Philosophical & Methodological Naturalism

This page, containing excerpts from other pages, is an overview. The main themes are: A) methodological naturalism is theologically acceptable for a Christian, but... B) in a scientific search for truth about nature, it doesn't seem wise to demand that history must be all-natural; C) scientific methodology can influence personal and societal worldviews.

For a condensed overview of the main ideas in this page, read Sections 7C and 7D in my FAQ for Creation, Evolution, and Intelligent Design.

A. Naturalism and Theology

Is methodological naturalism theologically acceptable?
Currently, most scientists adopt methodological naturalism in science by including only natural causes in their scientific theories. But according to the Bible, history has included both natural and non-natural events. Is a naturalistic science compatible with Christianity? I think the answer is "yes" because Christians — who believe that non-natural miracles occur, and who therefore should view a naturalistic science as only one aspect of a broader "search for truth" that considers all possibilities, including the non-natural — can accept methodological naturalism while rejecting extensions beyond science.
According to a nontheistic (atheistic, pantheistic,...) religious philosophy of naturism, nature is all that exists, with no God and no divine action, so everything that happens is caused by matter/energy in natural operation. This philosophical naturism differs from methodological naturalism in two ways. First, methodological is not philosophical; a theist can adopt a methodology (for the purpose of doing science) without accepting it as a philosophy (about the way the world really is) that is used as a basis for living. Second, naturalism is not naturism, as explained below.
terminology: philosophical naturism is usually called philosophical naturalism but also metaphysical naturalism and (because it is a theory about reality) ontological naturalism and also materialism or physicalism. { Multiple terms are used interchangeably or with distinctions that vary. Basically, it's a linguistic mess, very confusing. }

Naturalism is not Naturism
When precise thinking and communication are important, precise definitions are important. To avoid the imprecision (and sloppy thinking) that occurs if the same term is used for different views, I'm using naturalism for only one view, for a claim that "it all happened by natural process" during a stage of history. But most people use "naturalism" to mean both this limited view (claiming "only natural process") and a comprehensive view (claiming "only nature exists"), and one word with two meanings — limited naturalism and comprehensive NATURALISM — can cause confusion.
If we want to avoid confusion, we should avoid using "naturalism" with two meanings. Yes, there can be connections (in some ways but not others) between the two meanings. But when we're thinking about these connections, the clarity of our thinking will improve if we use two terms. Otherwise, it's too easy to fall into sloppy thinking by comparing two ideas called "naturalism" — claiming "only natural process" (usually theologically acceptable) and "only nature exists" (never theologically acceptable) — and concluding that since both have the same name, they're the same in all ways. { This problem is examined more thoroughly in a page about naturalism and NATURALISM. }
To show two differences between naturalism and naturism, the table below shows answers to five questions — Was the universe designed and created by God? Is natural process sustained by God? Is natural process guided by God? Did miracles occur in the formative history of nature? Do miracles occur in the salvation history of humans? — by four theories about origins: Theistic miraculous-appearing creation (Tmac) as in old-earth progressive creation or young-earth creation; Theistic natural-appearing creation (Tnac) as in evolutionary creation, which is also called theistic evolution; deism (D); philosophical Naturism (pN) as in atheism or pantheism.

	Tmac oeC yeC	Tnac EC (TE)	D	pN ath panth
universe designed/created by God?	yes	yes	yes	NO
natural process sustained by God?	yes	yes	?	NO
natural process guided by God?	yes?	yes?	NO	NO
miracles in salvation history?	yes	yes	NO	NO
miracles in formative history?	yes	NO	NO	NO

1) Notice that theistic evolution (with a naturalistic formative history) and deism (with a naturalistic total history, both formative and salvation) both say "yes, the universe was designed and created by God" so despite their historical naturalism (partial or total) they reject the broader claim of naturism that "only nature exists."
2) Beliefs about natural process also differ. Proponents of theistic evolution believe that natural process is designed, created, and sustained by God, and might be guided by God (thus the "yes?" *) so their naturalistic claim that during formative history "it all happened naturally" does not mean "it all happened without God," which is the claim of naturism. A deist believes that natural process is designed, created, and perhaps sustained by God, but is not guided by God. An atheist thinks that only nature exists, so there is no God, and all answers are NO.
* Theists believe that God can guide natural process, but difficult theological questions — about the frequency of such guidance (does God do it always, usually, seldom, or never) and the degree of control (is it partial or total, for situations, thoughts, and/or actions) and whether it differs in stages of history (formative and salvation) — are examined in Theistic Action but not here.

