Metaphysical Naturalism

Metaphysical Naturalism

Metaphysical naturalism, also called ontological naturalism and philosophical naturalism 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.

Definition

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 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.

Worship

Metaphysical naturalism is 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," and 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."

Epistemology

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. Metaphysical naturalism is sometimes confused with methodological naturalism.

Science and Naturalism

While not metaphysical naturalism per see, in the more general sense of naturalism and philosophy expressed by Kate amd 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.

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 Alexander Rosenberg, naturalists, in general, have to accept moral nihilism.

By the middle of the twentieth century, the acceptance of the casual sic 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

Most metaphysical naturalists have adopted some form of materialism or physicalism.

Evolutionary Criticism

Contemporary naturalists possess a wide diversity of beliefs and engage each other in healthy debate and disagreement on many issues.

Undesigned Universe

Naturalists argue that the universe has either always existed or had a purely natural origin, being neither created nor designed. It has been asserted that the Big Bang cosmology was developed within this assumption, proposing that the observable universe had a beginning, unfolding from a process of natural laws. In fact, it was championed by a Belgian Catholic priest, Georges Lemaître and criticized by naturalists for being "too Biblical."

Deep Time

Deep time is the concept that the Geologic time scale is vast because the Earth is very old. It is measured in billions of years. "By recognizing the vastness of Earth history compared to human history, we internalize what John McPhee has termed Deep Time".

Abiogenesis and Evolution

Since there was once no life but now there is, without creative gods, then abiogenesis (life arising from inorganic compounds through natural causes) must have happened (although there are several current hypotheses about how). As the preconditions of abiogenesis currently appear to be statistically rare in the universe, some scientists argue that life's existence is therefore too lucky to be true, rather it must have been planned or intended. Likewise, since there were once only simple life forms and now there is a rich diversity of life on Earth, evolution by natural selection or other means is a fact. Naturalists hypothesize about how, not if evolution happened. They maintain that humanity's existence as rational animals 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.

Mind as Brain

Metaphysical naturalists don't believe in the soul or spirit, nor do they believe in ghosts and when explaining what constitutes the mind they rarely, if ever, 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, through discovering, then learning, and then employing methods and procedures that are found to increase the frequency with which one arrives at true conclusions and correct information about oneself and the universe. The certitude of deductive logic remains unexplained by this essentially probabilistic view. Nevertheless, naturalists believe that reason is superior to all the other tools available in ascertaining the truth, so 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.

History

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

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 eraand 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. 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 thephilosophy 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 sciencesand 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

There are many arguments for belief in metaphysical naturalism. Only a few will be surveyed here, and only in brief. There are many others, but most involve refinements, variants or sub-arguments to the following.

Argument From Precedent

For over three hundred years empirical methods have consistently discovered only natural things and causes, even underlying many things once thought to be supernatural. Meanwhile, no other methods have produced any consistent conclusions about the substance or causes of anything, much less anything supernatural. The logical inference is that since countless past gaps in knowledge have been filled by naturalism, and by nothing else, probably all remaining gaps in knowledge will be filled by naturalism as well. This simply extends a principle fundamental to science as a whole, that we should presume any new phenomenon obeys known laws of physics until we have empirically proven otherwise. Hence we should presume that any unexplained fact has a natural explanation until we have empirically proven otherwise. Therefore, since we have not found empirical proof of anything supernatural, and since we have abundant reason from past precedent to expect that natural explanations underlie everything, metaphysical naturalism is most probably true.

There are two unanswered objections to this argument. The first is that empirical methods restrict human experience to what is external and measurable without showing that only what is external and measurable exists. The argument is thus founded on an anti-empirical, a priorirejection of entire areas of human experience. The second is that in past applications of physics, what was to be explained was empirically measurable, whereas what naturalists claim can be explained by physics (intentions, awareness as opposed or data processing, God) are not empirically measurable and physics has never claimed that it is applicable to them. It must be recalled that physics uses abstractions, and that abstractions necessarily abstract from some data in order to focus on other data. Methods are not automatically applicable until empirically proven otherwise, but have conditions of applicability which must be met in advance of applying them. For example, no amount of empirical data will ever show that 2 + 2 = 4 always and everywhere.

