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Metaphysical naturalism, also called ontological naturalism, philosophical naturalism and scientific materialism is a strong belief in naturalism, a worldview with a philosophical aspect which holds that there is nothing but natural elements, principles, and relations of the kind studied by the natural sciences, i.e., those required to understand our physical environment by mathematical modeling. In contrast, methodological naturalism is an assumption of naturalism as a methodology of science, for which metaphysical naturalism provides only one possible ontological foundation.
Metaphysical naturalism holds that all properties related to consciousness and the mind are reducible to, or supervene upon, nature. Broadly, the corresponding theological perspective is religious naturalism or spiritual naturalism. More specifically, it rejects the supernatural concepts and explanations that are part of many religions.
Metaphysical naturalism is a philosophy which maintains that nature encompasses all that exists throughout space and time. Nature (the universe or cosmos) consists only of natural elements, that is, of spatiotemporal physical substance—mass–energy. For example, astronomer Carl Sagan, an agnostic, described the cosmos as "all that is or ever was or ever will be." Non-physical or quasi-physical substance, such as information, ideas, values, logic, mathematics, intellect, and other emergent phenomena, either supervene upon the physical or can be reduced to a physical account. The supernatural does not exist, which is to say, only nature is real.
Naturalism, in recent usage, is a species of philosophical monism according to which whatever exists or happens is natural in the sense of being susceptible to explanation through methods which, although paradigmatically exemplified in the natural sciences, are continuous from domain to domain of objects and events. Hence, naturalism is polemically defined as repudiating the view that there exists or could exist any entities which lie, in principle, beyond the scope of scientific explanation.
— Arthur C. Danto, The Encyclopedia of Philosophy, Naturalism
According to Steven Schafersman, president of Texas Citizens for Science, an advocacy group opposing creationism in public schools, naturalism is a metaphysical philosophy opposed primarily by Biblical creationism."
Regarding the vagueness of the general term "naturalism", David Papineau traces the current usage to philosophers in early 20th century America such as John Dewey, Ernest Nagel, Sidney Hook and Roy Wood Sellars: "So understood, ‘naturalism’ is not a particularly informative term as applied to contemporary philosophers. The great majority of contemporary philosophers would happily accept naturalism as just characterized—that is, they would both reject ‘supernatural’ entities, and allow that science is a possible route (if not necessarily the only one) to important truths about the ‘human spirit’." Papineau remarks that philosophers widely regard naturalism as a "positive" term, and "few active philosophers nowadays are happy to announce themselves as ‘non-naturalists’", while noting that "philosophers concerned with religion tend to be less enthusiastic about ‘naturalism’" and that despite an "inevitable" divergence due to its popularity, if more narrowly construed, (to the chagrin of John McDowell, David Chalmers and Jennifer Hornsby, for example), those not so disqualified remain nonetheless content "to set the bar for ‘naturalism’ higher".
Philosopher and theologian Alvin Plantinga, a well-known critic of naturalism in general, comments: "Naturalism is presumably not a religion. In one very important respect, however, it resembles religion: it can be said to perform the cognitive function of a religion. There is that range of deep human questions to which a religion typically provides an answer ... Like a typical religion, naturalism gives a set of answers to these and similar questions."
Metaphysical naturalism is an approach to metaphysics or ontology, which deals with existence per se. It should not be confused with methodological naturalism, which sees empiricism as the basis for the scientific method. Immaterial entities can occur in a rational worldview (such as that of Plato, Aristotle, Aquinas, Newton or Darwin) which are deduced from empirical data and seen as integral to a complete understanding of natural operations.
Metaphysical naturalism regards nature as all that exists or can exist, and assumes that events in nature are explainable by empirically observable causes. However, various abstractions, such as numbers, are considered to be immaterial for practical purposes. (See Mathematical Platonism.)
