"Scientific enquiry rests upon the notion that all manifestations in the universe are explainable in natural terms, without supernatural intervention. Strictly speaking, this notion is not an a priori philosophical stand or profession of belief. It is a postulate, a working hypothesis that we should be prepared to abandon if faced with facts that defy every attempt at rational explanation. Many scientists, however, do not bother to make this distinction, tacitly extrapolating from hypothesis to affirmation. They are perfectly happy with the explanations provided by science. Like Laplace, they have no need for the 'God hypothesis' and equate the scientific attitude with agnosticism, if not with outright atheism. "
Life Evolving, New York: Oxford University Press, 2002 p. 284.
This version of methodological naturalism is provisional in nature. Lennox notices that de Duve conflates rational explanation with naturalistic explanations, to which he objects. However, for him, science has to try to stay within naturalism, but it is at least possible that it could be given up should the evidence point strongly toward the supernatural. Contrast this with Richard Lewontin:
‘Our willingness to accept scientific claims that are against common sense is the key to an understanding of the real struggle between science and the supernatural. We take the side of science in spite of the patent absurdity of some of its constructs, in spite of its failure to fulfill many of its extravagant promises of health and life, in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism.
It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated. Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door.
The eminent Kant scholar Lewis Beck used to say that anyone who could believe in God could believe in anything. To appeal to an omnipotent deity is to allow that at any moment the regularities of nature may be ruptured, that Miracles may happen.
Richard Lewontin, Billions and billions of demons (review of The Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan, 1997), The New York Review, p. 31, 9 January 1997.
If de Duve is an evidentialist naturalist, Lewontin is a presuppositionalist naturalist. Further, his methdological naturalism is absolute, not provisional. We cannot allow a Divine Foot in the door. We can call this absolutist methodological naturalism.
Finally, Methodological Naturalism can be not an absolute principle, but only a defining principle for the sciences. The Catholic philosopher of science Ernan McMullin writes:
But, of course, methodological naturalism does not restrict our study of nature; it just lays down which sort of study qualifies as scientific. If someone wants to pursue another approach to nature--and there are many others--the methodological naturalist has no reason to object. Scientists have to proceed in this way; the methodology of natural science gives no purchase on the claim that a particular event or type of event is to be explained by invoking God's creative action directly.
"Plantinga's Defense of Special Creation," Christian Scholar's Review [Sept. 1991], p. 57.
This is echoed in the Jones ruling.
Expert testimony reveals that since the scientific revolution of the 16th and 17th centuries, science has been limited to the search for natural causes to explain natural phenomena. …we find that while ID arguments may be true, a proposition on which the Court takes no position, ID is not science…ID violates the centuries-old ground rules of science by invoking and permitting supernatural causation…While supernatural explanations may be important and have merit, they are not part of science…This rigorous attachment to ‘natural’ explanations is an essential attribute to science by definition and by convention.
So, if you are recommending methodological naturalism, which one are you recommending?