The Demise of Neutral Monism Due to the Simplicity Intuition

Neutral monism is the view that there is only one fundamental substance, neither physical nor mental, but neutral in nature. On this view, the world's neutral state determines both its mental and physical state. A central motivation for neutral monism is that it purports to provide for a solution to the mind- body problem. According to this solution, aggregates of neutral substance are conscious. A second motivation for neutral monism is that it purports to provide an explanation of the behavior of elementary particles. By this explanation, the neutral essences of elementary particles determine their physical behavior. It is my aim to show that neutral monism is false. My argument has two parts. First I will undermine the central motivation for neutral monism. I will do this by arguing that conscious beings are simple, that is to say, they are not composed of other things. Because conscious beings are simple, aggregates of neutral substance cannot themselves be conscious. And so, the neutral monist's solution to the mind-body problem is undermined. Second, I will show that only physical essences are a plausible candidate to explain the physical behavior of elementary particles. In section (1), I will explain the theory of neutral monism. In section (2), I will explore three conundrums presented by neutral monism. In section (3), I will defend the theory of our simplicity intuition applied to conscious beings. I will demonstrate how the theory of simplicity is in fact a sufficient counter argument to neutral monism. In section (4), I will explore superior objections to the simplicity intuition argument. In section (5), I will summarize David Chalmers mistake of surrendering to neutral monism, in his book The Conscious Mind. I will also discuss the general philosophical implications of surrendering to neutral monism. In section (6), I will explain that physical essences are the only plausible candidate to explain the behavior of these elementary particles, which neutral substance is theorized to govern. For all of its value, I believe Chalmers’ argument for neutral monism is constructed from weak premises and is unsound. In the interest of brevity, it is not my intention to support any justified solution to the mind body problem. I only mean to prove neutral monism false. In the end, I will touch on materialism, in comparison to the failed neutral monism. This paper will strictly focus on neutral monism and simplicity.

(1) Neutral Monism

Neutral monism classifies as a monistic metaphysical theory. Proponents deal the substance monistic argument in a drove of variety. What characteristic all variations hold in common is the concept of singularity: there exists one fundamental substance which underlies all concrete objects (physical and mental). Substance monism can be divided into the 3 kind, idealism: the one fundamental substance is strictly mental, materialism: the one fundamental substance is physical, and neutral monism. These different variations of substance monism arrive at conflict when determining what realm of existence constitutes this fundamental substance. The majority of neutral monist proponents believe that all physical and mental properties are created from and reduced to this fundamental neutral substance. This substance is believed to be neither physical nor mental thus conveying the idea of neutrality. I will be addressing a form of neutral monism which states that this neutral property constructs the intrinsic nature of the elementary subatomic particles that constitute our physical existence. When aggregated in specific states these same particle features supposedly possess consciousness. To understand this neutral monism we must know (1) the intrinsic nature of the neutral reality, (2) the correlating bond between the perceived Arete physical state and the neutral property, and (3) the correlating bond between the phenomenal experience (mental) and the neutral property. Proponents of neutral monism have the tendency to call the reality between mind and matter “neutral stuff”. We do not know the intrinsic nature of this neutral property; however, this neutral property is theorized to govern certain fundamental particles in our physical world.

