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Philosophical Materialism

Richard C. Vitzthum

[This essay is from a lecture given to the Atheist Students Association at the University of Maryland, College Park, on November 14, 1996, retrieved from

https://infidels.org/library/modern/richard_vitzthum/materialism.html]

Materialism is the oldest philosophical tradition in Western civilization. Originated by a series of pre-

Socratic Greek philosophers in the 6th and 5th centuries before the Christian era, it reached its full

classical form in the atomism of Democritus and Epicurus in the 4th century BCE. Epicurus argued

that ultimate reality consisted of invisible and indivisible bits of free-falling matter called atoms

randomly colliding in the void. It was on this atomic hypothesis that the Roman poet Lucretius

wrote the first masterpiece of materialist literature around 50 BCE, the 7400-line philosophical

poem De Rerum Natura, or, as it's usually translated, The Nature of Things.

Already in Lucretius' great poem we can see one of the hallmarks that distinguishes materialism

from every other comprehensive philosophy produced by European civilization before the 20th

century: its insistence on direct observation of nature and on explaining everything that happens in

the world in terms of the laws of nature. In other words, from the beginning materialists have always

based their theory on the best scientific evidence at hand, rather than on some putative "first

philosophy" waiting to be discovered through abstract philosophical reasoning.

The tendency is clear in the second masterpiece of materialist literature, Baron Paul d'Holbach's

anonymously published La Systeme de la Nature (The System of Nature), which appeared in France in

1770 and was promptly condemned by Louis 16th's government. This meant that the official state

hangman was authorized to ferret out every copy of the book and have it literally cut to pieces on a

beheading block. D'Holbach bases his mechanical determinism on Newtonian physics and Lockeian

psychology, arguing that every event in nature, including all human thought and moral action, is the

result of an inexorable chain of causation rooted in the flux of atomic motion. Like Lucretius, he

insists there is no reality other than matter moving in space, as Newton theorized in his laws of

motion and gravity. D'Holbach also attributes all thought to images impressed on the mind's tabula

rasa, or blank slate, in wholly mechanical fashion according to these same laws of motion, as Locke

had argued.

So too with the third pre-20th-century masterpiece of materialist literature, Ludwig Buechner's 1884

edition of Kraft und Stoff, translated Force and Matter, one of the most widely read and influential

German books of the 19th century. Himself trained as a scientist, Buechner, like Lucretius and

d'Holbach, saturated Force and Matter with the best science of his day, including cutting-edge theories

and discoveries in physics, chemistry, geology, and biology, which of course incorporated Darwin's

recently published theory of evolution.

Yet neither Lucretius, d'Holbach, nor Buechner claimed that materialist philosophy was an empirical

science. They all realized it rested on assumptions that were ultimately metascientific, though never

metaphysical in the Aristotelian sense. That is, the assumptions of materialism

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reached beyond empirical science, though never beyond physical reality. These metascientific

assumptions were, first of all, that material or natural reality formed an unbroken material

continuum that was eternal and infinite[1]. Nature had no beginning or end. It was an eternal, self-

generating and self-sustaining material fact without any sort of barrier or limit zoning it off from a

nonmaterial, nonphysical, or supernatural type of being. The only foundational being there was, was

material being, and some kind of natural substance underlay all visible phenomena. Lucretius called

this endless fact of material being the "All," and with d'Holbach and Buechner concluded it lacked

any plan or purpose and consisted of blindly opposing forces locked in an ultimately self-canceling,

cosmic equipoise or gridlock.

Of course these assumptions implied, secondly, the lack of any governance or management of the

universe by any sort of transcendental intelligence. From the start, materialism has been implicitly

atheistic, though its atheistic implications were not fully spelled out before d'Holbach did so in

his System. Materialism has always viewed atheism merely as a necessary consequence of its premises,

not as a philosophically important end in itself. Supernatural gods, spiritual deities, or immaterial

moralizers could obviously not be taken seriously, or for that matter even imagined to exist, in the

materialist hypothesis.

Thirdly and last, materialism has always assumed that life is wholly the product of natural processes.

