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Naturalism and Mind
Naturalism is a worldview based on experience, reason, and science. Non-naturalisms can attempt to refute naturalism by arguing that naturalism cannot fully account for experience and mind. Can all aspects of human experience find a coherent place within the naturalistic worldview? To at least establish the necessity for recognizing a non-natural reality, the non-naturalist only needs one counter-example to the naturalist's claim of coherence -- some single aspect of human experience which must be incompatible with nature. We will first survey arguments of the non-naturalist that conscious experiences and mental entities can never be accommodated within nature. Then we will look at disagreements between varieties of naturalisms about how best to deal with experience, consciousness, and the mind.
Which Experiences Challenge Naturalism? The incredible variety and complexity of human experience supplies endless targets for the non-naturalist. To simplify matters, let us consider just some "essential experiences". Naturalist and non-naturalist alike must admit that each essential experience is not only universally shared among humans, but also necessary for proper human functioning. What are such essential experiences? They are experiences of:
Notice that these essential experiences are here described as experiences of the world -- they must not be initially described as simply experiences, or as experiences of a mental world. After a non-naturalist has proven to her own satisfaction that naturalism cannot fully account for some essential experience, that experience gets quickly re-described as having a purely experiential/mental/spiritual nature, depending on the kind of non-naturalism preferred. But at the outset of the debate between naturalists and non-naturalists, these contested essential experiences must be assigned a neutral habitat for argument's sake. At this first stage, they are experiences of the world, in that common sense significance of the original empirical realism which we all assumed before any acquaintance with philosophy. A naturalist may be suspicious from the outset about even using the term "experience," since it is so laden with philosophical baggage that its use might give the non-naturalist an unfair advantage. However, what is here meant by an "experience of the world" is simply your conscious immersion in the world around you -- you are having experiences of the world simply by reading these words. Whether experiences of the world are really just mental experiences, or whether experience does not exist over and above the natural world, is for philosophical debate to decide. Before proceeding to non-naturalist arguments, you can read about "Consciousness", "Consciousness and Intentionality", and "Intentionality". The reason why these essential experiences are targeted by non-naturalists is because some naturalists, over the course of 400 years of modern experimental science, have announced that science's understanding of the world does not include them. This modern contest between naturalisms and non-naturalisms was prefigured by Hindu philosophies pondering the relationship between ultimate spiritual reality and the material things of the natural world, and then by Greek philosophies pondering the implications of metaphysical theories claiming that everything is made of one or more basic kinds of substances.
The Non-Naturalist's Preferred Mode of Argument Since the non-naturalist wants to prove naturalism false, the non-naturalist is most eager to raise disputes with naturalism over some essential experience which naturalism can never accept. Therefore the ideal sort of debate, from the non-naturalist's perspective, is to argue over some X where:
Most of the arguments given in support of non-naturalism have this basic structure. This argumentative structure erects some potential roadblocks for the non-naturalist, however. First, the non-naturalist must exhibit some widely experienceable X, and establish that knowledge of X is possible based on the experience of X. This is the "knowledge burden of proof" upon the non-naturalist. This is a high burden of proof. Merely experiencing X cannot help the non-naturalist engage the naturalist, since experiencing X is not, by itself, a very reliable guide to X's real existence. People constantly experience all sorts of things that turn out to be deceptive or illusory, and only tenuously connected with reality. The non-naturalist must defend a premise, like premise 2 above, to the effect that X can be known through experience. The non-naturalist may get aid from reason to meet this knowledge burden of proof, but not science, of course (this explains why non-naturalisms typically are foundationalisms, erecting deductive systems upon intuitions or revelations). Second, the non-naturalist must offer an non-naturalist theory which can account for the non-natural existence of X, to fulfill premise 4 above. This is the "theoretical burden of explanation" upon the non-naturalist. This second burden is necessary because it is not reasonable to abandon naturalism simply because people think that they know some X which naturalism rejects. After all, the claim that X is known could, on further reflection, turn out to be mistaken; and we should also keep in mind that naturalism might itself evolve with novel scientific knowledge so that naturalism no longer has to reject the existence of X. The non-naturalist may again get aid from reason (but not science!) to construct a theoretical explanation for knowledge of X, which strengthens his deductively rationalistic system. This is why naturalism views its perennial opponents as monstrous metaphysical rationalisms, and rarely confronts disorganized assemblies of intuitions/revelations. The "knowledge burden of proof" and "theoretical burden of explanation" upon the non-naturalist, however, are small in comparison with the third difficulty facing the non-naturalist: Must naturalism reject the existence of X? Some varieties of naturalism may reject X, while others may not. Non-naturalism can be reasonable only if all kinds of naturalism must forever reject the existence of some known X. Too many non-naturalists presumptuously declare victory after finding something experienced X which one variety, or only some varieties, of naturalism must reject. How many kinds of naturalism are there? In "Naturalism and Science" several significant varieties of naturalisms are distinguished. The non-naturalist must accurately accuse all naturalisms of rejecting the existence of X. This is the "accusation burden of proof" upon the non-naturalist. Let us see how the non-naturalist can attempt to discharge the three burdens of proof in the course of arguing against naturalism. The case of experiencing the colors of the world has been long debated.
Even if the non-naturalist can reasonably establish the truth of premise 2 (no easy task, which we will not pursue here), the non-naturalist has here failed to discharge the accusation burden of proof. Premise 3 is false, because not all naturalisms would declare that redness does not exist. Of the seven viable varieties of naturalism explained in "Naturalism and Science" only Eliminative Physicalism must reject the existence of colors. For example, Perspectival Pluralism has no difficulty accepting the existence of redness, and indeed regards the above argument as good evidence of its superiority over Eliminative Physicalism. In a similar fashion, such non-naturalist arguments fail to touch Perspectival Pluralism (or its cousin, Synoptic Pluralism) where qualities, meanings, values, and purposes are concerned, as well. Both Perspectival Pluralism and Synoptic Pluralism are designed to accommodate all these modes of experiencing the world. We can now grasp why the non-naturalist vastly prefers to assume that Eliminative Physicalism is the only variety of naturalism. During the second half of the twentieth century, Eliminative Physicalism and its close cousin Reductive Physicalism were the dominant varieties of naturalism. With so many of the perspectival and Synoptic naturalisms having fallen out of fashion (Peirce, Alexander, Dewey, Santayana, Whitehead, etc.), non-naturalisms turned their aim to easier targets. For the same reason, theological supernaturalisms have flourished recently (you can read about "Naturalism and Religion") simply by showing how their theories of souls and divinity rescue experience from elimination.