Richard Carrier, in his book subtitled "A Defense of Metaphysical Naturalism", describes it as a philosophy "wherein worship is replaced with curiosity, devotion with diligence, holiness with sincerity, ritual with study, and scripture with the whole world and the whole of human learning". Carrier asserts that it is the naturalist’s duty "to question all things and have a well grounded faith in what is well-investigated and well-proved, rather than what is merely well-asserted or well-liked."
Some have charged that this focus on science is really a form of scientism. However, other fields besides science (e.g., history) sometimes find acceptance with metaphysical naturalists. Metaphysical naturalism is an approach to metaphysics or ontology. These subjects deal with existence per se.
Science and naturalism 
While not metaphysical naturalism per se, in the more general sense of naturalism and philosophy expressed by Kate and Vitaly (2000) "there are certain philosophical assumptions made at the base of the scientific method - namely, that reality is objective and consistent, that humans have the capacity to perceive reality accurately, and that rational explanations exist for elements of the real world. These assumptions are the basis of naturalism, the philosophy on which science is grounded." As noted by Steven Schafersman, methodological naturalism is "the adoption or assumption of philosophical naturalism within scientific method with or without fully accepting or believing it ... science is not metaphysical and does not depend on the ultimate truth of any metaphysics for its success (although science does have metaphysical implications), but methodological naturalism must be adopted as a strategy or working hypothesis for science to succeed. We may therefore be agnostic about the ultimate truth of naturalism, but must nevertheless adopt it and investigate nature as if nature is all that there is." Contrary to other notable opponents of teaching Creationism or Intelligent Design in US public schools such as Eugenie Scott, Schafersman asserts that "while science as a process only requires methodological naturalism, I think that the assumption of methodological naturalism by scientists and others logically and morally entails ontological naturalism." as well as the similarly controversial assertion: "I maintain that the practice or adoption of methodological naturalism entails a logical and moral belief in ontological naturalism, so they are not logically decoupled." On the other hand, Scott argues:
that a clear distinction must be drawn between science as a way of knowing about the natural world and science as a foundation for philosophical views. One should be taught to our children in school, and the other can optionally be taught to our children at home. Once this view is explained, I have found far more support than disagreement among my university colleagues. Even someone who may disagree with my logic or understanding of philosophy of science often understands the strategic reasons for separating methodological from philosophical materialism — if we want more Americans to understand evolution.—Eugenie C. Scott, Science and Religion, Methodology and Humanism
However, there are other controversies, Arthur Newell Strahler embeds peculiar anthropic distinctions in the name of naturalism: "The naturalistic view is that the particular universe we observe came into existence and has operated through all time and in all its parts without the impetus or guidance of any supernatural agency. The naturalistic view is espoused by science as its fundamental assumption." Variously known as background independence, the cosmological principle, the principle of universality, the principle of uniformity, or uniformitarianism, there are important philosophical assumptions that cannot be derived from nature. As noted by Stephen Jay Gould: "You cannot go to a rocky outcrop and observe either the constancy of nature's laws or the working of unknown processes. It works the other way around." You first assume these propositions and "then you go to the out crop of rock." "The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference which, as Bacon showed nearly four hundred years ago, is the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown and, therefore, no way of reaching general conclusions from a finite number of observations. (Since the assumption is itself vindicated by induction, it can in no way “prove” the validity of induction - an endeavor virtually abandoned after Hume demonstrated its futility two centuries ago)." Gould also notes that natural processes such as Lyell's “uniformity of process” are an assumption: “As such, it is another a priori assumption shared by all scientists and not a statement about the empirical world.” Such assumptions across time and space are needed for scientists to extrapolate into the unobservable past, according to G.G. Simpson: "Uniformity is an unprovable postulate justified, or indeed required, on two grounds. First, nothing in our incomplete but extensive knowledge of history disagrees with it. Second, only with this postulate is a rational interpretation of history possible, and we are justified in seeking—as scientists we must seek—such a rational interpretation." and according to R. Hooykaas: "The principle of uniformity is not a law, not a rule established after comparison of facts, but a principle, preceding the observation of facts . . . It is the logical principle of parsimony of causes and of economy of scientific notions. By explaining past changes by analogy with present phenomena, a limit is set to conjecture, for there is only one way in which two things are equal, but there are an infinity of ways in which they could be supposed different."