All human thought and feeling emerges from the nonliving, inorganic matrix of physical nature and

ends at death. Lucretius believed that thoughts and feelings were literally made up of a film of very

fine atoms that peeled away from objects and recombined in the brain. D'Holbach believed that

thoughts and feelings were the end product of chains of physical causation rooted in atomic motion.

Buechner believed that thoughts and feelings were electrical impulses somehow shaped by the

human nervous system into coherent patterns. Moreover, though it's not widely known, Lucretius

and d'Holbach both theorized that organic life evolved from inorganic matter, though it was not

until Buechner's championing of Darwinian theory that materialism could justify the theory

scientifically.

So materialism has always inferred its theories from the best empirical evidence at hand and has as a

result always had its metascientific hypotheses scientifically confirmed, because the basic assumption

of valid science has also always been that nature is governed by coherent, discoverable physical laws.

Indeed, the triumphs of science in the 20th century have been so stunning that today a majority of

professional philosophers, at least in the English-speaking world, identify themselves as materialists

of one kind or another [2]. Because these contemporary materialists disagree on some issues, I'd like

to introduce you to modern materialism this evening by explaining some of its main concepts and

controversies.

When someone today describes himself or herself as a materialist, they generally mean they stand

somewhere in a spectrum defined at one end as reductive materialism [3] and at the other end as

eliminative materialism [4]. Reductive and eliminative materialism [5] describe the poles of the

process known as intertheoretic reduction. Intertheoretic reduction [6] refers to what happens when

a new scientific theory either better explains or else completely invalidates an existing scientific

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theory. If the new theory better explains the old one, it is said to have reduced it to a fuller, more

convincing explanation. A successful reduction of this kind was the incorporation and clarification

of Newton's laws of motion in Einstein's theory of relativity, or of Maxwell's laws of

electromagnetism in quantum theory.

The other pole of intertheoretic reduction, eliminative materialism, consists of the invalidation or

complete displacement of an earlier theory by a new one. Examples of this kind of elimination are:

the theory of demonic possession being eliminated by the theory of mental disease, the theory of

phlogiston being eliminated by the discovery of oxygen as the cause of combustion, or creationism

being eliminated by evolution as an explanation of the earth's history.

Obviously, modern reductive and eliminative materialists are allies in believing, as pre-20th century

materialists did, that science has always confirmed and will most probably always continue to

confirm the basic hypotheses of materialist philosophy: that is, first, that all reality is essentially a

material reality and that therefore, second, no supernatural or immaterial reality can exist; and, third,

that all organic life arises from and returns to inorganic matter. Their main disagreement is over the

mind-brain problem, which has been the focus of 20th century materialist debate.

The so-called mind-brain problem refers to the question of whether or not human consciousness is

reducible in all respects to scientific laws. In the 1960s and 1970s those materialists who said it is,

known as identity theorists (i.e. the mind is identical to the brain in all respects), were challenged by

other materialists known as property dualists [7], functionalists [8], or supervenience [9] theorists.

What all of these challengers had in common was a belief that in some way human consciousness

was irreducible to or inexplicable in terms of natural processes [10]. They held, for example, that so-

called qualia -- a person's experience of pain or of after-images of color, for example -- were unique

to that person and incommunicable and unknowable to anyone else. They argued further that such

properties of consciousness as qualia could not be translated into the terms of physical science in any

meaningful way and hence represented a reality not amenable to the laws of nature.

Moreover, these challengers doubted the reducibility of one person's consciousness to the same

series of physical events as that which underlay another person's consciousness, even though both

consciousnesses might depend on, or, in current philosophical jargon, be supervenient on, physical

events happening in each brain. Two different brains did not have to work exactly the same way,

much less intelligences that might be silicon-based rather than biologically-based but capable of

sharing thoughts or feelings with biological brains. The fact that the same mental experience might

be physically realized in different ways in two different biological or non-biological brains limited the

identity of mind and brain to at most a token identity [11] between a specific brain and its unique

mental experience. It invalidated broad, "type" identities between mental experiences and brain

processes in general.