Two Options for Christians
A devout Christian who believes "miracles occurred in salvation history" could evaluate the scientific evidence and conclude that "formative history was all-natural." But should this naturalistic conclusion be the only possibility that is considered during scientific evaluation, as required by methodological naturalism?
In my opinion, there are two rational, theologically acceptable ways for Christians to view methodological naturalism (MN). Among scientists (and other scholars) who are Christians, some support one approach and some think the other is better.

• In one approach, proponents of an open search accept MN but consider MN-science to be only one aspect of a broader "open search for truth" that considers all possibilities, including miracles. Their scientific search, but not their open search, is restricted by MN. Although MN-science is respected as an expert witness, it is not allowed to be the judge and jury when we're defining rationality and searching for truth. { Everyone who accepts MN should also adopt MN-Humility by recognizing the possibility of unavoidable error in MN-Science because if an event really did involve a non-natural cause, any explanation of this event by MN-Science (in terms of only natural causes) will be incomplete or incorrect. }
• In another approach, proponents of open science claim that — since we believe that miracles did occur in salvation history and might have occurred in formative history — we should not assume that "miracles did not occur" while doing science. They propose replacing rigid-MN with a testable-MN in which scientific investigations begin by assuming "it happened by natural process" but consider this to be an assumption, a theory to be tested rather than a conclusion that must be accepted.
In both approaches, a Christian believes that natural process was designed by God, is sustained by God, and can be guided by God, so "natural" does not mean "without God", and a naturalistic explanation does not lead to a conclusion of atheistic naturism.

This section was originally in a page about Theistic Evolution & Theology.

Yes, but... (we should ask some questions)
Although accepting MN can be rational and theologically acceptable for a Christian, we should ask: "What is the most effective way to search for truth about nature, rigid-MN or testable-MN?"
What are the interactions between methodology and philosophy? In a "broader search for truth" about the history of nature, will people seriously consider "nonscientific" theories in a competition with "scientific" theories that (due to MN) must conclude "history was all-natural"?
These questions, and others, are examined in Sections B1, B2, and C.

B1. Closed Science and Open Science

Methodological Naturalism and Closed Science
Currently, most scientific inquiry is closed by methodological naturalism (MN), a proposal to restrict the freedom of scientists by requiring that they include only natural causes in their scientific theories. In a closed science (restricted by MN), evidence and logic are not the determining factors because the inevitable conclusion — no matter what is being studied, or what is the evidence — must be that "it happened by natural process."

Can we avoid the possibility of unavoidable error?
Is MN the best way to do science? Maybe not. It depends on what actually happened in history. We should ask, "Does the assumption match the reality?" because a rigidly enforced MN will probably be scientifically useful IF there is a match between "what MN assumes about the world" and "how the world really is."
Imagine two possible worlds: one has a history of nature with all events caused by natural process, while the other has a history that includes both natural and non-natural events. When we ask, "Which type of world do we live in?", we hope our science will help us, not hinder us, in our search for truth. But in one of the two possible worlds, a closed science (restricted by MN) must inevitably reach the wrong conclusion. By contrast, in either world a non-MN science will allow, although it cannot guarantee, reaching a correct conclusion.

The Freedom of Open Science
Imagine that we're beginning our search for truth with a logically justifiable attitude of humility, by refusing to decide that we already know — with certainty, beyond any doubt — what kind of world we live in. If we don't know whether history has been all-natural, our best scientific strategy for finding truth is an open science, with scientists humbly asking a question instead of arrogantly assuming an answer.
In open science a scientist begins with MN by assuming, consistent with MN, that "it happened by natural process." But an open-thinking scientist is free to use both MN and non-MN modes of thinking while logically evaluating the evidence, to flexibly consider a wider range of possibilities. A scientist begins with an MN-assumption, but does not insist that — no matter what the evidence indicates — it is necessary to end with an MN-conclusion. An open scientist adopts testable-MN instead of rigid-MN, because the assumption of MN is treated as an assumption, as a theory to be tested rather than a conclusion to be accepted as a required dogmatic belief. There is flexible open-minded inquiry, with freedom of thought for the individual and community, and scientists are free to follow the evidence-and-logic wherever it leads. Each theory is evaluated based on its merit, and if a non-MN conclusion is justified by the evidence, this is allowed. {two dogmas}

As explained above & below,
Open Science is Better Science
in a search for truth about nature.