The mind is caused by natural phenomena 
What all metaphysical naturalists agree on, however, is that the fundamental constituents of reality, from which everything derives and upon which everything depends, are fundamentally natural. So if any variety of metaphysical naturalism is true, any mental properties that exist are caused by and ontologically dependent upon nature. However, some metaphysical naturalists consider the mental to be out-of-bounds, just like the supernatural.[verification needed]
Origins and relation with other doctrines 
Regarding science and evolution, Eugenie C. Scott, a notable opponent of teaching creationism or intelligent design in US public schools, stresses the importance of separating metaphysical from methodological naturalism:
If it is important for Americans to learn about science and evolution, decoupling the two forms of naturalism is essential strategy. ... I suggest that scientists can defuse some of the opposition to evolution by first recognizing that the vast majority of Americans are believers, and that most Americans want to retain their faith. It is demonstrable that individuals can retain religious beliefs and still accept evolution as science. Scientists should avoid confusing the methodological naturalism of science with metaphysical naturalism.—Eugenie C. Scott, Creationism, Ideology, and Science
According to Steven Schafersman, president of Texas Citizens for Science, an advocacy group opposing creationism in public schools, the progressive adoption of methodological naturalism—and later of metaphysical naturalism—followed the advances of science and the increase of its explanatory power. These advances also caused the diffusion of positions associated with metaphysical naturalism, such as existentialism.
According to David Papineau, contemporary naturalism is a consequence of the build-up of scientific evidence during the twentieth century for the "causal closure of the physical", the doctrine that all physical effects can be accounted for by physical causes.
By the middle of the twentieth century, the acceptance of the causal closure of the physical realm led to even stronger naturalist views. The causal closure thesis implies that any mental and biological causes must themselves be physically constituted, if they are to produce physical effects. It thus gives rise to a particularly strong form of ontological naturalism, namely the physicalist doctrine that any state that has physical effects must itself be physical.
From the 1950s onwards, philosophers began to formulate arguments for ontological physicalism. Some of these arguments appealed explicitly to the causal closure of the physical realm (Feigl 1958, Oppenheim and Putnam 1958). In other cases, the reliance on causal closure lay below the surface. However, it is not hard to see that even in these latter cases the causal closure thesis played a crucial role.—David Papineau, "Naturalism" in the Stanford Encyclopedia of Philosophy
Evolutionary criticism 
Contemporary naturalists possess a wide diversity of beliefs within metaphysical naturalism.
Undesigned universe 
Naturalists argue that the universe has either always existed or had a purely natural origin, being neither created nor designed.
Abiogenesis and evolution 
Since nature is all there is, and there was once no life, abiogenesis is implied: that life arose spontaneously from natural causes. Naturalists reason about how, not if evolution happened. They maintain that humanity's existence is not by intelligent design but rather a natural process of emergence. Although naturalists do not interpret evolution as purpose driven, some nonetheless embrace virtue ethics and many see no compelling argument against ethical naturalism.[verification needed]
Mind as brain 
Metaphysical naturalists do not believe in a soul or spirit, nor in ghosts, and when explaining what constitutes the mind they rarely appeal to substance dualism. If one's mind, or rather one's identity and existence as a person, is entirely the product of natural processes, three conclusions follow according to W.T. Stace. First, all mental contents (such as ideas, theories, emotions, moral and personal values, or aesthetic response) exist solely as computational constructions of one's brain and genetics, not as things that exist independently of these. Second, damage to the brain (regardless of how) should be of great concern. Third, death or destruction of one's brain cannot be survived, which is to say, all humans are mortal. Stace, however, believes that ecstatic mysticism calls into question the assumption that awareness is impossible without data processing.