To these objections, current eliminative and reductive materialists make the following reply. First of

all, they argue that qualia, or the private feels of one's own experience, are no more incorrigible -- no

more infallibly known by the individual -- than one's experience of the external world [12]. One's

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body and brain is just as likely to misrepresent internal as external experience. Pain can be

anaesthetized and disappear, even though the same knife continues to cut your skin. One can

hallucinate colors privately as well as publicly, and in fact the brain's moment-to-moment

reconstruction of the external world is arguably just as private an experience as that of one's qualia,

yet no one claims one's knowledge of the external world is infallible or incorrigible.

Secondly, a token identity between mental events and brain events is all that is needed for a robust

and defensible mind-brain reductionism. No reductive materialist needs to claim that every brain

works precisely the same way when it sees a tree, multiplies 2 times 2, or hears a Beethoven

symphony. All that is needed is a convincing theory of how brains in general succeed in producing

what we call consciousness from their visceral pulps and fluids. Since how the brain actually works is

today one of the least-understood and most hotly-debated subjects in science, I'd like to explain

briefly the most promising of these theories and in the process finish my discussion of philosophical

materialism.

Neuroscience has concluded that the firing, or spiking, of cells in the brain known as neurons is the

foundation of all brain functioning. Every brain has billions of these neurons, joined together in

billions of networks by tiny filaments called dendrites and axons. Incoming signals, in the form of

tiny electrical impulses generated by other neurons, pass down the dendrites to circuit-breaker-like

gaps around the neuron known as synapses, which chemically monitor all the incoming signals and,

when all the signals have reached the appropriate level, suddenly depolarize the electric differential

outside and inside the neuron and cause the neuron to fire, or spike. The neuron's fired or spiked

signal is then communicated to other neurons in the network down its axons. It takes roughly a

hundredth of a second for a neuron to spike and repolarize for a new spike, which means that a

neuron can fire at most a hundred times a second -- far too slow to complete the incredibly complex

tasks the brain can do almost instantly, like recognizing someone's face, identifying a note or two or

music as part of a song or symphony, or picking up a glass from a table.

This means that the brain is confined to what is known as the "hundred-step rule," or the fact that

the maximum number of sequential steps the brain can take in one second is about a hundred. Since

high-powered digital computers (computers that do all their computations sequentially, like a herd of

sheep passing one by one through a gate) can do millions of steps in a second yet are notoriously

poor at doing the perceptual and discriminatory tasks brains do with ease; the brain, it is theorized, is

not structured like a linear computer but like a vast number of multi-dimensional computers

working in parallel with each other.

In what sense is the brain a "multi-dimensional" computer? At bottom, the brain evidently works on

the same on-off, binary principle that governs all linear computers: like them, its basic language is

either "on" or "off" -- either spike/fire or not spike/fire. When a neuron spikes or fires, it does so in

mechanical, all-or-nothing fashion like a spark plug, entirely as a result of having reached just the

level of electrical excitation in its synapses it needs to make it suddenly depolarize. By themselves,

neurons are nothing but stupid, mechanically controlled switches.

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But when they are joined in networks whose signals parallel those of billions of other networks and

interact at critical points, the result is human consciousness. From a countless plethora of dumb,

electrical relay switches and settings emerges the amazing phenomenon we call human

consciousness and intentionality -- the ability to think about things, to feel a range of emotions, and

to realize one's self as a subjective entity distinct from the rest of the world.

How can this happen? How can something oblivious of the world become conscious of the world?

