matter what religion wants to think about science’s limitations. Religion is rightly intimidated by science’s power, since science has a long track record of refuting mythological explanations of the world.
Religion is hardly more imaginative or weirder than science. Religion offers belief in mildly counter-intuitive things like talking animals, flying demons, personalities surviving bodily death, and human-like deities with superpowers. However, science offers belief in maximally counter-intuitive things such as forces that act at a distance, electrons that don’t have any definite location, matter that consists mostly of empty space, empty space that spontaneously erupts in uncaused energy, a universe of unimaginable size, and multiple universes existing in extra dimensions. Ever since the first astronomers discovered how the heavenly lights obeyed strict laws, religions have struggled to keep up with the incredible new visions of the world supplied by science. Indeed, that is the typical function of elaborate theological systems, which go well beyond faith to "intellectualize" religious stories to stay compatible with science, since science constantly refutes mythologies. That’s why we now see, for example, religious people giddy with excitement over quantum phenomena . Fundamentalisms are the rare "frozen theologies" which instead conservatively fight science in an all-or-nothing manner. Most theologies eventually offer accommodations to science (even though science cannot return the favor).
There is another tautology telling science where it can’t go — "science can’t investigate the supernatural to disprove God". If supernatural means "utterly beyond the reach of empirical inquiry and human conception" then this tautology is valid. However, it really doesn’t limit science, but only limits theology. If theology really wants to be in the business of telling people to keep the faith in an utterly mysterious divinity, common sense rationality is enough for skeptically eroding that theology. Science doesn’t even have to worry itself with confronting theology on such vaporous ground — just let a little logic and philosophy handle such thin theology.
Science’s methodology of testing imagination through experimental inquiry is so powerful that it always pushes beyond whatever is taken to be ordinary and natural. Scientific progress depends on investigating and theorizing about surprisingly unnatural things that disrupt the old worldview of nature. There is no arbitrary limit to the range of human experience and conceivable reality open for scientific investigation.
That’s why naturalism must constantly be updated, to keep all scientific knowledge coordinated and comprehensive, and this work is philosophical work. Philosophical naturalism undertakes the responsibility for elaborating a comprehensive and coherent worldview based on experience, reason, and science, and for defending science’s exclusive right to explore and theorize about all of reality, without any interference from tradition, superstition, mysticism, religious dogmatism, or priestly authority. Naturalism, and not any particular science, is the right tool for confronting abstract theological arguments over the existence of God.
Science simply can’t be delimited or defined by what science tries to investigate or what science can postulate. The essence of science is its powerful methodology, the ways that the sciences logically test their hypotheses against fresh evidence. The Enlightenment wall of separation has already fallen, brought down by science itself. Now we just need more scientists and philosophers (and of course everyone else) to notice.