Utility of reason 
Metaphysical naturalists hold that reason is the refinement and improvement of naturally evolved faculties. The certitude of deductive logic remains unexplained by this essentially probabilistic view. Nevertheless, naturalists believe anyone who wishes to have more beliefs that are true than are false should seek to perfect and consistently employ their reason in testing and forming beliefs. Empirical methods (especially those of proven use in the sciences) are unsurpassed for discovering the facts of reality, while methods of pure reason alone can securely discover logical errors.
Value of society 
Humans are social animals, which is why humanity developed culture and civilization. In terms of evolution, this means that differential reproductive success somehow depended on traits that permit the development and maintenance of a healthy and productive culture and civilization.
Ancient period 
Metaphysical naturalism appears to have originated in early Greek philosophy. The earliest presocratic philosophers, such as Thales, Anaxagoras or especially the atomist Democritus, were labeled by their peers and successors "the physikoi" (from the Greek φυσικός or physikos, meaning "natural philosopher," borrowing on the word φύσις or physis, meaning "nature") because they investigated natural causes, often excluding any role for gods in the creation or operation of the world. This eventually led to fully developed systems such as Epicureanism, which sought to explain everything that exists as the product of atoms falling and swerving in a void.
Plato's world of eternal and unchanging Forms, imperfectly represented in matter by a divine Artisan, contrasts sharply with the various mechanistic Weltanschauungen, of which atomism was, by the fourth century at least, the most prominent... This debate was to persist throughout the ancient world. Atomistic mechanism got a shot in the arm from Epicurus... while the Stoics adopted a divine teleology... The choice seems simple: either show how a structured, regular world could arise out of undirected processes, or inject intelligence into the system. This was how Aristotle (384–322 bc), when still a young acolyte of Plato, saw matters. Cicero (On the Nature of the Gods 2. 95 = Fr. 12) preserves Aristotle's own cave-image: if troglodytes were brought on a sudden into the upper world, they would immediately suppose it to have been intelligently arranged. But Aristotle grew to abandon this view; although he believes in a divine being, the Prime Mover is not the efficient cause of action in the Universe, and plays no part in constructing or arranging it... But, although he rejects the divine Artificer, Aristotle does not resort to a pure mechanism of random forces. Instead he seeks to find a middle way between the two positions, one which relies heavily on the notion of Nature, or phusis.—R. J. Hankinson, Cause and Explanation in Ancient Greek Thought
Metaphysical naturalism is most notably a Western phenomenon, but an equivalent idea has long existed in the East. Though unnamed and never articulated into a coherent system, one tradition within Confucian philosophy embraced a view that can be called metaphysical naturalism, dating back at least to Wang Chong in the 1st century, if not earlier. But this tradition arose independently and had little influence on the development of modern naturalist philosophy or on Eastern or Western culture.
Middle ages to modernity 
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With the rise and dominance of Christianity in the West and the later spread of Islam, metaphysical naturalism was generally abandoned by intellectuals. Thus, there is little evidence for it in the Middle Ages. The reintroduction of Aristotle's empirical epistemology as well as previously lost treatises by Greco-Roman natural philosophers during the Renaissance contributed to Scientific Revolution which was begun by the medieval Scholastics without resulting in any noticeable increase in commitment to naturalism. It was not until the early modern era and Age of Enlightenment that naturalism, like that of Benedict Spinoza, David Hume, Denis Diderot, Julien La Mettrie, and Baron d'Holbach, among others, started to emerge again in the 17th and 18th centuries.
In this period, some metaphysical naturalists adhered to a distinct doctrine, materialism, which became the only category of metaphysical naturalism widely defended until the 20th century, when advances in physics resulted in widespread abandonment of prior formulations of materialism. 19th century physics added electromagnetic force fields, and in the 20th century matter was found to be a form of energy and therefore not fundamental as materialists had assumed. (See History of physics.) In philosophy, renewed attention to the problem of universals, philosophy of mathematics, the development of mathematical logic, and the post-positivist revival of metaphysics and the philosophy of religion, initially by way of Wittgensteinian linguistic philosophy, further called the naturalistic paradigm into question. Developments such as these, along with those within science and the philosophy of science brought new advancements and revisions of naturalistic doctrines by naturalistic philosophers into metaphysics, ethics, the philosophy of language, the philosophy of mind, epistemology, etc., the products of which include physicalism and eliminative materialism, supervenience, causal theories of reference, anomalous monism, naturalized epistemology (e.g. reliabilism), internalism and externalism, ethical naturalism, and property dualism, for example.