Though theoretical neuroscience is still in its infancy, furiously boiling with new ideas, some likely

answers are emerging from the steam. One promising theory is that networks of neurons in the

brain consist of subsidiary groups of neurons or even individual neurons that serve as the axes of a

multi-dimensional system of coordinates that can mathematically translate one kind of value to

another kind of value. For example, someone sees an apple hanging from a tree. His brain locates

the apple in an abstract visual space calculated in terms of how many degrees above a distant

horizon the apple is, how close to him the focusing of his eyes tells him the apple is, and so on. But

in order to pick the apple, his brain must translate its abstract visual calculation of the apple's

location into an abstract motor-muscular space which will tell the muscles of his arm at which angle

they will have to set themselves in order to approach the apple. What happens here, it is theorized, is

that an array of neuronal networks transforms the values of his visual space into those of his motor

space by means of a mathematical tensor, or formula, that translates the multi-dimensional

coordinates, or vectors, of visual space into the vectors of motor space -- all the angles of sight are

translated into angles of arm-bending. Although it does not seem so to the person reaching for the

apple, his behavior is the result of a vast number of mathematical computations in his brain, which,

because of its parallel computing capacity, it is able to carry out almost instantly.

Moreover, one of the brain's most impressive powers is that it is incredibly plastic and capable of

learning, especially in infancy and childhood. It may well learn by adjusting the synaptic openings, or

weightings, as they are called, of neurons individually and in networks so that the signals reaching

them must produce just the right polarity from just the right dendrites to fire. This could explain, for

example, why we recognize faces and other hard-to-distinguish sense experiences so quickly. Our

brain has so many neuronal networks available for use -- one researcher has calculated them as

totaling more than 10 to the 80th power -- that every single thing we learn may have its own

network set at just the right synaptic weightings to be activated only by that bit of learning. This

means that impulses coming into the brain from the senses are blocked from activating all but the

relevant network, which almost instantly verifies that it's granny's face at the door. And synaptic

weightings are flexible enough to readjust to changing circumstances if necessary.

The bottom line of this theoretical approach, of course, is that the mind is reducible to natural

processes that can be translated into the language of math and physics. Neuronal networks are

computing mechanisms that effortlessly transform multi-dimensional vectors of one kind of

mathematical value into other vectors of mathematical value. Visual space being changed into motor

space has been mentioned, but a great deal of work has already also been done along these lines on

how we see and hear. Images from the eyes' retinas are translated into neuronal signals and

processed through countless neural networks simultaneously so quickly that it seems to the viewer

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she is seeing the external world on a mirror in her mind, whereas in fact her brain is recreating and

re-representing everything "out there" from, as it were, scratch. So too with sound. Varying air

pressures entering the ear are translated into electrical impulses which are then massively and

instantly parallel-processed into noises that seem to be coming to us, direct and unmediated, from

the external world. But in fact they too, like our vision, are the result of incredibly complex

processes of vector transformation among multi-dimensional coordinate systems performed by the

countless neural networks of our brain.

Most reductive and eliminative materialists agree that the theory of mathematical transformations

just sketched is one of the most promising explanations we have of how our brains work. But the

eliminativists hold that the theory is so revolutionary and so much more convincing than current

theories of the brain -- for instance, that the brain is basically propositional and language-oriented --

that it will eventually displace and replace the linguistic theory, just as the modern theory of mental

disease displaced the medieval theory of demonic possession. Against them stand the reductive

materialists, I among them, who share their enthusiasm for the new theory but believe that it will

successfully reduce at least portions of the old theory the way Einstein's relativity successfully

reduced Newton's laws of motion.

A couple of further comments on reductive materialism are in order. First, what is the status of

mathematical concepts like numbers, mythical figures like river nymphs, comic-book characters like

Donald Duck, and the like? Non-reductionists argue they are non-material, non-physical entities that

are able to influence the physical world yet are inexplicable in terms of natural laws[13]. While

granting a fictional, artificially man-made status to such phenomena, reductionists, on the other

hand, argue that they do physically exist. Even when they are not physically embodied, say, in maps,

epic poems, or comic books, they are actively or passively realized in the brains of intelligences

capable of understanding and communicating them. In other words, all such ideas must be created,

remembered, and transmitted in the form of appropriately processed neuronal firings by conscious

intelligences to have whatever effect they do have outside those intelligences. They are in fact always

physically embodied, either in brains or in the artifacts produced as a result of conscious effort.