Should science be logical?
If we want science to be a search for truth, should we define science as a search for NATURAL explanations, or a search for LOGICAL explanations? Of course, when we ask "Should science be logical?", everyone agrees that YES is the answer. But disagreements occur when we ask "If there is a conflict between logical and natural, which criterion should have higher priority?" If we want to be logically rational, should we let methodological naturalism force us to accept a "scientific" conclusion that is less logical — and less likely to be true? — simply because it is natural? For example,...

Is evidence irrelevant?
To see the irrelevance of evidence when MN determines the conclusion, compare the evidence-based implausibility (earned by current theories for a "chemical evolution" origin of life) with the naturalism-based confidence of the National Academy of Sciences in claiming that "the question is no longer whether life could have originated by chemical processes. ... the question instead has become which of many pathways might have been followed to produce the first cells." Yes, with MN the evidence is irrelevant. Even though each of the "many pathways" is implausible, one pathway must have produced life — because according to MN this is the only possibility — so confidence does not require evidence. { Words are carefully chosen to avoid technical falsity, by saying "life could have originated" (a statement that cannot be proved false by rigorous logic) and "might have been followed." But the words are also chosen to clearly express the claim that "the question is no longer" whether it did occur naturally, the only question is how it occurred naturally. }
Of course, the irrelevance of evidence does not mean there is no evidence, or that MN is leading to the wrong conclusion. But it does illustrate a logical weakness of MN, since MN requires that we must reach a scientific conclusion before doing any science.

Bypass the Process, Claim the Support
The Conclusion of MN-Science — that no matter what is being studied, or what is the evidence, it happened by natural process — is actually The Assumption of MN. The circular logic of MN, which converts a naturalistic assumption into a naturalistic conclusion, is illogical (because circular logic is bad logic) yet is unavoidable, and it requires no science. But instead of acknowledging this logical weakness of MN-Science, usually MN-Humility is ignored and there is an implication that the assumption made by MN (that it happened by natural process) is a conclusion reached by science, and is therefore true. MN provides a way to bypass the process of science and then claim the authority of science as support.
For example, there is an implication that the declaration by the National Academy of Sciences (speaking with authority in the name of "science") is based on scientific evidence and logic. But the main reason for believing that life had a natural origin is not science. Instead, it is a naturalistic assumption that everything had a natural origin.

Is a closed science theologically acceptable?
For a Christian who believes that God can do miracles, as claimed in the Bible, is a closed science — with MN forcing scientists to assume that no miracles have occurred in the entire history of nature — theologically acceptable? This question is examined in Section A.

Section B in this page (above in B1, and below in B2) contains excerpts from sections that originally were in The Origin of Life. Section B2 begins by observing that "design is common," continues with five questions — Does design violate MN? Is MN scientific? Is MN required by The Rules? Is MN scientifically productive? When is critical thinking unscientific? — and concludes with ideas from a page about Critical Thinking in Closed Science, in a scientific community that says "No, we should not ask the question."

B2. Naturalism and Design

Design is Common in Science
In science, theories of design are common. In every design investigation, scientists ask the same question: If we assume a uniformity of natural process, was undirected natural process sufficient to produce what we observe? Sometimes the answer is "probably not," and design-action is proposed to explain a wide variety of features such as bird nests, ant hills, predator-prey events, paintings on a cave wall, metal satellites in orbit, and faces on Mount Rushmore. A design theory is proposed — for example, when a crime detective concludes that "this death occurred by murder, not natural causes" — when an inference that "design-directed action did occur" can be justified based on a logical evaluation of evidence.
Design is common in science, and most design theories are judged on their scientific merit. But some are controversial, partly due to concerns about naturalism.