Currently, metaphysical naturalism is more widely embraced than in previous centuries, especially but not exclusively in the natural sciences and the Anglo-American, analytic philosophical communities. While the vast majority of the population of the world remains firmly committed to non-naturalistic worldviews, prominent contemporary defenders of naturalism and/or naturalistic theses and doctrines today include J. J. C. Smart, David Malet Armstrong, David Papineau, Paul Kurtz, Brian Leiter, Daniel Dennett, Michael Devitt, Fred Dretske, Paul and Patricia Churchland, Mario Bunge, Jonathan Schaffer, Hilary Kornblith, Quentin Smith, Paul Draper, Michael Martin, among many other academic philosophers.
Marxism, Objectivism, and secular humanism 
A number of politicized versions of naturalism have arisen in the Western world, most notably Marxism in the 19th century and Objectivism in the 20th century. Marxism is an expression of communist or socialist idealism within a naturalistic framework. Objectivism is an expression of capitalist idealism within a naturalistic framework. Most proponents of metaphysical naturalism in First World countries, however, are not Marxists nor Objectivists, and instead embrace the more moderate political ideals of secular humanism or cultural moral relativism.
Arguments for metaphysical naturalism 
Arguments for metaphysical naturalism include the following.
Argument from physical minds 
In the context of creation and evolution debates, Internet Infidels co-founder Jeffery Jay Lowder argues against what he calls "the argument from bias", that a priori, the supernatural is merely ruled out due to an unexamined stipulation. Lowder believes "there are good empirical reasons for believing that metaphysical naturalism is true, and therefore a denial of the supernatural need not be based upon an a priori assumption". He offers two arguments against theism as empirical evidence, the argument from evil and Michael Tooley's and Paul Draper's argument from physical minds: "Since all known mental activity has a physical basis, there are probably no disembodied minds. But God is conceived of as a disembodied mind. Therefore, God probably does not exist." Lowder argues the correlation between mind and brain implies that supernatural souls do not exist because the theist position, according to Lowder, is that the mind depends upon this soul instead of the brain.
Cosmological argument for naturalism 
[Elegance] goes directly to the question of how the laws of nature are constructed. Nobody knows the answer to that. Nobody! It's a perfectly legitimate hypothesis, in my view, to say that some extremely elegant creator made those laws. But I think if you go down that road, you must have the courage to ask the next question, which is: Where did that creator come from? And where did his, her, or its elegance come from? And if you say it was always there, then why not say that the laws of nature were always there and save a step?—Carl Sagan, Conversations with Carl Sagan
Arguments against metaphysical naturalism 
Arguments against metaphysical naturalism include the following examples.
Evolutionary argument against naturalism 
Alvin Plantinga is a Professor of Philosophy now at Calvin College, a Christian, and a well-known critic of naturalism. He argues, in his evolutionary argument against naturalism, that the probability that evolution has produced humans with reliable true beliefs, is low or inscrutable, unless their evolution was guided, for example, by God. According to David Kahan of the University of Glasgow, in order to understand how beliefs are warranted, a justification must be found in the context of supernatural theism, as in Plantinga's epistemology. (See also supernormal stimuli).
Plantinga argues that together, naturalism and evolution provide an insurmountable "defeater for the belief that our cognitive faculties are reliable", i.e., a skeptical argument along the lines of Descartes' Evil demon or Brain in a vat.