(1) To understand the nature of the neutral state we must understand the modern physical science’s outlook on elementary subatomic particles. Neutral monism thrives on our current limitation of knowledge in quantum mechanics. With current technology, we have yet to discover the intrinsic nature of subatomic particles, such as quarks and leptons. We have the ability to observe these particle’s actions and their governing features. We can measure mass, movements, quantum tunneling, electrical charge, and spin. We can observe how these particles react with other particles and construct mathematical formulas to predict certain future behavioral features. However, we do not currently know the intrinsic nature of these particles. By this I mean to say that we do not know the nature of the governing features (spin, charge, etc). Quarks and leptons are classified as elementary particles: particles that possess no substructure, and are the smallest things known to man. These particles construct larger particles such as protons, neutrons, etc. These larger particles then turn to construct atoms, which construct our physical state. Bertrand Russell, who was a proponent of neutral monism said, “Its (elementary subatomic properties) relation to the object (elementary subatomic particles) is causal and mathematical; we cannot say whether or not it resembles the object in any intrinsic respect, except that both it and the object are brief events in space-time”. When asked what “charge” is, a quantum physicist will state “it is a property carried by certain elementary particles”. When asked what controls the elementary particle’s charge, physicists will shrug their heads and hand you a calculation trying to predict a specific particle’s future actions based on the observed charge. Proponents of neutral monism say that the neutral reality governs these particles and constitutes their intrinsic nature. Neutral monist proponents believe the neutral substance is responsible for a quarks charge, spin, etc. Chalmers (proponent of neutral monism) uses the term “protophenomenal property” when referring to the governing neutral substance. I will follow Chalmers and use this term protophenomenal property, for I believe it accurately reflects the definition of the neutral property. (2) The intrinsic relationship of our perceived physical state and protophenomenal property is complex. The perceived physical reality exists as a constructed entity of the protophenomenal state. Because the protophenomenal property would govern the state of these fundamental particles (quarks and leptons), it would in turn control the larger particles which these particles construct (protons, neutrons, etc), and in turn control entire atoms themselves, which compose and govern the physical nature of all objects. The physical world would hold no existence or action in absence of the protophenomenal substance. The state of the protophenomenal substance qualitatively determines the state of the physical world. Physical properties would logically supervene on protophenomenal properties. Our entire physical existence would directly supervene from a qualitatively specific protophenomenal property. (3) Protophenomenal substance holds a constructing relation to phenomenal consciousness as well. When qualitatively specific aggregates of protophenomenal substance are composed, they possess an extrinsic feature of consciousness (e.g. conscious cognitive matter). Certain protophenomenal properties possess conscious experience, theoretically depending on their arrangement and relation to each other. Phenomenal consciousness logically supervenes from the neutral state. All mental sensation The Demise of Neutral Monism Due to the Simplicity Intuition and experience is ultimately composed from different protophenomenal property conglomerations. The phenomenal consciousness is strictly an experience receptor for certain neutral states. Not all protophenomenal states need phenomenal consciousness. Theoretically, an aggregate of protophenomenal properties that construct a table would most likely not possess consciousness. An aggregate of protophenomenal properties that construct a human brain would have the feature of consciousness. An example for clarity, so we may view the relation between the neutral, mental, and physical. “I see red”. This sensation «red» is a creation of my protophenomenal state. Certain protophenomenal properties conglomerated in a qualitatively specific structure. This conglomeration constructs a physical state of a certain “red” property. This physical state of «red» was simply projected through the certain configuration of multiple subatomic particles. Because the mental state simultaneously supervenes from the protophenomenal state, I have this phenomenal experience of red, however it is just a feature of my protophenomenal state, imaging itself into my perceived consciousness. On the next page I have created a simplified diagram, which illustrates the process occurring in a human brain under the governance of the neutral monist theory. Some possible protophenomenal states are in the middle column. Each one of these qualitatively different protophenomenal states gives rise to a corresponding physical state (right column) and phenomenal experience (left column) simultaneously.

Neutral Monism Process

PHYSICAL  PROTOPHENOMENAL  PHENOMENAL

0 1 0 0 0 0 Quark/Lepton Property Green Experience 0 0 0 0 1 0  # 2739581309849374  -Top right 0 0 1 0 0 0 -Causes certain green belief visual field 1 0 0 0 0 0 in top right visual field

0 0 1 0 0 0 Quark/ Lepton Property Cold Experience 1 0 0 0 1 0  #23987530298745937  -Left index finger 0 0 0 0 0 0 -Causes belief of cold temperature 0 1 0 0 0 0 in left index finger