When and if no brain ever again lights up with the concept or memory of them, they have ceased to

exist in that form, though most of the atomic elements which have produced them in brains in the

past and could again produce them in the future will probably persist in some form as long as our

present cosmos persists. To the reductionist, human thought and feeling are most definitely material

entities capable of influencing other material entities like mountains, rivers, metal ores, and electric

and nuclear energy in huge and spectacular ways.

The reductionist takes a similar approach to a second objection often raised by non-reductionists:

Moral concepts, they say, are not reducible to natural process and physical law. In contrast, the

reductionist, convinced that all life is the product of natural selection, sees morality as fundamentally

the result of evolutionary survival. Social cooperation, love of one's mate, offspring, relatives, or

tribe, repugnance to the murder of one's own species, and the like, are the reverse side of the coin of

virtues like social competition, hatred of one's enemies, successful prosecution of war and the killing

of one's own species, and the like. They are essentially the residue of human experience on the face

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of the planet, as are the invention of gods, of creation myths, of apocalyptic destructions of the

world, and so on. Furthermore, the reductionist equates moral discrimination with sense

discrimination. That is, the ability to sense a difference between heat and cold, light and dark, acid

and alkaline is indistinguishable from the ability to decide whether this thing or place or experience

is better or worse than that thing, place, or experience. Physical sensing and moral judgment have from

the start been simultaneous and identical processes, and even the most refined and abstruse moral

reasoning is rooted in the slime and grit of earth's natural history. Human beings are moral to the

core, not because a deity has commanded them to be or because they've chosen to be but because

natural selection has forced them to be[14].

Finally, reductive materialism applauds and identifies itself with the stunning success of the reductive

program of 20th century science as a whole. It regards such triumphs of human intelligence as the

establishment of the periodic table of elements and of the standard model of elementary particles as

surely among humanity's greatest achievements. The periodic table and the standard model are

outstanding examples of the relentless effort of scientists in this century to uncover deeper and

deeper levels of physical explanation and to reduce their findings to more and more comprehensive

and fundamental theories. Equally outstanding has been the effort to unify the four basic forces of

nature at greater and greater levels of generalization. Already it has been proven that two of the four

forces, electromagnetism and the weak nuclear force, were unified at energy levels that are theorized

to have existed until a billionth of a second after the Big Bang had passed, after which they split. At

a still earlier moment, it's theorized that the electroweak force was unified with the strong nuclear

force, and at a still more primordial moment before that -- the so-called Planck era, when the

universe was still less than 10 to the minus 43rd seconds old and seethed with a thousand million

billion billion volts of energy -- the electroweak and strong nuclear forces were still unified with the

fourth force, gravity. Modern scientific reductionism has succeeded in showing that the manifold

phenomena of physical nature -- light, heat, rocks, flora, fauna, consciousness -- are probably

manifestations of a single, foundational, material reality, perhaps ultimately describable in the terms

of some future human science. Materialism welcomes this success as further confirmation of its

2500-year-old hypotheses.

[Richard C. Vitzthum is the author of Materialism: An Affirmative History and Definition (Buffalo, NY:

Prometheus Books, 1995).]

Endnotes (by Keith Augustine)

[1] One may object to Vitzthum's contention that the universe is infinite in extent and has existed

eternally as being contrary to modern cosmology. The consensus view of modern cosmologists is

that the universe--that is, all space and time--was created fifteen to twenty billion years ago with the

Big Bang. Furthermore, physicists like Stephen Hawking have proposed that we live in a finite yet

unbounded universe (see Hawking's A Brief History of Time). It is clear from his Materialism: An

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Affirmative History and Definition that Vitzthum does not dispute either that the Big Bang was the

creation of the space-time manifold we inhabit or that Hawking's finite yet unbounded universe,

where there simply is no 'before' the Big Bang (since the Big Bang created time) any more than there

is a place north of the North Pole, may be true. In such a view, the Big Bang doesn't result from a

fireball spontaneously appearing from absolute nothingness, but rather it doesn't make any sense to

speak of a time before the Big Bang. The Big Bang would simply be time zero from which the

universe began. Other possibilities are that the universe is just one out of an infinite number of

universes that preceded it through a Big Bang--Big Crunch--Big Bang cycle (such a view introduces a

hypothetical metatime that is completely independent of time as we know it), that the Big Bang

emerged from a quantum fluctuation in some quantum universe completely independent of and

isolated from the universe we inhabit (quantum genesis), or that our universe formed when a black

hole in another universe pinched off and became causally isolated from ours. Perhaps our universe is

just one of an infinite number of other universes; or perhaps our universe is the only universe that

ever was, is, or will be.