Take philosophical naturalism to be the belief that there aren't any supernatural entities--no such person as God, for example, but also no other supernatural entities, and nothing at all like God. My claim was that naturalism and contemporary evolutionary theory are at serious odds with one another--and this despite the fact that the latter is ordinarily thought to be one of the main pillars supporting the edifice of the former. (Of course I am not attacking the theory of evolution, or anything in that neighborhood; I am instead attacking the conjunction of naturalism with the view that human beings have evolved in that way. I see no similar problems with the conjunction of theism and the idea that human beings have evolved in the way contemporary evolutionary science suggests.) More particularly, I argued that the conjunction of naturalism with the belief that we human beings have evolved in conformity with current evolutionary doctrine… is in a certain interesting way self-defeating or self-referentially incoherent.—Alvin Plantinga, "Introduction" in Naturalism Defeated?: Essays on Plantinga's Evolutionary Argument Against Naturalism
Branden Fitelson of the University of California, Berkeley and Elliott Sober of the University of Wisconsin–Madison argue that Plantinga must show that the combination of evolution and naturalism also defeats the more modest claim that "at least a non-negligible minority of our beliefs are true", and that defects such as cognitive bias are nonetheless consistent with being made in the image of a rational God. Whereas evolutionary science already acknowledges that cognitive processes are unreliable, including the fallibility of the scientific enterprise itself, Plantinga's hyperbolic doubt is no more a defeater for naturalism than it is for theistic metaphysics founded upon a non-deceiving God who designed the human mind: "[neither] can construct a non-question-begging argument that refutes global skepticism." Plantinga's argument has also been criticized by philosopher Daniel Dennett and historian Richard Carrier who argue that a cognitive apparatus for truth-finding can result from natural selection.
See also 
Further reading 
Historical overview 
- Edward B. Davis and Robin Collins, "Scientific Naturalism." In Science and Religion: A Historical Introduction, ed. Gary B. Ferngren, Johns Hopkins University Press, 2002, pp. 322–34.
- Gary Drescher, Good and Real, The MIT Press, 2006. [ISBN 0-262-04233-9]
- David Malet Armstrong, A World of States of Affairs, Cambridge: Cambridge University Press, 1997. [ISBN 0-521-58064-1]
- Mario Bunge, 2006, Chasing Reality: Strife over Realism, University of Toronto Press. ISBN 0-8020-9075-3 and 2001, Scientific Realism: Selected Essays of Mario Bunge, Prometheus Books. ISBN 1-57392-892-5
- Richard Carrier, 2005, Sense and Goodness without God: A Defense of Metaphysical Naturalism, AuthorHouse. ISBN 1-4208-0293-3
- Mario De Caro & David Macarthur (eds), 2004. Naturalism in Question. Cambridge, Mass: Harvard University Press. ISBN 0-674-01295-X
- Daniel Dennett, 2003, Freedom Evolves, Penguin. ISBN 0-14-200384-0 and 2006
- Andrew Melnyk, 2003, A Physicalist Manifesto: Thoroughly Modern Materialism, Cambridge University Press. ISBN 0-521-82711-6
- David Mills, 2004, Atheist Universe: Why God Didn't Have A Thing To Do With It, Xlibris. ISBN 1-4134-3481-9
- Jeffrey Poland, 1994, Physicalism: The Philosophical Foundations, Oxford University Press. ISBN 0-19-824980-2
- James Beilby, ed., 2002, Naturalism Defeated? Essays on Plantinga's Evolutionary Argument Against Naturalism, Cornell University Press. ISBN 0-8014-8763-3
- William Lane Craig and J.P. Moreland, eds., 2000, Naturalism: A Critical Analysis, Routledge. ISBN 0-415-23524-3
- Stewart Goetz and Charles Taliaferro, 2008, Naturalism, Eerdmans Publishing. ISBN 978-0-8028-0768-7
- Phillip E. Johnson, 1998, Reason in the Balance: The Case Against Naturalism in Science, Law & Education, InterVarsity Press. ISBN 0-8308-1929-0 and 2002, The Wedge of Truth: Splitting the Foundations of Naturalism, InterVarsity Press. ISBN 0-8308-2395-6
- C.S. Lewis, ed., 1996, "Miracles", Harper Collins. ISBN 0-06-065301-9
- Michael Rea, 2004, World without Design: The Ontological Consequences of Naturalism, Oxford University Press. ISBN 0-19-924761-7
- Victor Reppert, 2003, C.S. Lewis's Dangerous Idea: In Defense of the Argument from Reason, InterVarsity Press. ISBN 0-8308-2732-3
- Mark Steiner, 2002, The Applicability of Mathematics as a Philosophical Problem, Harvard University Press. ISBN 0-674-00970-3
- Sagan 2002, p. 1.