1 0 0 0 0 0 Quark/ Lepton Property Scent of Roses 0 0 1 0 0 0  #32098459028632908  -Nasal Apparatus 0 1 0 0 1 0 -Causes smell belief of red roses 1 1 1 0 0 0 through nasal apparatus

Neutral monism is carried out by a theorized set of governing protophenomenal laws. Because we have a completely different state of reality (neutral), new governing laws must exist for this neutral state. This neutral reality will require laws of a different nature to govern the physical (quarks/leptons), as well as the mental (phenomenal experience). The three illustrated protophenomenal states are categorized by number. This number represents the qualitative state of all protophenomenal properties in the brain at that instance. This state in turn governs the qualitative state of all quarks and leptons in the brain. The numbers are very large because Arete there are a large amount of possible qualitative states that the protophenomenal properties could possibly form. We can imagine a trillion qualitatively different sensations of just the color “red” that a conscious individual could experience. Now imagine every single different sensation that a conscious being could experience. The “physical” column illustrates the different particle configurations created from the neutral property. The matrix shows 24 elementary particles (obviously the human brain possesses a much larger quantity of quarks and leptons), and each elementary particle is represented by a 1 or 0. The 1 represents a particle with positive charge, and the 0 representing a particle with negative charge. Obviously elementary particles are under governance of many more properties then just charge, but for our simple purposes I will differentiate between particles with only a charge feature. Remember that charge is simply a form of governance which the protophenomenal property uses to create specific physical states. The phenomenal column illustrates the corresponding sensation, simultaneously experienced by the conscious subject, during each neutral monism process.

(2) Conundrums Presented by Neutral Monism

I will explore three puzzles that neutral monism presents. The first puzzle comes from our lack of sufficient detection method for the theorized “neutral substance”. We cannot know if the neutral monism theory is correct, for we have no process to discover this supposed protophenomenal state with current scientific technology or cognitive theory. This would in turn create the problem of detecting phenomenal consciousness, because protophenomenal substance would ultimately determine the phenomenal consciousness. The second puzzle arises because there is a theoretically vast number of qualitatively different states that aggregated protophenomenal features could compose. There is an epistemic possibility that a specific protophenomenal state can give rise to a corresponding specific physical state, and not possess a corresponding conscious experience to accompany that specific physical state. I mean to say, it would be possible for unconscious zombies to exist. We would have no method of recognizing their lack of phenomenal consciousness. This is because we have no scientific method or cognitive study for detecting consciousness. The third puzzle is created from our knowledge gap of the theorized protophenomenal laws. There is a possibility that multiple protophenomenal states which are qualitatively different, could give rise to the qualitatively same physical state. We would have no way of knowing which one of those variously distinct protophenomenal states was constructing that particular physical state. Since we cannot detect the protophenomenal feature or the phenomenal feature we would also be unaware as to which of those variously distinct protophenomenal states gives rise to the correlating phenomenal experience. This third puzzle presents a scenario in which it would be impossible for there to be zombies physically identical to us. If the zombies possess our identical physical state, that means that they either possess our identical protophenomenal state, or a different protophenomenal state that gives rise to the same physical state. If the zombie possesses our identical protophenomenal state, we can be sure they are not zombies because that state necessarily gives rise to conscious experience (since we are in that qualitative physical state, and can know that we are experiencing phenomenal consciousness). However, the protophenomenal state might be non-identical to our protophenomenal state. The zombie's protophenomenal state may or may not give rise to a correlating consciousness. In this case it would be impossible to know whether the zombies were experiencing consciousness or not. Below I have illustrated this third puzzle. You can see 3 qualitatively different The Demise of Neutral Monism Due to the Simplicity Intuition protophenomenal states. We are undergoing Protophenomenal State 2. We know this because we are conscious and Protophenomenal State 2 is the only state which possesses consciousness. All 3 of these states give rise to an identical physical state. Protophenomenal State 1  Phen. State 1 Physical State 1 Correlating  Protophenomenal State 2  Quark/Lepton Config. Experience (Charge/Spin/Etc) Protophenomenal State 3 