Non-Naturalism versus Reductive Physicalism When the non-naturalist turns to deal with Reductive Physicalism, the required argumentative strategy needs some fine-tuning. Here is a common argumentative strategy:
The crucial additional premise is premise 4. It is a version of a corollary, "if x and y are distinct then there is at least one property that x has and y does not," to Leibniz's "Identity of Indiscernables" principle. Few reductive physicalist have even considered rejecting premise 4, in light of its long useful service. More frequently, a reductivist will dispute premise 5 by claiming that the bare quality to an experience (the color of redness or the feeling of pain) is not essential to that experience. For example, the current popularity of functionalist accounts of mental states tempts the reductivist to say that anything non-functional, such as the pure qualitative "content" or "qualia" of a mental state, is simply inessential and hence irrelevant to the successful reduction. The non-naturalist can easily anticipate this question-begging tactic and erect the required defense of 5 by pointing out that the bare qualitative content, that redness or that pain, is precisely what naturalism fails to explain in experience -- that content/qualia is the experienced X in premise 1. Once reductive physicalism admits the irreducible existence of anything in experience, physicalism must be surrendered. The physicalist can at least claim as a parting shot that irreducible qualities must have no causal powers -- they somehow arise from the physical world but don't do anything, since only physical things can be causes. This is the position of "Epiphenomenalism". Epiphenomenalism is the simplest form of Synoptic Pluralism. Perspectival Pluralism cannot rest content with epiphenomenalism because its concern for coordinating perspectives demands greater participation from experience, such as postulating mental causation, or higher integration of experience with the rest of nature, such as postulating that experience is a natural system itself. Alternatively, some reductive physicalists place their hopes in causation, arguing as follows: (1) All mental states have causal relations with other mental or physical things; (2) If a mental state has causal relations then that mental state must actually be a physical state with physical causal relations; (3) All aspects of a mental state must make a contribution to that state's causal role; so therefore (C) All aspects of a mental state (including all qualitative aspects) are in some sense physical. Establishing the truth of premise 3 in a non-question-begging way cannot be easy, however. How could its truth be experimentally decided? Reductive physicalists disagree among themselves whether premise 3 is correct. The casual argument is considered further in a later section about disagreements between naturalisms.
Another Non-Naturalist Argument Against Physicalisms One of the most discussed arguments against both Eliminative Physicalism and Reductive Physicalism is the "knowledge argument". Its basic argumentative structure is as follows:
This argument is only effective against physicalisms, since other varieties of naturalism deny that all knowledge is provided by physics. The success of this argument against physicalisms depends on the interpretation of premises 2, 3 and 5. The non-naturalist must defend premise 2 against the notion that ordinary experiences of things do not yield anything deserving the name of knowledge. For example, a physicalist might complain that experiencing X only yields an ability to recognize X, to recall X's name, etc. However, this tactic violates common sense usage of "knowledge", since those abilities are a large part of what we mean when we say that someone knows features of things. Surely I know what the back of my hand looks like. Regarding premise 3, a physicalist might say that knowing "what X is like" is only an inferior kind of knowledge. This requires a non-naturalist response defending experiential knowledge as equal or superior in standing to the knowledge of physics. This defense might point out that scientific knowledge itself rests heavily on simple experiential knowledge like "this litmus paper just turned red." Can superior knowledge be justified by inferior knowledge? Given the difficulties of dismissing or diminishing experiential knowledge, most physicalists focus on whether premise 5 is correct. Lacking the ability to put a highly intelligent physics expert (call her "Mary") to any sort of test, philosophers are left with intuitions. The non-physicalist cannot imagine how even a divine intelligence could know what redness or pain is like without directly experiencing it (this intuition has troubled some theologians whose perfect God might not know what it is like to be human). The physicalist might not be able to imagine exactly how Mary could have the acumen to know redness or pain by inference solely from physical knowledge either, but the physicalist could retort that our inability to understand this acumen cannot disprove its possibility. This standoff comes down to one's strongest intuitions. Would Mary, a super-intelligent knower of perfect physics, who had never yet seen any colors, really fall for the "the blue banana trick": When Mary is permitted to see anything colored for the first time and is shown a blue banana, would she immediately know just from looking that it has the wrong color? Most people's gut intuition says "No." A physicalist could argue that Mary would immediately know that her visual state is an experience of "blue" and she would merely reconceptualize or redescribe that mental state in the light of the new experience without having to add any new knowledge. However, this argument fails since Mary wouldn't have to redescribe her visual state if she already knew the concept "experience of blue," so there still is a kind of genuine knowledge about a visual fact which was missing from her prior physical knowledge. You can read more about this argument at "Qualia: The Knowledge Argument".
Non-Naturalism versus all Naturalisms on Free Will We have seen how Perspectival Pluralism and Synoptic Pluralism elude the above non-naturalist arguments. The non-naturalist can proceed to argue against each variety separately. Against Perspectival Pluralism, the non-naturalist would have to demonstrate that some aspect of experience will always refuse to coordinate in a system with the rest of nature, by finding some kind of experience that is so different and aloof from everything else in the world that coordination seems impossible (mystical non-naturalisms make this attempt, for example). This tactic will not work against Synoptic Pluralism, which is well-prepared for recalcitrant aspects of experience. Here the non-naturalist can only complain that synopticism is tantamount to a confession that many things seem quite unnatural and only the synopticist's ontological stubbornness forges any sort of unity out of such diversity. Of course, the synopticist can reply that the non-naturalist is also under a similar obligation to make sense of scientific knowledge and the natural things of the world, and the synopticist predicts that fulfilling that obligation will draw the non-naturalist back to Synoptic Pluralism. The non-naturalist can avoid arguing against each variety of naturalism by finding some incorrect principle to which all naturalisms must adhere. What false principle can be located? Well, naturalism gives great credence to modern science. Could some basic principle of modern science actually be mistaken? Here is a specific example of how a non-naturalist can try to argue against all naturalisms:
We will not pause to explore the provisional definition of "free will control", beyond noting that it is also called "contra-causal free will" because if it exists, then a freely willed choice could occur "contra all prior causes" -- such a choice would not be controlled by any prior causes. Nor will we be able to explore whether premise 2 is really true -- you can read about "Free Will" and "Determinism" and "Nondeterministic Theories of Free Will". The crucial premise in this argument is premise 3, because naturalists (and scientists) have long been in disagreement over its truth (for example, does quantum mechanics imply strict determinism?). And we will not settle that disagreement here, either. Interestingly, some philosophers have concluded that free will control is impossible either way -- even if premise 3 is false, free will control cannot be real. Le us call this dilemma the "freedom vs. control paradox". Consider that if strict determinism is false, then some events happen on a purely random and chaotic basis -- such events are impossible to predict and impossible to control (if you could control such an event, then it would be pre-determined largely by what you do right up that event). Let R be some random unpredictable event -- can you have free will control over R? Put another way, consider that if you did do R, maybe you could claim that you "chose" R to happen (like you thought about R happening right before R happened), but could you also claim that you controlled R happening, when R is so undetermined that not-R could have just as well happened instead? No, you could not claim control over R. The notion of "free will control" in premise 1 of this argument contains a paradox: to gain perfect freedom from prior causes, one must surrender control. Maximizing freedom eliminates control -- but is the reverse necessarily true? Does maximizing control require eliminating freedom? Some naturalists do accept this corollary, and their "hard determinism" leads them to a complete rejection of the notion of freedom. Other naturalists offer a "soft determinism" or "Compatibilism" version of free will control which does not suffer from the problems of contra-causal free will. On this rival view of free will control, people do experience the feeling of freely willed choices. However, what people are feeling is not any sort of complete independence from all prior causes, but rather the feeling of their own internal causes leading towards a chosen action (while also feeling resistance from external forces). After all, unless people had their own internal powers of causation (arising ultimately from the energies of bodily metabolic chemistry), they would not be able to do anything or choose to do anything. Consider the "freedom vs. control paradox" again -- we concluded that have control over an action requires tight causal connections between prior causes and the present action to be performed. Even if strict determinism is correct, a person naturally feels free will control because the process of a decision is the process of internal causes (mostly in the nervous system) that culminate in the person's chosen action. It would be silly to demand freedom, at the moment of final choice and action, from the process of deliberating over a decision that led up to that choice. We should not want freedom from our internal deliberation, but rather freedom from outside forces of interference with either the process of deliberation or the culminating chosen action. For the compatibilist, the freedom that people really want is the freedom of control (not freedom from all control) over our actions despite outside forces in the environment. This notion of "freedom of control" resolves the "freedom vs. control paradox". We can increase our freedom as we increase our control. We well know the sharp distinction between the internal causes that compose our decision processes, and the outside causal forces that disrupt or obstruct our desired control over our actions. We desire greater freedom over our actions, and so we want fewer outside obstacles so that we can have greater control. The "freedom of control" exists regardless of whether strict determinism is true, or whether nature is only partly deterministic. Even if the past only partly dictates the present, people are not thereby deprived of control over their choices. The compatibilist regards choosing as a deliberative process over time -- not as an instantaneous event. Even if there happen to be some small irregularities and departures from strict determinism throughout a process of choosing, that process will hardly be completely random or entirely unpredictable. We can control a process even if the outcome is not completely predictable (and indeed we experience our own deliberative processes as unpredictable, in the sense that we don't know what we will decide until the process is complete -- if we already knew, we wouldn't deliberate over the choice). How does the compatibilist naturalist explain moral agency in a way that is consistent with science? Here we repeat points also made on the "Naturalism and Morality" page. A free will sufficient for moral agency only requires that a person have both (a) partial internal control over its own current habits, and (b) partial internal control over the deliberate modification of its habits. This partial control is not any sort of contra-causal free will, but rather recognizes humans as energetic causes in their own right, alongside environing causes. Where people have both (a) and (b) we rightly hold them morally responsible and use reward and punishment accordingly [reasonable rewards and punishments would be designed to increase (a) and (b) over time]. Not all naturalists believe that people have (a) partial control over current habits, and (b) partial control over the deliberate modification of habits. Some naturalists over-emphasize "hard determinism" by tracing everything a person is capable of doing back through causal processes that eventually come from the outside environment and pre-date that person's existence, and then happily deny that humans ever really control any of their conduct. The false premise to both sides, common to defenders of contra-causal free will and defenders of hard determinism, is the notion that "unless a person can have control over ultimate causes for their conduct, that human lacks full responsibility". Why is this premise false? When a person does have free will over a choice C, that is not because that person could also have not done C given all the same conditions at that moment (internal plus external causal processes), but rather because that person could also have not done C given all the same external conditions at that moment. If, in a given situation, a person could do C and also not do C, given all the same external conditions at that moment, this explains why this person rightly feels that their own internal decision process controls the outcome, and also explains how culture can assign responsibility for decisions over which we have control. We hold a person responsible for an action because we conclude after inquiry that this action probably wouldn't have occurred given only all the same external casual conditions at the time of the action -- isolating by subtraction this person as the "cause" of that action. The fact that this person could not possibly have performed that action without the cooperation of many external causal processes in the PAST is quite irrelevant to assigning responsibility (but quite relevant to the different question of whether we additionally will praise or blame this person, reward or punish this person, for this action). No naturalist should accept any notion of "contra-causal free will". The hard determinist, usually a physicalist, will prefer to eliminate freedom or reduce the "illusion" of free will to physical events. The compatibilist, who may be among the ranks of any of the varieties of naturalism, analyzes the undoubted feeling of free will control as the "freedom of control" that naturally arises when a person experiences the process of deliberation and culminating chosen action as a connected series of internal causes which successfully overcome outside obstructing causal forces. In summary, non-naturalists have not succeeded in establishing their view that some non-natural reality is required for understanding experience. In fact, their arguments only succeed in highlighting difficulties with eliminativism and reductivism, and the potential superiority of pluralistic and Synoptic varieties of naturalism. We now turn to these disputes among naturalists.
What do the Varieties of Naturalism say about the Mind? Modern naturalism, which we may date from the late 1800s, has competed against its rivals at four levels: conceptual, epistemological, ontological, and metaphysical. Earlier naturalisms, for the most part atomist materialisms, could point to few scientific advancements and had to fight powerful theological forces just to keep scientific research respectable. By the 1880s, physics, chemistry, geology, and astronomy were well established, and biology was becoming Darwinian. Very few philosophers defended naturalism at that time, however. Phenomenalists, personal idealists, Cartesian dualists, neo-Kantian transcendentalists, and neo-Hegelian objective idealists all agreed that scientific knowledge is at best an imperfect kind of knowledge that fails to grasp much of reality. Their primary arguments against naturalism, still robust today, can be gathered together into four kinds: conceptual, epistemological, ontological, and metaphysical.