Does design violate rigid-MN?
Methodological questions about design occur when design-action seems unfamiliar. In some situations the action and agent are familiar (as when a beaver builds a dam, or humans make faces on Mount Rushmore) but in other cases the design-action is unfamiliar and it could be either natural (for example, if space aliens produced designed features by using their unfamiliar advanced technologies) or supernatural (as in Biblical miracles). Most opponents of design have methodological concerns only when design-action is unfamiliar and it could be supernatural, so the concerns seem religious (not methodological) and a common claim is that a design theory is a creation theory. Is this claim justified?
For any question about design in any area (radioastronomy, homicide, origins,...) we can view the scientific inquiry as a two-stage process: first we ask "Was there design-directed action?", and then we investigate the details. A basic design theory claims only that design-directed action did occur (the first stage) but does not try to explain the details (who, why, how,...) of design-and-production. Of course, we should evaluate a design theory based on what it does claim (that design occurred) instead of what it does not claim (that it can explain the details).
In origins, a design theory is not a creation theory. A basic design theory can be supplemented with details (about the designer's identity and actions, about who, why, how,...) to form a variety of theories about supernatural creation (by God or...) or natural non-creation (as in a theory proposing that evolution on earth was intelligently designed and directed by space aliens who evolved before us). But a basic design theory does not try to distinguish between creation and non-creation, it just claims that "design-directed action did occur." A design theory does not propose divine action, but does acknowledge this as a possibility, so it is potentially non-naturalistic and it violates a rigid-MN.

Is rigid-MN scientific?
A principle of MN cannot be derived from science (so it is nonscientific) but is compatible with science (so it is not unscientific). A more important question is whether rigid-MN is useful in science, whether it makes science more effective in our search for truth about nature. ...
Some scholars think that because a rigid-MN is nonscientific, it should not be required in science. But others think a rigid-MN is useful because, even though it is not based on scientific logic, it makes scientific logic more effective. But if the history of nature has included some non-natural events, rigid-MN will lead to some unavoidable falsity. Therefore, I think science will be more effective in a search for truth with testable-MN that lets scientists use scientific logic to consider all possibilities and decide which is the best explanation for the evidence.

Is rigid-MN required by The Rules?
A design theory acknowledges the possibility of divine action, so it violates a rigid methodological naturalism and thus, according to some people, it violates "the rules of science."
Is science a game with rules? This is an interesting perspective. In terms of sociology, regarding interpersonal dynamics and institutional structures, it is an idea with merit. But it seems less impressive and less appealing when we think about functional logic and the cognitive goals of science. It seems more logical to view science as an activity with goals (which include searching for truth) rather than a game with rules (which include the restrictions imposed by rigid-MN).
Let's compare "cheating" in sports, business, and science. In a Strong Man Contest, if other contestants carry a refrigerator on their backs, one man should not be allowed to move it using a two-wheel cart because this is not useful for achieving the goal of the game, for determining who is the strongest man. But if the goal of a business is to move refrigerators quickly, many times during the day, a two-wheeler is useful.
Although it isn't the only goal, for most scientists the main goal of science is finding truth about nature. But a rigid-MN might lead to unavoidable false conclusions. When some scientists recognize this and decide to reject rigid-MN, is it cheating or wisdom? Is adopting a rigid-MN, rather than a testable-MN, always useful in our search for truth? { Among scholars who carefully study MN, most agree that we should ask "Is it scientifically useful?" instead of relying on dogmatic rules. }

a word-game: In natural science, should natural phenomena and natural history be explained by natural causes? Or is this a circular argument camouflaged by verbal ambiguity?

Will design theories be productive in helping us achieve the goals of science? This is the most important question, according to a consensus of scholars who have carefully examined the issues.