[2] Materialism has enjoyed widespread acceptance among well-educated twentieth-century thinkers.

In the Preface to Contemporary Materialism: A Reader, Paul Moser and J. D. Trout write: "Materialism,

put broadly, affirms that all phenomena are physical... Materialism is now the dominant systematic

ontology among philosophers and scientists, and there are currently no established alternative

ontological views competing with it" (p. ix). Jaegwon Kim, a philosopher at the forefront in the

philosophy of mind, agrees: "There has been a virtual consensus, one that has held for years, that the

world is essentially physical, at least in the following sense: if all matter were to be removed from the

world, nothing would remain--no minds, no 'entelechies', and no 'vital forces'... [M]ental states and

processes are to be construed as states and processes occurring in certain complex physical systems,

such as biological organisms, not as states of some ghostly immaterial beings [i.e. souls]" (p. 579 of

"Mind-body problem, the" by Jaegwon Kim in The Oxford Companion to Philosophy edited by Ted

Honderich).

[3] Reductionist materialism holds that mental states are identical to brain states, "that facts about

mentality are reducible to physical facts, i.e. facts about matter and material processes" (p. 751 of

" Reductionism, Mental" by Jaegwon Kim in The Oxford Companion to Philosophy edited by Ted

Honderich). On a reductionist view, there is nothing about consciousness that is "over and above"

physical brain processes.

[4] Eliminative materialists contend that minds don't exist, that our 'vague talk' about things like

feelings, thoughts, desires, etc, needs to be eliminated from our vocabulary and replaced with precise

scientific terms referring only to brain states. In his Preface to the Paperback Edition (1992) of his A

Materialist Theory of the Mind, David Armstrong confesses: "One Materialist theory I have never been

drawn to is the Eliminativist account of the mental... If I were to become convinced that there is an

incompatibility between a materialist or physicalist view of the world and the existence of the

mental, then I would reluctantly turn Dualist. Materialism is a theory, even if, as I think, a good

theory. The existence of mental things--pains, beliefs, and so on--seems to me to be part of bedrock,

Moorean, commonsense. Its epistemic warrant is far better than that of Materialism" (p. xix).

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[5] In the March 25, 1996 edition of Time Magazine, an article by Robert Wright titled "Can Machines

Think?" raised the question of how eliminativism and reductionism differ, or in Wright's words,

"Some laypeople (like me, for example) have trouble seeing the difference between... saying

consciousness doesn't exist and saying it is nothing more than the brain." The question can be

restated as follows: Since both eliminativists and reductionists believe only in physical substances

and properties, how do these two points of view differ? If the mind is physical, what does

reductionism have that eliminativism lacks, since both only admit the existence of the physical? The

article argues that advances in artificial intelligence only amplify what Wright calls the "extraness" of

consciousness, the fact that one can explain human behavior in purely physical terms without ever

invoking a the idea of mind, implying that consciousness must therefore be "over and above" the

brain. In this article David Chalmers proposes that one could imagine a universe exactly physically

identical to the universe we know yet without consciousness as an argument in favor of property

dualism.

[6] The reductionist's claim that mental states are identical to physical brain states is an example of

intertheoretic reduction. Several examples of intertheoretic reduction exist in science: Lightning is

identical to an electrical discharge; water is identical to H2O; light is identical to electromagnetic

waves; sound is identical to compression waves traveling through a medium; genes are identical to

the DNA molecule, etc. These examples all share one very important feature: They are all cases

where our common-sense framework has been reduced to a new conceptual framework.