In response, naturalists must raise conceptual, epistemological, ontological, and metaphysical defenses of science and the scientific worldview. Different kinds of naturalists prioritized distinct fronts, giving rise to four distinct naturalistic strategies:
There are ways to pursue these naturalistic strategies on all three fronts in a coherent fashion, so that none of the three is over-emphasized to the diminishment of the others. The seven viable varieties of naturalism, as explained in "Naturalism and Science", take rival positions on the nature of experience, consciousness, and mind. For example, Eliminative Physicalism uses the combination of 1a, 2a, 3a, 4a and Reductive Physicalism uses the combination of 1b, 2a, 3a, 4a, while Perspectival Pluralism uses the combination of 1b, 2b, 3b, 4b and Synoptic Pluralism uses 1c, 2c, 3c, 4c. The most significant disputes within naturalism are between these four varieties of naturalism -- the victor of that intense competition will be in a good position to permanently sideline any non-naturalism. However, in recent decades the most heated disputes within naturalism are between Reductive Physicalism and near-cousins in the middle range between Reductive Physicalism and Perspectival Pluralism. Let's first get reacquainted with each variety, briefly describing their overall approach, and their divergences from each other. Eliminative Physicalism: the only realities are those that number among those things (or among their properties) which are described by physics' best theories. This eliminativist does not attempt to explain any experiential, conscious, or mental phenomena, because these things do not exist in the first place. Unlike the reductivist, who may believe in the existence of some of those phenomena because they "really are" physical in nature, the eliminativist is not interested in reducing such mythical or delusional entities. For example, the reductivist may be interested in reducing beliefs to brain states, or reducing colors to radiation frequencies. By contrast, the eliminativist would only be interested in some new physical theory about the functioning of the nervous system which eliminates any need to think that "beliefs" ever really existed, and would declare that anyone who thinks that they see colors is just suffering from a delusion. Since many experiences are likely not delusional (we are pretty sure that we have beliefs and see colors), the typical self-proclaimed eliminativist is actually in practice a reductivist concerning most things. For example, the eliminativist thinks that chairs exist, even though physics doesn't mention chairs as fundamental entities, because she holds the reductivist view that chairs are noting but collections of atoms. Regarding such common-sensical things as beliefs and colors, physicalists are more inclined to be reductivists, since accusing most of humanity of a massive collective delusion seems presumptuous. More importantly, the elimination of such things as experiences, meanings, beliefs, and reasons would undercut the grounds for justifiably accepting eliminative physicalism -- we need to experience the world to learn about it, we need meaningful concepts to describe our learning, we beliefs about the world to accept physics, and we need reasons to trust only physics to become eliminative physicalists. Eliminativists, such as radical behaviorists (see "Behaviorism") and some functionalists (see "Functionalism") look forward to the replacement of "Folk Psychology". Still, talk of experiences, meanings, beliefs, and reasons has a permanent pragmatic utility. That utility will transfer to any linguistic terms that function similarly. Even if people stop talking about having "beliefs", people will still use sentences which express judgments, and other people will talk about my own propensity to express certain judgments. Once an eliminativist admits the ineliminable practical value of such elements of folk psychology and portions of other theories of nature, then reductivism appears to be the better alternative than a radical jump over to pluralism. Reductive Physicalism: the only realities are those of physics' best theories, plus those additional things which can be theoretically reduced to them. Reductive Physicalism resists collapsing into eliminative physicalism by permitting the existence of some things that can have their own properties, behaviors, and laws that physics itself does not investigate. For example, chemistry's knowledge of molecules can be legitimate, so long as chemistry accepts that its entities and laws must be in principle reducible to physics' entities and laws, even if it may be difficult or seem impossible for scientists to figure out all those reductions. The reductivist thinks that reductive physicalism has several advantages over eliminativism: (1) reductivism can still accept the existence of (properly reduced) experiential/mental things with obvious existence or ineliminable practical value; (2) reductivism can endorse many common sense or folk psychological explanations of human conduct (such as "My thirst caused me to want to drink the water"); (3) reductivism can happily eliminate from existence anything irreducible (so long as it is not too obvious or valuable); and (4) reductivism can happily encourage the other sciences besides physics to pursue knowledge so long as they submit to "reductionist universalism" -- all of reality ultimately consists solely of subatomic particles and that all events in the natural universe are ultimately dictated by the laws those subatomic particles obey. The reductivist worries greatly about Synoptic Pluralism, which regards experiential and mental entities as not only irreducible to physical entities, but as having their own somewhat independent properties and causal powers. Unimpressed by the pluralist's promise that mental entities are still connected and coordinated with physical entities, the reductivist views such liberation for the mind as the high road to synopticism (property dualism or epiphenomenalism, for example) which in turn could lead to naturalism's demise in ontological dualism. To forestall this slippery-slope disaster, the reductivist first demands physical supervenience, which is sometimes phrased as (a) every change in the mind (the mental event) must be correlated with a change in physical reality (the physical ground), or as (b) if two events share all of their physical/functional properties, they will share all of their mental properties (you can read about "Supervenience"). Physical supervenience is, by itself, just a placeholder for the physicalist's next demand that anything experiential or mental must be ontologically and metaphysically dependent on some physical ground. That means that the reductivist can never be content with mere supervenience. After all, without further argument physical supervenience probably only entails property dualism, which can then lead to epiphenomenalism or ontological dualism. Furthermore, some dualists or idealists can happily accept physical supervenience and match it by demanding mental supervenience: every thing in physical reality must be correlated with some thing in mental reality. The reductivist must additionally argue that physical supervenience supports the view that nothing experiential or mental can have any property or capacity or causal efficacy independent from some physical ground. By elucidating such utter ontological and efficacious dependency, the physicalist is then in a good position to claim that the mental has been reduced to the physical (and what proves resistant to reduction must be eliminated). Reductivism must enforce reductionist universalism on any science that deals with experiential/mental phenomena, and it must establish the complete ontological and efficacious dependency of all experiential/mental phenomena. Failure on the first task leads to Exclusivist Liberal Pluralism, while failure on the second task leads to Perspectival Pluralism (or worse -- sycretism and dualism!). Exclusivist Liberal Physicalism: reality consists of what can be explained by physics. This variety of naturalism does not adhere to the principle of reductionist universalism, keeping it distinct from its eliminativist and reductivist cousins. Exclusivist Liberal Physicalism does maintain an analogue of reductionist universalism, which can be called "explanatory universalism," which instead declares that only the things and laws theorized by physics may be referenced when explaining reality, so that explanations of things are given solely in terms of the things recognized by physics alone. Assuming that experiential and mental things can in principle be explained by physical processes, this variety of naturalism endorses physical supervenience and might halt at epiphenomenalism, since this variety of naturalism refuses to "reduce" the mind to physical matters. Perhaps