Is rigid-MN scientifically productive?
Perhaps the search by Closed Science (restricted by a rigid methodological naturalism) is occasionally futile, like trying to explain how the faces on Mt Rushmore were produced by undirected natural processes such as erosion. If scientists are restricted by an assumption that is wrong (that does not correspond with historical reality) the finest creativity and logic will fail to find the true origin of the faces.
Occasionally, perhaps MN is forcing scientists into a futile search, like a man who is diligently looking for missing keys in the kitchen when the keys are sitting on a table on the front porch. No matter how hard he searches the kitchen, he won't find the keys because they aren't there! ...<snip>...
Is a claim for design a science-stopper? No, this simplistic "slippery slope" argument is based on narrow either-or thinking, and is unrealistic because most scientists will continue their non-design research — probably with renewed vigor because they are responding to a challenge — when they hear a claim that "maybe a non-design explanation doesn't exist." And proponents of design want non-design research to continue so we can learn more, so we can more accurately evaluate the merits of non-design and design, because the goal is to find truth. They want to supplement non-design research, not replace it. They want to stimulate productive action and critical thinking, with invigorating debates between critics of a theory and its loyal defenders. And this type of scientific stimulation did occur due to Michael Behe's claims for "irreducible complexity" in 1996, although (as explained in Section 3) the current scientific community does not want to acknowledge this scientific stimulation.

When is critical thinking unscientific?
To explain the origin of life, scientists have proposed many theories about chemical evolution, but — since what is required for life seems much greater than what is possible by natural process — each theory seems highly implausible. Supporters of each naturalistic theory point out the weakness in other theories, and their critical thinking is welcomed by the scientific community.
What would make their critical thinking unscientific? a claim that a natural formation of life is extremely improbable, and maybe impossible? a perception (by others) that this claim implies a non-natural cause? an explicit proposal for a non-natural cause? Is there any limit to the severity of criticism before it becomes unscientific? If all non-design theories are criticized and there is a proposal for design-directed action, is this unscientific? If severe criticism is accompanied by a proposal for a naturalistic theory, does this make it scientific?
Can scientists admit that "we are far from finding the answer" but not that "maybe there is no natural answer"? Consistent with the restrictions of Closed Science, should we control the thinking of scientists by removing their freedom to think that "maybe..."? YES, it is unscientific to think "maybe" so this cannot be allowed, claim some scientists, as you'll see in the section below.

From the "closed" side of a page about Critical Thinking in Closed Science and Open Science,

Critical Thinking in Closed Science
Have the benefits of open science earned it a gracious welcome from the scientific community? What has been the response to theories of design? When Michael Behe submitted papers to science journals about irreducible complexity (that he claims could not be produced in a step-by-step process of neo-Darwinian natural evolution) some individual editors were interested, but editorial groups were intolerant. One editorial board concluded its rejection letter, "Our journal... believes that evolutionary explanations of all structures and phenomena of life are possible and inevitable." {from Behe's Correspondence with Science Journals}
In an open-minded free science, the response would be different. Behe's thought-provoking questions would be welcomed as a constructive challenge, an opportunity to gain a more complete understanding of evolution at the molecular level. The journals would be eager to communicate new ideas, to host invigorating debates between critics of a theory and its loyal defenders.
Instead, critical questions are resented and rejected. This response does offer a practical benefit. It lets a community defend the reigning paradigm by using its power to make important decisions: which views will (and won't) be expressed in journals and textbooks, at conferences and in the media? what types of research, by which scientists, will be funded? who will be hired and promoted? and who will determine the policies of scientific and educational organizations?
But a "closed science" does not seem consistent with the lofty ideals of scientists, with their noble vision of science as an intellectually free, objective pursuit of truth. Instead, in a community of scientists who are exploring freely, thinking flexibly, and dedicated to finding truth, Behe's tough questions would be used as a stimulus for critical analysis, creative thinking, and productive action. {details about Behe's Adventures with Journals and several possible Explanations for Rejections}

Should we ask the question?
In the near future, scientists will disagree about the plausibility and utility of design, but conflicts are common in science, and can be productive. Should journal editors wait until proponents of design have irrefutable proof? (*) Proof is impossible in science, and it can be difficult to confidently answer the question, "Was design-action involved in producing this feature?" But it should be much easier to decide, "Should we ask the question?" A curious, open-minded community will say "YES, we want our science to be flexible and open to inquiry, not rigid and closed by dogmatism."

* Two common questions — Can we prove or disprove a design theory? What about future developments in science? — are examined in the "Origin of Life" page and (in condensed form) in a page asking Can a theory of intelligent design be authentically scientific?