- Schafersman 1996.
- Stone 2008, p. 2 "Personally, I place great emphasis on the phrase “in principle,” since there are many things that science does not now explain. And perhaps we need some natural piety concerning the ontological limit question as to why there is anything at all. But the idea that naturalism is a polemical notion is important."
- Williams, Sally (July 4, 2007). "The God curriculum". London: The Telegraph. Retrieved 2008-12-26.
- Papineau 2007.
- Plantinga 2010
- Carrier 2005, p. 26
- Rea 2002
- Clark 2008
- "Since philosophy is at least implicitly at the core of every decision we make or position we take, it is obvious that correct philosophy is a necessity for scientific inquiry to take place." (A.Sergei 2000)
- Scott, Eugenie C. (2008). "Science and Religion, Methodology and Humanism". NCSE. Retrieved 20 March 2012.
- Scott, Eugenie C. (1996). "Creationism, Ideology, and Science". In Gross, Levitt, and Lewis. The Flight From Science and Reason. The New York Academy of Sciences,. pp. 519–520.
- (Strahler 1992, p. 3)
- (Gould 1987, p. 120)
- Gould 1987, p. 119
- (Gould 1965, pp. 223–228)
- (Gould 1984, p. 11)
- Simpson 1963, pp. 24–48
- Hooykaas 1963, p. 38
- Richard Carrier, On Defining Naturalism as a Worldview, Free Inquiry 30.3 (April/May 2010), pp. 50-51.
- Carrier 2005, pp. 211–212
- Schafersman, Steven D. (1996). "Naturalism is Today An Essential Part of Science". Section "The Origin of Naturalism and Its Relation to Science". "Naturalism did not exist as a philosophy before the nineteenth century, but only as an occasionally adopted and non-rigorous method among natural philosophers. It is a unique philosophy in that it is not ancient or prior to science, and that it developed largely due to the influence of science."
- Schafersman, Steven D. (1996). "Naturalism is Today An Essential Part of Science". Section "The Origin of Naturalism and Its Relation to Science". "Naturalism is almost unique in that it would not exist as a philosophy without the prior existence of science. It shares this status, in my view, with the philosophy of existentialism."
- Rosenberg, Alexander (2009). "The Disenchanted Naturalist’s Guide to Reality". On the Human Forum. National Humanities Center (United States).
- Papineau, David (2007). "Naturalism". In Edward N. Zalta. Stanford Encyclopedia of Philosophy. "It thus gives rise to a particularly strong form of ontological naturalism, namely the physicalist doctrine that any state that has physical effects must itself be physical."
- Schafersman, Steven D. (1996). "Naturalism is Today An Essential Part of Science". Section "The Origin of Naturalism and Its Relation to Science". "Certainly most philosophical naturalists today are materialists[...]"
- Augustine, Keith (2001). "A Defense of Naturalism". Secular Web. "In metaphysics, naturalism typically takes a form of materialism or physicalism[...]"
- Carrier 2005, pp. 166–68
- Richard Carrier, [The Argument from Biogenesis: Probabilities Against a Natural Origin of Life], Biology and Philosophy 19.5 (November 2004), pp. 739-64.
- Carrier 2005, pp. 168–176, 326–327
- Stace, W.T, Mysticism and Philosophy. N.Y.: Macmillan, 1960; reprinted, Los Angeles: Jeremy P. Tarcher, 1987.
- Carrier 2005, pp. 53–54
- Hankinson, R. J. (1997). Cause and Explanation in Ancient Greek Thought. Oxford University Press. p. 125. ISBN 978-0-19-924656-4.