epiphenomenalism can be suitably naturalized, but that doesn't end this variety's troubles. The primary difficulty that confronts Exclusivist Liberal Physicalism is causality: when physically explainable but irreducible things appear to have their own causal relationships (such as when my willing to raise my arm causes my arm to raise), what should be done about these suspicious causal relationships? Since there must be, for this variety of naturalism, a purely physical causal process causing my arm to go up, how can my arm going up also be caused by my willing it to go up? This sort of causal overdetermination is easily remedied by the reductivist or the eliminativist, who denies that my willing could have any distinct causal efficacy. Unless this causal overdetermination issue is somehow resolved, Exclusivist Liberal Physicalism is under great pressure to either collapse into Reductive Physicalism, or to go in the opposite direction and mutate towards Perspectival Pluralism. If Exclusivist Liberal Physicalism moves towards Perspectival Pluralism, it will pass through the half-way stages of either mere supervenience naturalism (everything mental is correlated with the physical) or anomalous monism (all reality is physical, but reductions are not possible -- you can read about "Anomalous Monism"). These two stages are not viable naturalisms because they attempt to combine incompatible elements: the pleasant dream that physicalism has been established paired together with the harsh awakening that physicalism cannot be established. When supervenience is recognized as only a presumption lingering from the expired dream of reductionism, and when the anomalous aloofness of the sciences' theories is judged as the death sentence for the physicalism of the Unity of Science, then the options of Exclusivist Liberal Pluralism, and even Perspectival Pluralism, seem more attractive. Exclusivist Liberal Scientism: reality consists only of those things that are explainable by the physical sciences. Privileging the physical sciences makes sense in the wake of reductionism's privileging of physics (leading this variety to collapse into Reductive Physicalism), but the social sciences, especially psychology, understandably protest. Why must psychology and sociology fail to gain genuine scientific knowledge of experience and mind? When Exclusivist Liberal Scientism dismisses psychological or sociological accounts of mind, it had better generate satisfactory explanations using only the physical sciences without recourse to reduction. Like Exclusivist Liberal Physicalism, this variety must resolve the issue of causal overdetermination as well without recourse to reduction. If the temptation of prioritizing physicalist explanations and appealing to reductions proves irresistible, this variety collapses into Reductive Physicalism. On the other hand, if psychology and sociology prove their worth according to scientific method, Exclusivist Liberal Pluralism is far more attractive. Exclusivist Liberal Pluralism: reality consists of what can be explained by the sciences. Its pluralistic approach encourages all of the sciences to draw their own conclusions about experience, consciousness, and the mind. This liberality encourages such a diversity of conclusions about reality, and such a multiplicity of entities for theorizing, that incoherence among them will inevitably result. The only way to manage this diversity is to assign each science its own task of exploring a "level" or "aspect" of reality, so that clashing scientific theories are kept apart. For example, psychology studies mental entities and their relation to conduct, while neurophysiology studies neural processes and their relation to conduct, and Exclusivist Liberal Pluralism does not worry about how these entities and laws relate to each other, or whether they might depend on each other. For example, the pluralistic toleration for such things as folk psychology and mental causation need not burden any other science with accounting for the existence of beliefs or volitions. This liberality pulls exclusivism towards perspectivism -- the view that each science's knowledge is only one valid but limited perspective// on reality, and no science has a monopoly or even a priority on what really exists. Although freed entirely from any reductive drives, Exclusivist Liberal Pluralism must show how all experiences and mental events are in principle explainable by the sciences. Any experiences not satisfactorily explained will pressure this naturalism to mutate into Perspectival Pluralism. Perspectival Pluralism: experience and scientific knowledge presents multiple perspectives upon reality. Perspectival Pluralism requires some sort of naturalistic metaphysics -- a metaphysical account of reality that incorporates all experience and knowledge for constructing a coherent understanding of one single natural reality having multiple but coordinated perspectives. The inspiration (or desperation?) to resort to a metaphysical naturalistic system derives from two considerations: (1) the inability of the sciences to explain, on its own terms, much of experience and the mind; and (2) the ability of the sciences to cohere with, and frequently illuminate, much of experience and the mind. For Perspectival Pluralism, science cannot absorb experience or the mind, yet science does help us comprehend experience and the mind. Our mental lives are correlated to some degree with nervous processes, scientific knowledge grows from our careful observations of the world, and our experiences of the world can be usefully coordinated with scientific knowledge. Appreciation for the many vital and practical relationships and interpenetrations among experiences and scientific knowledge inspires the Perspectival Pluralist to infer that there is only one natural world that experience and science both reveal. To justify this confidence in one natural reality, the Perspectival Pluralist must develop a metaphysical system to show how all experience and all scientific knowledge can be coordinated together. Any irreconcilable contradiction between some aspect of experience "E" and some part of scientific knowledge "K", a contradiction so severe that it is impossible to see how E and K could both be about the same natural reality, will doom Perspectival Pluralism. Making this task easier is the view held by Perspectival Pluralism (but not its cousin, Synoptic Pluralism) that experience is not itself a kind of knowledge that could challenge scientific knowledge. Synoptic Pluralism is designed to handle conflicts between experiential knowledge and scientific knowledge by assigning what each knows to separate modes of reality. The Perspectival Pluralist worries that such an accommodating synopticism is tantamount to a resignation to ontological dualism. Synoptic Pluralism: reality has a variety of aspects or modes as revealed by the many sciences, and also has aspects or modes revealed by experience that the sciences are incompetent to describe or explain. The Synoptic Pluralist is not only convinced of the failure of reductionism, but also persuaded that perspectivism's effort to coordinate experience with scientific knowledge is excessively optimistic. There are too many irreconcilable incompatibilities between much of experience/mind and scientific knowledge -- they cannot be coordinated into a system of coherent perspectives. Experience and the mind is a source of genuine knowledge, according to synopticism, which deserves equal or higher status than scientific knowledge. Therefore, the best way to deal with the world as mentally known and the world as scientifically known is to treat these two worlds as categorically distinct modes of one underlying reality. The simplest forms of Synoptic Pluralism include Dual Aspect Monism (the sciences deal only with reality's physical aspect while the mind only deals with reality's mental aspect), and Panpsychism (the sciences accurately but only partially describe all realities, because the sciences cannot capture the sentient or feeling aspect of these realities). More complex types of Synoptic Pluralism postulate multiple modes of reality, as many needed to keep incompatible portions of mind and of science apart. Synoptic Pluralism requires some sort of naturalistic metaphysics -- a metaphysical account of reality that constructs a coherent understanding of one single natural reality having multiple modes and experienced and known in multiple ways. Although coordinating and rendering compatible such diversity is difficult, synopticism can more easily segregate incompatible aspects into distinct modes of reality that need not intersect. Synoptic Pluralism is regarded by ontological dualists as the last halting place before confessing the existence of two or more ontologically distinct realities. Synopticists disagree among themselves about how to prevent ontological dualism.