Should you examine it more carefully?
Although arguments for excluding design from science make good cartoons and one-line slogans, the arguments seem less logical when you look more closely. Can design be scientific? If you want to explore this question in more depth, another page describes the arguments, analyzes them logically, and concludes that "the closer we examine Open Science, the better it looks."

C. Scientific Methodology and Worldviews

One side of a page about Interactions between Science and Worldviews asks, "Can worldviews influence science?",

Recognize and Minimize
Scientists are influenced by cultural-personal factors that include personal desires, group pressures, philosophical or religious views, and cultural thinking habits. In my opinion, we should recognize the influence of cultural-personal factors, and — in an effort to make science more effective in a search for truth — we should try to minimize the biasing influence of these factors. We should want scientific theories to be evaluated by thinking that is unbiased and logical. We should pursue this noble goal, using it as an aiming point and taking actions that will move us closer to it, while humbly recognizing that we haven't yet achieved it and never will. One way to minimize nonscientific influences is to make science more open-minded, allowing theory evaluation to be based on evidence and logic, not rules that can bypass the process of science and make evidence irrelevant. .....

Open Science is not Theistic Science
theistic science is based on the principle that "Christians ought to consult all they know or have reason to believe when forming and testing hypotheses, when explaining things in science, and when evaluating the plausibility of various scientific hypotheses. Among the things they should consult are propositions of theology. (J.P. Moreland & John Mark Reynolds; page 19 in Three Views of Creation, 2000)" Alvin Plantinga describes the rationality of adopting this approach: "a Christian academic and scientific community ought to pursue science in its own way, starting from and taking for granted what we know as Christians." In theistic science, a theistic worldview is used as a metaphysical foundation for doing science. But theistic science is not a single way of thinking, since it can lead to different theological propositions about God, nature, and science.
open science is open to different perspectives. In contrast with the current monopoly of naturalistic science (and education) that allows only one perspective, I'm advocating an open science that allows a variety of perspectives — including naturalism, intelligent design, and different types of theistic science — and is open-minded toward a range of scientific conclusions.

Scientific Objectivity: What is it?
Here are two ways to think about objectivity in science:
• One way to define objectivity, based on the premise that objectivity and flexibility are related, is to ask: "How strongly does a scientist hope that a theory evaluation will result in a particular conclusion?" or "Would a scientist be open-minded and willing to change views (if this is supported by the evidence and logic) and accept another theory?"
• Another definition is based on the premise that a conclusion would be more objective if it was produced by pure scientific logic, if cultural-personal factors exerted no influence during the process of evaluation. Just as Newton tried to imagine the characteristics of idealized motion without friction, we can try to imagine the characteristics of an idealized evaluation without cultural-personal influences, with only scientific logic.

Bias and Falsity
Even if scientists (as individuals or in a group) are motivated to be biased in a particular way, this does not mean that the process of scientific evaluation, or the conclusion reached, must be biased, or that the conclusion will be false.
I'll define an unbiased conclusion as one that matches the conclusion of an "idealized evaluation" when we ask, "If there was an objectively neutral evaluation of the evidence, based on logic rather than desires, what would be the conclusion?" There are two ways that biased scientists could reach an unbiased conclusion. • process: Perhaps the scientists can overcome their tendency toward bias, and can make an objective evaluation. • conclusion: Or a person (or group) may strongly hope the evidence will point to a certain conclusion, and they are incapable of making an objective evaluation, but the reality is that an objectively neutral evaluation of the evidence actually does point to the desired conclusion, so the scientist's bias (during the process of evaluation) makes no difference in the conclusion.
What about falsity? Perhaps the evidence "points to the desired conclusion" because it is true, because "the way they hope the world is" corresponds to "the way the world really is," so bias does not indicate falsity.
Therefore, we cannot say "If scientists have a motivation to be biased, their conclusion will be biased and will be wrong," since a biased motivation can lead to four types of conclusions: biased and wrong, biased yet true, unbiased yet wrong, unbiased and true.