[7] Property dualism holds that nonphysical substances or things do not exist (e.g. immaterial souls

which make organisms conscious, vitalist 'life forces' which make organisms alive as opposed to

inanimate, and deities and other 'spiritual' beings), but that there are nonphysical properties of physical

matter. Among this class of nonphysical properties are what we call mental states, and they are

produced by physical brains. For the property dualist, only physical substances exist, but these

physical 'things' can have physical or nonphysical properties. Consciousness, it is argued, is a

nonphysical property of the brain because it doesn't have properties commonly associated with

physical phenomena (e.g. mass, shape, size, density, electric charge, temperature, position in space,

etc).

[8] Functionalists claim that mental states are functional states (rather than brain states) which

connect input (environmental stimuli), other mental states (interconnected functions), and output

(behavioral responses) in a cognitive system by means of causal relations. Jaegwon Kim explains this

definition as follows: "Pain, for example, is to be understood in terms of its function as a causal

intermediary between sensory input (e.g. tissue damage), behaviour output (e.g. wincing), and other

mental states (e.g. desire to be rid of it). Most functionalists are physicalists [materialists] in that they

hold that only appropriate physical states could serve as such causal intermediaries. But they... [hold

that] mental properties cannot be identified with physical-biological properties. And functionalism

construes psychology as a scientific study of these functional properties [while neuroscience is

distinguishably the study of neural properties] and kinds, specified in terms of their causal roles...

This view of psychology... is, arguably, the received view of the nature of cognitive science" (p. 580

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of "Mind-body problem, the" by Jaegwon Kim in The Oxford Companion to Philosophy edited by Ted

Honderich).

[9] Jaegwon Kim defines supervenience as the idea that "once all the physical facts about your body

are fixed, that fixes all the facts about your mental life... [W]hat mental properties you instantiate is

wholly dependent on the features and characteristics of your bodily processes. This 'supervenience

physicalism' may be regarded as... the weakest commitment any physicalist must make" (p. 580 of

"Mind-body problem, the" by Jaegwon Kim in The Oxford Companion to Philosophy edited by Ted

Honderich). Kim also points out that "[o]thers maintain that the mind-body relation is adequately

characterized as one of 'supervenience'--that is, in the claim that there could not be two entities, or

worlds, that are exactly alike in all physical respects but differ in some mental respect... [T]he

reductionist, the functionalist, and even the epiphenomenalist are all committed to mind-body

supervenience" (p. 576 of "Mind, problems of the philosophy of" by Jaegwon Kim in The Oxford

Companion to Philosophy edited by Ted Honderich). Epiphenomenalism is a type of property

dualism which contends that mental states are mere nonphysical by-products or effects of neural

firings that themselves have no effects on the physical world--including the brain--whatsoever.

[10] Naturalists (from philosophical naturalism) might object that human consciousness is

totally natural--i.e. not supernatural--yet still nonphysical (lacking physical properties). In such a view,

natural would be seen as being more inclusive a term than physical: e.g. a naturalist might believe

that the term natural encompasses everything physical, nonphysical mental states, and perhaps

nonphysical abstract objects like numbers. To a reductionist materialist, 'natural' is synonymous with

'physical'.

[11] A materialist theory of the mind which invokes a token identity maintains that each instance of a

mental type is identical to each instance of a physical type. That is to say, mental states aren't

exclusively identified with brain states, as they are in a type identity. A token identity allows the

possibility that the same mental state--pain, for example--could be instantiated not only in the

human brain but also in different physical systems, such as computers or radically different alien

brains. The type-token identity distinction can be illustrated in other phenomena in nature: lightning

is a type identity because it is a category (or type) of natural phenomena that is identical to a category

of electrical discharge. A single lightning flash is a token identity: An individual flash of lightning is

token identical to an individual electrical discharge. Thus, the broader type identities refer to classes

of objects or events, whereas token identities refer to specific cases. A token identity is an essential

characteristic of functionalism.