Arguments among Varieties of Naturalism Since the agenda of reductive physicalism has driven naturalism for over fifty years, we may usefully survey the main arguments between varieties of naturalism as a series of disputes that occur as philosophers are tempted to move farther and farther away from reductive physicalism and then its near cousins. Reductive physicalism's agenda regarding experience and the mind has been to permanently banish all phenomenalisms, dualisms, and idealisms from philosophy, forever securing the victory of naturalism. Eliminativism made the same effort to save naturalism in a more radical way, utilizing ideas from positivism, pragmatism, verificationism, and behaviorism for strategizing how to make it impossible to even meaningfully describe anything non-physical. Eliminativism as a general strategy developed in the 20th century as a counter-reaction to non-naturalisms arguing that naturalistic concepts and language must be entirely reducible to concepts about experience and mind, lest they be quite meaningless. Phenomenalisms and idealisms were especially anxious to argue that all concept's meanings are inextricably rooted in mental experience and would lose their meaning entirely if that mental home were abandoned. Could concepts about non-mental entities have genuine meaning? Extending the notion that the meaning of concepts lie in their application, new empirical naturalisms took a "linguistic turn" in the first half of the 20th century. The natural home of concepts is objective language, and these naturalisms hence declared that it was idealism's restriction of concepts to the mental world that made them meaningless. By demanding that concepts have their home in public language, naturalists supposed that they could radically undermine any alleged intrinsic connection between concepts and mind. For example, such a strategy designed by a eliminative physicalist typically holds that the phenomenal world must be semantically dependent: any meaningful statements about the phenomenal world must be in principle translatable into true statements of physics. We shall not here survey the many failed attempts to adequately translate undesirable mental concepts and language, such as those of "folk psychology," to purely naturalistic language. Foregoing eliminativism's strategy of scientifically replacing all folk theories about experiential and mental entities so that their existence can simply be denied, the reductivist instead wants to guarantee that these experiential and mental phenomena remain just that -- phenomena -- that are thoroughly accounted for by physicalism. In short, the phenomenal world (the collection of all non-physical phenomena) must be utterly dependent on the physical world (the world as known by perfected physics). This utter dependence for the reductive physicalist has four interrelated dimensions:
The "final victory" strategy of reductive physicalism is to sufficiently justify all four dimensions of mental dependence. If successful, this strategy eliminates any way for a non-naturalism to reasonably claim that something non-natural could possibly have any sort of genuine reality beyond the physical. This strategy promises the additional benefit of respecting the phenomenology of experience/mentality, to avoid accusing humanity of "massive error" -- mass delusions and hallucinations. We discuss the overall prospects for Reductive Physicalism in "Naturalism and Science". Our survey here, concerning successive departures away from Reductive Physicalism, and the resulting arguments between varieties of naturalism over the mind, proceeds by considering philosophical worries about the four proposed dimensions of mental dependence. Each stage of departure away from Reductive Physicalism retains some hope for one or more of the dependencies, and arouses additional sympathy by claiming that any further departure is a dangerous advance towards non-physicalism. Philosophical naturalists disagree over whether there are any logical implications (the truth of one necessitates the truth of another) or epistemic justifications (justifying the likelihood of one helps to justify the likelihood of another) holding between any of the dependencies. Semantics Let's begin with the first dimension, that of semantic independence. Semantic independence asserts that there can be meaningful concepts, meaningful propositions, and meaningful descriptions, of phenomenal entities. Phenomenal and mentalistic terms are needed for describing and evaluating the world, and such terms cannot be reduced to, or replaced by, purely physical terms without losing some needed meaning. One prominent example of such irreducibility is the multiple realizability of a mental entity. Multiple realizability can happen in many fields of discourse, especially where biological, psychological, or social entities are concerned. Can the natural entity "wing" be reducibly identified with any specific type of physical entity? Any number of specific kinds of physical structures can be wings -- "wing" is multiply realizable by an indefinite number of physical structures -- so "wing" cannot be translated into any finite set of types of physical structures. This "loss in translation" is due to the functional nature of "wing" -- a wing is largely defined by how it functions, not by what is made of. Functionality and normativity is even more essential to phenomenal and psychological entities -- might "pain" be multiply realizable by an number of different nervous structures or patterns of nervous activity? If a reductivist aims to identify a mental type of entity with some type of physical entity, any functional or normative character of that mental entity is lost with that identification. The eliminativist's aim of dispensing with functional and normative terms might not be frustrated by multiple realizability, however -- you can read more about "Multiple Realizability". Semantic independence, in the meantime, can seem to be a convenient compromise for a physicalist who is more concerned about epistemic, ontological, or metaphysical issues. Semantic independence nevertheless makes a problematic beginning for Reductive Physicalism, and these problems can arouse renewed fondness for eliminativism in some reductivists. Why should conceiving or describing phenomenal entities as phenomenal be a problem? First, because we become acquainted with most phenomenal entities under their phenomenal concepts (we learn about pain as the phenomena of painfulness, and not as the firing of a certain series of neurons), and second because we can learn to identify pains as neuron firings only through scientific research. There appears to be no analytic relationship, at least prior to the conclusions of scientific research, between a conception of a phenomenal entity and a conception of a physical entity or function. "Redness" in ordinary language does not have any analytic or a priori relationship with "firings of optical cortex C-fibers" (e.g.) and meaningful phenomenal language needs no such relationships. If we must identify a color by observing it, and if that color (say, of redness) is an essential property of that phenomenal observation state (how could it be a contingent property -- as if we might discover that the redness didn't have to be a property of seeing red?), then how can it also be identified with any physical state or function? Here we are confronted with a version of the non-naturalist's "knowledge argument," examined in a section above. Kripke's formula, "If A is identical with B, then necessarily A is identical with B", tells us that there cannot be any merely contingent identities. The danger to reductivism here is that our ability to accurately conceptually identify a phenomenal entity by its essential property appears to either logically or at least epistemologically justify our ability to independently know that phenomenal entity as it is in itself, quite apart from any knowledge of whether it also really is a physical entity. If we do have this knowledge, then a phenomenal entity cannot ever be identified with any physical entity/function, since we know that the phenomenal entity possesses an essential property that the purported physical entity/function lacks. Summarizing, excessive semantic independence might establish epistemic independence and metaphysical independence, to the reductivist's great dismay. The strong temptation of the reductivist is to reply to this "semantic independence" problem by saying that once a scientific theory justifiably identifies a phenomenal entity with a physical entity, an analytic or a priori relationship is