Freedom and Necessity
Freedom: a Judeo-Christian theist has a wide range of options — in the many variations of theistic evolution (chemical and/or biological), old-earth creation (this is my view), or young-earth creation — and is free to follow the evidence and logic of science wherever it leads.
Necessity: by contrast, an atheist (or an inflexible agnostic who wants to remain agnostic) has no options and no scientific freedom, since only one conclusion is acceptable — some type of natural evolution (both chemical and biological) somewhere in the universe, with no action by God.

• And from the other side of the page, asking "Can science influence worldviews?",

Two Limits for Science
MN is a proposed limit (proposing "only natural causes in scientific theories") for what can claim to be science, while MN-Humility (acknowledging the possibility of unavoidable error) is a limit for what MN-Science can claim to explain.

A Change of Mind
In 1998, I was willing to support either of two approaches, as described in Section 1: an open search (with a combination of MN plus MN-Humility, using a closed MN-Science as one part of an open search for truth) or an open science (treating naturalism as a theory to be tested, not a conclusion to be accepted in science). Two years later, I concluded that it was more rational to reject rigid-MN, mainly because I had become convinced that — in a search for truth about nature — open science is better science, because we should let scientists use the entire process of science (including a logical evaluation of all competitive theories) when they are determining the conclusions of science. Otherwise, evaluative bias will occur because scholars who advocate an open search will have a strong tendency to reduce their cognitive dissonance (as individuals and as a community) by claiming, in the non-science phase of the open search, that "we would have reached the same conclusion in a testable-MN open science" instead of admitting that "maybe the rigid-MN closed science we're advocating is wrong."
Another reason to reject rigid-MN is the rarity and futility of humility.

The Futility of Humility
In principle, an open search (with MN-Science plus MN-Humility) is logically acceptable. In practice, usually the result is not satisfactory because even when MN-Humility is acknowledged (which is rare) it is not effective. Why?
Think about what happens when a "non-scientific" design theory and a "scientific" non-design theory both claim to describe the same event, such as the origin of life. Due to the cultural authority of science, the nonscientific theory is not respected because most people assume that, for a theory about nature, "not scientific" means "probably not true." Instead, the scientific theory is assumed to be more plausible, even if the scientific evidence does not support it. And in a classroom where "only science is taught," only the naturalistic non-design theory is taught, and it is taught as "the conclusion of science."

Methodology can influence Philosophy
In principle, methodology and worldview-philosophy can be independent. In practice, they are interactive and each influences the other.
In principle, an open search (conducted with MN-humility) can prevent the naturalistic methodology of MN-science from influencing our philosophical worldviews of "the way the world is, what is and isn't real, what can and cannot happen."
In practice, methodology often influences our thinking because naturalistic assumptions automatically become naturalistic conclusions about "the way the world is according to science," and many people are influenced by science.

Is methodological naturalism theologically acceptable?
In Section 1, I explain how "philosophical naturism differs from methodological naturalism in two ways" and why "in my opinion, there are two rational, theologically acceptable ways [open search or open science] for Christians to view methodological naturalism." But I also explain why, "although accepting MN can be rational and theologically acceptable for a Christian," I think an open science is preferable for two reasons: it is a more effective way to search for truth about nature; and, as explained in the two sections above (about the futility of humility and how methodology can influence philosophy), "in principle, an open search... can prevent the naturalistic methodology of MN-science from influencing our philosophical worldviews" but "in practice... naturalistic assumptions automatically become naturalistic conclusions about 'the way the world is according to science,' and many people are influenced by science."
For these two reasons, most proponents of Intelligent Design agree with William Dembski when he says, "The empirical evidence [for a naturalistic origin and development of life] is in fact weak, but the conclusion follows necessarily as a strict logical deduction once science is as a matter of definition restricted to undirected natural processes. ... There is a simple way out of this impasse [of illogical circular reasoning]: dump methodological naturalism," and a second reason-to-dump is because "methodological naturalism is the functional equivalent of a full blown metaphysical naturalism... once science comes to be taken as the only universally valid form of knowledge within a culture." (from Intelligent Design: The Bridge between Science & Theology, p 119) This important question — Are there two acceptable ways for a Christian to view methodological naturalism? — will be explored more fully (eventually but not yet) in a page about relationships between theistic evolution and intelligent design.