[12] Although the view that one can know his own mental states incorrigibly has been defended by

nonreductionists like John Searle, this position is not a necessary assumption of all forms of

nonreductive materialism. A nonreductionist might argue, for example, that he does not know his

own qualia or subjective experience infallibly, but that he does know that what he has access to in

introspection is nonphysical subjective experience.

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[13] One should understand here that nonreductionists also grant a fictional status to concepts such

as river nymphs and comic-book characters. A nonreductionist argument is that numbers, sets,

universals, and other abstract objects exist independently of the physical world. David Armstrong

has commented on this: "Suppose... that there is a transcendent realm of numbers. How

scientifically-implausible to think that this realm, or members of this realm, can act on brains!" (p. 38

of "Naturalism, Materialism, and First Philosophy" by David Armstrong in Contemporary

Materialism edited by Paul K. Moser and J. D. Trout).

[14] An evolutionary account of the origin of moral judgment in human beings does not tell us what

(if anything) makes a specific action moral. On a materialist view, all codes of conduct must

ultimately be man-made or socially constructed; there are no objective moral laws existing

independently of sentient beings in the way that laws of nature do. Thus there are no objective criteria

for determining if human actions are right or wrong. The objectivity of laws of nature is clear--our

approximations to them (laws of physics) are publicly falsifiable and can be corroborated by

empirical evidence. Moreover, unlike natural laws, moral laws can be violated. But if what we call

moral laws are really man-made inventions, our ethical rules are arbitrary and thus individuals are not

obligated to follow them. Nothing makes an action objectively moral or immoral; individual and

social codes vary because ethics, like beauty, is in the eye of the beholder. But then there are no

compelling grounds for arguing that Aztec human sacrifice, Nazi or Serbian genocide, or infanticide

is really wrong. Core ethical rules are no doubt determined by intersubjective consensus across

cultures--for example, incest and murder are universally prohibited. But such consensus does not

demonstrate the objectivity of ethics; it merely demonstrates that human beings or societies are

largely 'built' the same way and react similarly to certain types of behavior. Suppose we have

inherited an aversion to committing murder. That such a genetic disposition would be widespread

makes evolutionary sense. A known murderer's neighbors will fear that the murderer might kill

them. Out of mutual self-interest they would be wise to band together and eliminate the murderer

before he could eliminate them. Since murderers would tend to be eliminated before they could

reproduce, individuals with a genetic inclination to commit murder would tend to dwindle. But this

is merely an accident of natural selection, and trying to base morality on the fact that adhering to

certain ethical norms will make you more "fit" to stay alive and reproduce is insufficient. The origin

of behavior is irrelevant to whether a behavior is right or wrong; what makes an individual

evolutionarily 'fit' (e.g. infidelity) is not necessarily moral. There will no doubt still be some

individuals who are genetically inclined to commit murder; but we do not conclude that the are

exempt from moral prohibitions on murder because of this. Furthermore, the fitness of certain

evolutionary traits changes when the environment changes. Would murder suddenly become morally

acceptable--even obligatory--if it provided us a selective advantage? On a materialist account, the

only foundations for behavioral codes are preserving self-interest and satisfying one's conscience--

there are no additional 'moral facts' which motivate behavior.

12

Further Reading:

 Materialism (Routledge Encyclopedia of Philosophy)

 Epicurus (Internet Encyclopedia of Philosophy)

 The Epicurus Reader: Introduction (D.S. Hutchinson)

 Lucretius (Internet Encyclopedia of Philosophy)

 D'Holbach's Common Sense (excerpts)

[Note: The listed publication date is erroneous; Common Sense appeared in 1772]

 Baron d'Holbach: A Study of 18th Century Radicalism in France (Max Pearson Cushing) [text]

 Baron d'Holbach (Stanford Encyclopedia of Philosophy)

 Baron d'Holbach (Skeptic's Dictionary)

 Ludwig Büchner (PDF download, Routledge Encyclopedia of Philosophy)

 Ludwig Büchner biography (Spanish) [translate]

 Büchner's Force and Matter, 1855 ed. (Spanish) [translate]