Argument to Naturalism as Best Explanation

Some naturalists argue that sound naturalist hypotheses about facts still scientifically unexplained outperform all other hypotheses in explanatory scope and power, relative to explanatory simplicity. If that's true, then metaphysical naturalism is the best explanation of everything we observe and experience, and is therefore probably true. This amounts to arguing that everything makes more sense if naturalism is true, many details about ourselves and the world are more probable if naturalism is true, and to explain even the most mysterious of facts naturalism has to resort to fewer ad hoc assumptions than any known alternative. For example, resorting to the supernatural as explanation typically requires an array of completely ad hoc assumptions about the abilities, nature, limitations, and desires of supernatural forces. Even so, much of what remains unexplained is then elucidated as simply the "mystery" of the enigmatic will of the supernatural or as beyond human ken. Naturalism, on the other hand, relies much more heavily on assumptions already scientifically established as precedents and principles, and makes more specific predictions about what the observed results would be if naturalism were true, which align very well with actual observations.

This argument assumes that the hypothetico-deductive method is the only way to truth. Furthermore, this argument does draw an equivalence between methodological naturalism which focuses on epistemology with ontological naturalism which focuses on metaphysics. Whilst methodological naturalism has produced great success in explaining observed phenomena by testing hypotheses according to natural laws, this does not preclude on a priori grounds the possibility of supernatural phenomena existing within the universe. In addition, if something purported to be "supernatural" was confirmed by scientific observations, naturalists would discount these as anomalies or unexplained natural events. Empiricists place experience above theory, but naturalists reject whole classes of data based on an a prioriontological theory. Natural philosophers, from Aristotle on, have claimed that the facts of experience are adequate to deduce the existence of the metaphysical, not as hypothesis, but as a rational certainty entailed by observable facts. Regarding theology, a subject that Aristotle considered to be within the scope of Natural science or Physics, he observed that merely requiring one of something is, in general, a more parsimonious explanation than requiring many. However, not unlike later physicists, he was trying to explain the eternal circular motion of the planets and stars by reason of one or more instances of an unchanging principle. In a more recognizably theological argument, Thomas Aquinas reasoned deductively for additional properties that characterized a creator God.

Argument From Absence

One major way in which naturalism is claimed to explain things better than alternatives is that if the supernatural exists (whether as gods, powers, or spirits), it is so silent and inert that its effects are almost never observed, despite vast and extensive searching. Even the relatively few alleged observations take place only under dubious conditions lacking in sound empirical controls or tests, and on those occasions when they are subsequently subjected to sound controls or tests, they turn out to be false. Our inability to uncover clear evidence of anything supernatural is somewhat improbable if anything supernatural exists, but very probable if nothing supernatural exists, and therefore metaphysical naturalism is probably true.

This argument is met by the case built by theists such as Aristotle, Ibn Sina, and Aquinas that the entire natural world is an effect of and evidence for the Existence of God. If this argument is to be made, it should include a refutation of arguments purporting to show that all of nature is evidence.

Argument From Physical Minds

Neuroscientists have accumulated vast evidence that the functions and activities of the human mind correspond to the functions and activities of the human brain, which is constructed from different interacting physical systems that evolved over time through the animal kingdom. Our brains are now the most complex machines found anywhere in nature, and our minds appear limited to our brain's physical needs and capabilities. We have discovered no clear evidence of any other kind of mind, no clear evidence that our minds can exceed the limitations of our physical brain, and no clear evidence that all of the structures and functions of the brain did not slowly evolve through billions of years of undirected mutation and indifferent natural selection. This is the only way we would observe the facts to be if naturalism were true (since there is no other way to have a mind on naturalism except as the product of a slowly evolved, highly complex physical system like our brain), but if supernatural entities or processes exist (and some minds or mental content exist independently of a physical machine, like our brain), then what we observe is not the only way things could be (since by now we could have and likely would have observed some supernatural elements of our own or other minds or observed mental powers in other objects). Since this observation is less probable if supernaturalism is true, metaphysical naturalism is more likely to be true.

This argument presupposes that the mind consists of data processing only, which is what has been investigated and shown to be possible in physical systems such as computers. However, we know that most data processing in the brain occurs absent awareness, so it is fallacious to assume that awareness is a side effect of data processing. Since the primary function of the mind is to know, and knowing requires awareness of the known contents, naturalism has not provided an explanation of mind, but only of its data processing subsystem. If that subsystem is traumatized, what we are aware of may be defective, but that does not show that the existence of subjective awareness is a consequent of data processing.