(3) The Simplicity Intuition

I intend to show that conscious beings are simple and are not composites. Conscious beings cannot be composed of multiple entities of any nature, including neutral substance. I mean to say the an aggregate of protophenomenal properties cannot possess consciousness. We can know from a zombie or inverted spectrum scenario that phenomenal consciousness cannot be strictly derived from physical properties. That is why this “buffering” protophenomenal state seems like it could solve the mind-body problem. However, I believe that neutral monism is a scapegoat which simply arises from a temporary lack of scientific knowledge. I believe that neutral monism can be argued false. I plan to show this through our simplicity intuition about phenomenally conscious beings. The neutral monism view depends on phenomenal consciousness arising from an aggregation of protophenomenal properties within one’s cognitive matter. That is stating that a collection of multiple entities possess phenomenal consciousness, which is absurd. It would not matter if the subatomic particles were all of the same material and composition and acted in systematic accordance with each other. We can know that these multiple protophenomenal properties cannot give rise to a single phenomenal consciousness. I believe this intuition of simple beings applies to all physical, mental, and neutral things throughout our existence, including protophenomenal features of quarks and leptons. I intend to show that (1) Conscious beings are simple. Multiple objects cannot coalesce and give rise to conscious experience. (2) It is absurd to accept that nature, relation, and environment have effect on premise (1). (3) Based from premise (1) and (2) the simplicity intuition applies to protophenomenal properties in the same fashion it does to physical objects. (4) Therefore, neutral monism is a crackpot theory that ends up false. Our only current method for testing this simplicity intuition is by a priori justification, hence the term intuition. We have no a posteriori scientific method of testing for phenomenal consciousness or protophenomenal property. David Chalmers raised an example to prove this, through a scenario in which you have a physically identical zombie, and this zombie appears to be talking about and describing his phenomenal experience (which doesn’t exist). The zombie is describing his perceptual sensations, and worse yet, he starts talking about his identical zombie which he says has no phenomenal experience. Because of metaphysical possibilities like this combined with a lack of sufficient a posteriori testing we can only rely on our a priori intuition to study phenomenal consciousness.

(1). Conscious beings are simple and cannot be composed of multiple entities. Consider my identical twin and I. We are standing next to each other, and I feel a pain Arete experience in my stomach. My identical twin also feels the qualitatively identical pain experience in his stomach. Can we possess a unified consciousness? No, it is absurd to believe that at that exact moment, my twin and I could be experiencing a unified sensation of stomach pain, euphoria, fear, or tasting paint chips. David Barnett believed “Pairs of people themselves are incapable of experience” . I agree, because conscious beings are simple and are not composed of parts. It is true, that there are more quarks and leptons then just a pair which constitute our cognitive matter, however this matters not. Imagine Putnam’s “swarm of bees” example. Could a swarm of bees feel pain in itself? Is there something it is like to be a swarm of bees? The logical answer is no to both. It matters not how many bees are within the swarm, they do not themselves experience any sort of unified phenomenal consciousness. Think of the absurdity if conscious beings were composites, and not simple. Lets take a pair of carrots for example. Each carrot is an individual object, and qualitatively identical to the other carrot. But, there exists a possible aggregation of the pair of carrots in which the following are possible. Each individual carrot remains qualitatively the same as if they did not compose the pair of carrots. The pair of carrots possesses a new intrinsic feature which neither of the individual carrots possess. This pair's new feature is not metaphysically determined by its individual members. This new intrinsic feature is consciousness. Regular pairs of carrots do not possess this new feature, nor the possibility to aggregate in such a way that they produce this new intrinsic feature. A property dualist might object and stipulate the following. A conglomeration of subatomic particles composing our cognitive matter necessarily possesses the feature of phenomenal consciousness. However this is false: these subatomic particles cannot have consciousness. We know this from the following reasons. We know that phenomenal properties do not necessarily logically supervene from physical properties (subatomic particle configuration). We know this from Descartes’ zombies scenario. We can also counter the property dualists with an inverted spectrum scenario: imagine a twin-earth scenario where all physical characteristics are identical to ours, however, the physically identical inhabitants undergo an inverted spectrum of phenomenal experience to correspond to the physically identical world. Because of these 2 possibilities (zombies and inverted spectrums), we know that phenomenally conscious beings are not constructed of multiple entities; including aggregates of strictly physical subatomic particles.