- Lowder, Jeffery Jay (March 1999). "The Empirical Case for Metaphysical Naturalism". Internet Infidels Newsletter.
- "Argument from Physical Minds".
- Sagan, C.; Head, T. (2006). Conversations with Carl Sagan. Literary Conversations Series. University Press of Mississippi. p. 14. ISBN 9781578067367. LCCN 2005048747.
- "Gifford Lecture Series - Warrant and Proper Function 1987-1988".
- Plantinga, Alvin (11 April 2010). "Evolution, Shibboleths, and Philosophers — Letters to the Editor". The Chronicle of Higher Education. "…I do indeed think that evolution functions as a contemporary shibboleth by which to distinguish the ignorant fundamentalist goats from the informed and scientifically literate sheep.
According to Richard Dawkins, 'It is absolutely safe to say that, if you meet somebody who claims not to believe in evolution, that person is ignorant, stupid, or insane (or wicked, but I'd rather not consider that).' Daniel Dennett goes Dawkins one (or two) further: 'Anyone today who doubts that the variety of life on this planet was produced by a process of evolution is simply ignorant—inexcusably ignorant.' You wake up in the middle of the night; you think, can that whole Darwinian story really be true? Wham! You are inexcusably ignorant.
I do think that evolution has become a modern idol of the tribe. But of course it doesn't even begin to follow that I think the scientific theory of evolution is false. And I don't."
- Plantinga, Alvin (1993). Warrant and Proper Function. Oxford: Oxford University Press. Chap. 11. ISBN 0-19-507863-2.
- Beilby, J.K. (2002). "Introduction by Alvin Plantinga". Naturalism Defeated?: Essays on Plantinga's Evolutionary Argument Against Naturalism. Reference, Information and Interdisciplinary Subjects Series. Ithaca: Cornell University Press. pp. 1–2, 10. ISBN 978-0-8014-8763-7. LCCN 2001006111.
- Fitelson, Branden; Elliott Sober (1998). "Plantinga's Probability Arguments Against Evolutionary Naturalism". Pacific Philosophical Quarterly 79 (2): 115–129. doi:10.1111/1468-0114.00053. Retrieved 2007-03-06.
- Carrier 2005, pp. 181–188
- Audi, Robert (1996). "Naturalism". In Borchert, Donald M. The Encyclopedia of Philosophy Supplement. USA: Macmillan Reference. pp. 372–374.
- Carrier, Richard (2005). Sense and Goodness without God: A defense of Metaphysical Naturalism. AuthorHouse. p. 444. ISBN 1-4208-0293-3.
- Gould, Stephen J. (1984). "Toward the vindication of punctuational change in catastrophes and earth history". In Bergren, W. A.; Van Couvering, J. A. Catastrophes and Earth History. Princeton, New Jersey: Princeton University Press.
- Gould, Stephen J. (1987). Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time. Cambridge, MA: Harvard University Press. p. 119.
- Danto, Arthur C. (1967). "Naturalism". In Edwords, Paul. The Encyclopedia of Philosophy. New York: The Macmillan Co. and The Free Press. pp. 448–450.
- Hooykaas, R. (1963). The principle of uniformity in geology, biology, and theology (2nd ed.). London: E.J. Brill.
- Kurtz, Paul (1990). Philosophical Essays in Pragmatic Naturalism. Prometheus Books.
- Lacey, Alan R. (1995). "Naturalism". In Honderich, Ted. The Oxford Companion to Philosophy. Oxford University Press. pp. 604–606.
- Post, John F. (1995). "Naturalism". In Audi, Robert. The Cambridge Dictionary of Philosophy. Cambridge University Press. pp. 517–518.
- Rea, Michael (2002). World Without Design: The Ontological Consequences of Naturalism. Oxford University Press. ISBN 0-19-924760-9.
- Sagan, Carl (2002). Cosmos. Random House. ISBN 978-0-375-50832-5.
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