Cosmological Argument for Naturalism

If naturalism is true, then the formation of intelligent life via natural processes in any one given small corner of a young universe is unlikely. Therefore, the only way we would observe life to exist if naturalism were true, is if the universe were old enough and of sufficient size that events of such an improbability would be very rare but still likely to occur. We observe the universe to be immensely old and large with life that is, as far as our observations allow, very rare. In addition, the universe is almost entirely lethal to life. By far most of what exists is a deadly radiation-filled vacuum, and by far most matter in the cosmos composes lethal environments like stars and black holes. Insofar as supernaturalism allows other possible arrangements for us to observe, such as universes more universally hospitable to life, universes far too young or small to produce life by mechanical accident, or universes in which life is far more common, what we observe to be the case is less probable given supernaturalism than given naturalism; therefore, metaphysical naturalism is more likely to be true.

Criticisms

It seems difficult to see how this argument supports naturalism. Naturalism does not, in itself, predict that the universe is old, nor does theism necessarily predict that it is young. If the laws of nature and the initial conditions of the universe were such that intelligent life evolved quickly, naturalists would still explain that observation by laws of nature and assume that those laws are independent of a deity. Similarly, theists can argue that the plan of their deity(ies) is such that our existence be a consequence of the actual laws and initial conditions.

Arguments Against Metaphysical Naturalism

Metaphysical naturalism has been criticized by many, particularly by specific religious communities. Some arguments against metaphysical naturalism are surveyed below.

Evolutionary Argument Against Naturalism

Alvin Plantinga, a contemporary philosopher of epistemology at Notre Dame, has argued that anyone who holds to the truth of both metaphysical naturalism and evolution is inherently irrational in doing so. His argument relies on establishing that the probability that unguided evolution would have produced reliable cognitive faculties is either low or inscrutable.

Since its inception, Plantinga's argument has been heavily criticized. Mental philosopher Daniel Dennett and historian Richard Carrier have attacked it on the grounds of misunderstanding natural selection. They argue that nature selects the genes of organisms that survive longer. Since pattern seeking in any multitude offer a substantial survival advantage, nature can effectively breed a cognitive apparatus for truth-finding. For example, primitive men that understood fertilizing plants and that flint makes fire would live longer because of their reasoning skills. This would allow them to pass reasoning abilities to their offspring. Out of this second generation, the offspring with the best rational faculties would live the longest because they discovered even more true patterns. Thus natural selection would continue to fine-tune man's truth seeking skills over time.

Argument From Design

Recently popular is the claim that certain structures in evolved organisms are too complex to have evolved by natural selection and can only be explained as the result of intelligent design. This argument suggests that certain biological instances (the favorite example being the eye) could not have occurred gradually, but must have come to be instantaneously. This is referred to as the argument from irreducible complexity.

A cosmologically-based argument, fine-tuning, states that the fundamental constants of physics and laws of nature appear so finely tuned to permit life that only the existence of a supernatural designer could explain them.

However, this has been asserted by many naturalists, like Victor Stenger, to be a god of the gaps argument because it creates a problem, says it is unanswerable, then fills in God as the solution. He also accuses fine-tuning as being a statistics fallacy, because it asserts after the fact what the chances were before the big bang. This fallacy makes it appear as though it was purposeful, because humans observe the after effect when it was just as likely to have any other combination that did not permit life.

It is also argued by Lawrence Krauss and Neil DeGrasse Tyson that the universe is not fine-tuned and is very unfriendly to life with only a small percentage of the universe being habitable. They argue life evolves to the conditions of the universe through natural selection, not the other way around.

A related approach which is consistent with existing science is that of physicist and philosopher Dennis Polis. He grants all of the science advanced by naturalists to support their case and shows it entails both the existence of God and a teleological view of nature. Naturalists in Polis' opinion simply project data into a solely mechanistic conceptual space, when the same data can be more adequately represented by a conceptual space in which mechanism and teleology are seen as complimentary.

Explanatory Gap

Since neuroscience has yet to explain the qualitative nature of conscious experience and its elements, commonly called qualia, some argue that naturalism is therefore refuted or should not be believed. Proponents of this argument suggest that naturalism's lack of a satisfying explanation on this matter is not a result of a simple lack of research (which would indicate that science may one day explain qualia), but that naturalism cannot explain qualia because no valid physical explanation exists in principle. One response by naturalists is to maintain that, while conscious experience exists, qualia do not. Yet another is to claim that this denial of a possible physical explanation has not been rationally demonstrated or factually grounded, but is an argument from personal incredulity and there is no reason to think that the mystery of consciousness is inherently unsolvable, that the apparent gulf between objectivity and subjectivity is unbridgeable, and that no sufficient reductionistic explanation can be offered.

A more decisive, semiotic argument is that naturalistic accounts of mind rely on the notion of instrumental signs, which are different in nature from the formal signs used in the mind, and furthermore, that instrumental signs require formal signs to operate as signs at all.

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