established between them, effectively eliminating anyone's ability to directly and immediately conceive of a phenomenal entity as just a phenomenal entity, and thereby preventing any independent knowledge of that entity. This is not ontological elimination, attempted by Eliminative Physicalism, but rather conceptual elimination. For example, now that science knows that water is H2O, no one can correctly conceive of, or successfully refer to, water without conceiving or referring to H2O -- and now that science knows that table salt is NaCl, no one can correctly conceive of, or successfully refer to, table salt without conceiving or referring to NaCl. If this reply works, then any connection between semantic independence and epistemic dependence is severed. However, this strategy is implausible with water and table salt and highly doubtful with colors or pains. It is not even necessary to clam that it is impossible to incorrectly conceive of, or refer to, a phenomenal pain or a phenomenal color (this tactic introduces dubious and possibly question-begging epistemic assumptions). Rather, this reductivist/eliminativist strategy is just a return to the "massive error" problem -- how could the rest of humanity suddenly fail to be conceiving of, or referring to, water simply because scientists learn that pure water is H2O? Perhaps the physicalist should accept massive error. Is massive error about phenomenal matters any more surprising or disturbing than the massive error that common sense commits when people casually talk about their "arthritis" or their "heartburn"? Of course, we expect scientific knowledge to improve common-sensical knowledge. But the "conceptual elimination" of matters at the core of ordinary language and folk psychology is an entirely different matter. Since successful conceptualization and reference cannot depend on whether someone else knows phenomenal-physical identities (one minute Harriet successfully refers to water but fails the next minute, just after the initial discovery that water is H2O?), everyone must have suffered from massive error about water (and pain and color, etc) and many still do. Going further, since future scientific knowledge will replace not only current ordinary language but much of current scientific language as well, the conceptual eliminativist must admit that scientists themselves now suffer from massive error and complete failure to refer to reality. Thorough-going skepticism now looms -- skepticism about the ability to conceive of and refer to phenomenal entities has spread throughout our ability to conceive or refer to reality at all. Could scientific knowledge ever build upon such a false empirical foundation? Is this drastic skepticism really necessary? If the reductivist tries to claim that no deep skepticism is necessary, since languages have partial conceptual and referential success (hopefully in increasing amounts as science progresses), such a generous offer only encourages perspectivism. Furthermore, the reductivist earnestly desires physical theorizing to identify a phenomenal entity with a physical entity/function, but even if such scientific knowledge could be achieved, how could that knowledge in turn establish an analytic or a priori relationship between them? The naturalist should not expect scientific theorizing to establish any analytic or a priori truths -- scientific theorizing may use such truths, and perhaps revise them in the course of improving theories, but could science establish them as conclusions? These difficulties give further encouragement to the perspectivist, who can easily account for the distinct roles that ordinary language and physical theorizing play in accurately describing aspects of nature. The reductivist has only two options at this stage: (1) provide an explanation for how a phenomenal property (the feeling of pain, for example) could really turn out to be just a contingent property of its own phenomenal entity (being in pain); or (2) provide an explanation of how massive conceptual and referential error need not escalate into the sort of deep skepticism that undermines science itself. Option 2 is easier, but avoiding perspectivism will require the re-introduction of eliminativist themes. Essentially, the half-way point between reductionism and eliminativism regarding semantics would be the position that phenomenal language is just that -- an apparent language for talking about apparent things -- which uses apparent concepts. In other words, the concepts applied to phenomenal things (a) immediately and accurately grasp the phenomenal appearance, and (b) inaccurately grasp that phenomenal appearance's true (physical) nature. This understanding of phenomenal concepts (offered, for example, by some "new wave materialists") prevents phenomenal semantics from grasping reality, and so severs the putative link between semantic independence and epistemological/metaphysical dependence. However, phenomenal semantics is just a polite way of re-admitting massive error regarding the empirical world, and still must confront the task of protecting scientific observation of the empirical world from this massive error problem. Epistemology According to reductive physicalism, the phenomenal world must be epistemically dependent: the knowledge of reality provided by perfected physics is complete. There can be no knowledge of the phenomenal world outside of the knowledge provided by perfected physics. The severe dilemma that immediately confronts this view can be raised by asking whether (1) phenomenal experiences are sufficient by themselves to generate and justify knowledge, or (2) they are not sufficient to generate and justify knowledge. Obviously, the reductive physicalist must take the second horn of the dilemma. However, if phenomenal experiences, qua phenomena, are simply had, noticed, and described, but not known, how could the reductivist know how to successfully reduce them to physical entities or functions? All of the instances of successful reductions, to which the reductivist so proudly points, are instances in which one objectively known object or natural law is reduced to another objectively known object or natural law. The scientifically measured temperature of some substance is reduced to the average kinetic energy of that substance's molecules, for example. Successful reductions are relations established between theories of scientific fields. How would a reductivist reasonably explain how science could ever reduce a scientifically unknowable entity to a scientifically known entity? Of course, any overconfident reductivist could claim that science would learn how to accomplish such a feat -- but it is actually impossible in principle. What this overconfident reductivist is actually claiming is that first science would figure out how to know the phenomenal entity in question, and then learn how to reduce it. But the first step in this simple-sounding procedure is already ruled out when the reductivist chose the second horn of the dilemma -- if phenomena are scientifically known, they are no longer phenomenal and no longer need reducing, and if phenomena stay phenomena, they can never be reduced. There is no non-question-begging way around this reductivist dilemma. This dilemma is only a dilemma for the reductivist. The eliminativist would not take the phenomenal realm seriously enough to fall into this dilemma. The perspectivist, on the other hand, by agreeing that most phenomenal experiences are only had and described but not known, understands their natural existence as quite natural and only needing coordination with scientific knowledge in a coherent system of perspectives. The debate between the reductivist and the several non-reductive varieties of naturalism thus arrives at the ontological question of existence. Ontology According to reductive physicalism, the phenomenal world must be ontologically dependent: the dispositions/capacities/powers/laws/functionings which pertain to the entities and their properties as known by perfected physics are exhaustive. Nothing phenomenal is directly or indirectly responsible for doing anything over and above what the physical world does -- a phenomenal entity cannot make any difference to anything phenomenal or to anything else. What strategies are available to the reductivist for establishing utter ontological dependence? The following strategies are listed as sequenced stages designed for heightening the plausibility of complete ontological dependence. The ultimate aim of these stages is to demonstrate that any sort of reality that phenomenal entities possess must be only physical reality (or phenomenal entities may not even exist in any sense at all, reminds the eliminativist). The notion of "supervenience" has become useful for the physicalist project. At the start of the article "Supervenience" we read:
This concept of supervenience includes a "directionality" from the "A-realm" to the "B-realm" which makes supervenience relevant to any eventual assertion of the ontological dependence of the A-realm upon the B-realm. Let AsupB stand for the assertion of supervenience as defined above. Might BsupA also be the case? Perhaps, but when supervenience is applied in debates over reductionism, the assertion of AsupB is typically accompanied by a tacit denial of BsupA. In these debates, the A-realm would be the phenomenal/mental realm while the B-realm would be the physical realm. If both AsupB and BsupA are the case, then A and B are plausibly connected in some way, perhaps directly to each other, or to some third sort of entity more ontologically basic than either A or B. But that result does not lead towards reductionism, since the physical realm would not have ontological priority. The reductivist, wanting to avoid any implication towards a mutual ontological dependence between mind and nature, or between mind/nature and some third realm, therefore uses supervenience only to assert AsupB (mind supervenes on matter) while denying BsupA (matter supervenes on mind). The reductionist's use of supervenience to establish the ontological priority of the physical is highly problematic, and possibly even self-defeating. Interestingly, if the reductivist were to succeed in ontologically identifying some A with some B, not only must AsupB but also BsupA (by Leibniz's "Identity of Indiscernables" principle). In short, a genuine ontological identity necessarily entails two-way supervenience. This practically means that the reductivist's initial strategy of appealing to AsupB while denying BsupA is ultimately contradictory to the reductivist's final conclusion. The reductivist could reply that the initial denial of BsupA is only an argumentative supposition which can be modified by subsequent philosophical and scientific progress. This reply is inadequate, however, because the success of the reductivist's supervenience strategy crucially depends on the firm denial of BsupA until the final desired conclusion is reached. After all, the idealist is just as interested in establishing AsupB as BsupA, and can follow the reductivist's strategy right to the end -- when the reductivist announces the identity of the mental with the physical, the idealist will simply affirm BsupA as well as AsupB and announce the identity of the physical with the mental. Only a stalemate can result. Any successful supervenience strategy yields as much philosophical support for idealism as physicalism. The reductivist cannot reasonably establish the ontological priority of the physical by firmly denying BsupA from the beginning, only to conclude BsupA at the end. Since the mid-point of the 20th century, with no powerful idealist movement to confront, physicalists have not had to face up the contradictory nature of the supervenience strategy. But the contradiction looms nonetheless. Philosophers nowadays seem agreed that reduction requires supervenience; they don't seem to realize that any reductive identities require the two-way supervenience which the supervenience strategy must reject. Many non-reductivists, wanting to avoid both physicalism and idealism, find some of the weak forms of supervenience plausible while staunchly resisting the stronger forms. Non-reductivists who halt at some mid-way point of the supervenience stages are often labeled as "emergent naturalists." Their acceptance of some degree or kind of dependence of the mental on the physical licenses these philosophers to call themselves "naturalists," while their assertion that mental realities possess some kind of additional non-physical reality inspires them to describe such an extra reality as "emergent" from physical reality. You can read about "Emergent Properties". However, other kinds of non-reductivists must not be described as emergent naturalists, and emergent naturalism is not a basic variety of naturalism. Emergent naturalism in its simpler guise echoes the physicalist aim by prioritizing the physical -- the realm of emergent properties and entities depend on the realm of physical properties, but not necessarily the other way around. Many friends of emergence have noticed this lingering physicalist bias, and accordingly search for ways to make physical properties and entities dependent on the higher-level emergent realm as well. When a non-reductivist naturalist traces the mutual superveniences and dependencies between the mental and the physical, perspectival naturalism results. Yet perspectival naturalism is not emergent naturalism. Emergent naturalism has several forms which can be categorized with Exclusivist Liberal Pluralism or Perspectival Pluralism or Synoptic Pluralism, depending on the degree of autonomy which emergence may grant to the mental realm. The most basic form of supervenience used for the reductionist agenda is correlation supervenience, which begins to reign in autonomy for the mental.
The final aim of this supervenience strategy is to tightly connect every phenomenal/mental entity or process with some physical entity or process. The strongest connection would be causal supervenience, but reductivists are often wary of attributing causal efficacy to anything mental. Such wariness is probably counter-productive, since (1) common sense accepts mental efficacy as indispensable for describing and explaining much of human conduct, and (2) such reductivist defiance of common sense is actually the eliminativist's tactic of prejudging the empirical question of mind-matter identity. The wiser approach for the reductivist would be let empirical science decide whether instances of mental efficacy are dynamically or causally correlated with instances of physical efficacy. The reductivist agenda is enhanced by science's additional ability to discover purely physical explanations for why certain dynamic or causal superveniences hold. The progress of science towards executing the supervenience strategy is precisely the progress of the reductivist agenda. Of course, any empirical failure to find dynamic or causal supervenience for some portion of the mental realm, or failure to discover a purely physical explanation for such discovered superveniences, encourages Perspectival Pluralism, Synoptic Pluralism, or outright dualism. We have arrived at the metaphysical stage of debate between these naturalisms. Metaphysics The mounting evidence for widespread mind-matter correlation, both dynamic and causal, permits the reductivist to plausibly argue for ontological identity. The final goal of reductivism is metaphysical identity -- the only type of reality is physical reality. This identity can expressed using the notion of global supervenience: everything supervenes on the physical. In the jargon of possible worlds, this global supervenience can be roughly expressed as follows:
There are many complex problems involved with using supervenience to express the physicalist agenda -- you can read more about "Physicalism". Since many portions of the phenomenal/mental realm have so far resisted reduction by the supervenience strategy, various non-reductive naturalisms flourish. Furthermore, in light of the contradictory nature of the supervenience strategy, explained above, some non-reductive naturalisms can happily accept widespread superveniences of all types, only to conclude that the physical realm is as much dependent on the mental as the reverse. Both Perspectival Pluralism and Synoptic Pluralism, for example, would not automatically infer the ontological priority of the physical from dynamic or causal supervenience. Short of Perspectival Pluralism and Synoptic Pluralism, there are three interesting kinds of naturalisms that provide compromise options for the naturalist. Each of these compromises harbors a critical tension that may render it unworkable.
None of these three positions are as philosophically coherent or powerful as Reductive Physicalism and Perspectival Pluralism. Exclusivist Liberal Pluralism is a viable naturalism, but it is under great pressure to mutate towards either reductivism or perspectivism (see "Naturalism and Science" for more details why). Non-Reductive Physicalism and Emergent Supervenient Naturalism are not viable naturalisms because they try to hold together incompatible views concerning epistemology, ontology, and metaphysics.
copyright 2007 by John R. Shook |