(2). It is absurd to accept that nature, relation, and environment of a composite's members have effect on premise (1). It is possible, although highly unlikely, that intrinsic nature could alter the ability for a group of members to have a unified consciousness. It is no less absurd to believe that a pair of chairs, apples, computers, or subatomic particles could be conscious then it is to believe a pair of humans could. Intuition tells us that it is highly improbable to believe that the intrinsic nature of a pair or group has anything to do with the ability to produce a unified consciousness. The simplicity of consciousness is blind to the intrinsic nature of its entities.

I do not believe that environment or dispositional relation have the ability to counter our general simplicity intuition either. Could they have something to do with consciousness? Possibly, but general intuition will tell us otherwise. Consider David Barnett’s example posed as follows.

“Allowing for some radical changes to the laws of nature, imagine that some clever The Demise of Neutral Monism Due to the Simplicity Intuition

scientists shrink you and me down to the size of McCartney’s left and right brain hemispheres, respectively. The scientists then train us to function, at a relevant level, just as our respective hemispheres function: in terms of exchanging signals with the peripheral neurons and each other, we are trained to behave just as our respective hemispheres behave. McCartney’s left and right hemispheres are then removed and replaced with you and me, respectively. Someone pinches McCartney’s right arm (or his former right arm, should McCartney not survive the ordeal). When the signal arrives at the top of the spinal cord, I identify it; I notify you; we stimulate certain outbound neurons; and we move into a new functional state. As a result, McCartney’s head turns and faces his right arm; an irritated look appears on his face; and out of his mouth comes the words, “Stop that!” On a relevant functional level, you do just what McCartney’s left hemisphere would have done. And I do just what McCartney’s right hemisphere would have done. At a relevant level, the causal-dispositional relations borne by you and me are those that McCartney’s two brain hemispheres would have borne. Together, you and I function like an ordinary human brain. Given our new relations to each other and our environment, is it any less absurd to think that the pair we form might itself be conscious? No. To be sure, there is nothing absurd in the idea that McCartney might somehow survive the procedure; though unlikely, perhaps he would remain conscious throughout the ordeal. What seems absurd, rather, is that the pair comprising you and me might be conscious. Variation in how two people are related to each other and their environment has no significant effect on the absurdity of the idea that the pair itself might be conscious”.

Barnett’s example conveys that the simplicity intuition shows us that environment and dispositional relation really have no effect on a pair of things; the members, phenomenally conscious or not, giving rise to a unified experience in itself. Since environment, relation and nature do not affect a pair of people's ability to experience in itself, they should not affect a swarm of bees, or a conglomeration of subatomic particles ability to do so.

(3). Based from premise (1) and (2), the simplicity intuition applies to protophenomenal properties in the same fashion it does to physical objects. Since nature does not alter results of the a priori intuition, the nature of a protophenomenal property should hold no difference to simplicity whatsoever. It is true that we can only examine physical and phenomenal entities, but this should not matter. For we find no difference within the physical and phenomenal no matter the nature of the property. It is absurd to think that these protophenomenal laws break the simplicity intuition due to a different nature of sorts. It is preposterous to imagine a property, that when coalesced with other entities of that property or any other property, possess a unified phenomenal consciousness. A neutral monist proponent might object and say the nature of a composite's members could have consciousness if the the members possess a nature which we are unexposed to, i.e. protophenomenal property. They would say that because we have never dealt with protophenomenal property, which constructs pairs from multiple entities, we form false intuitions that conscious beings are simple. I believe this view to be unsound. It is my firm conviction that, no matter what the multiple members natures are, they cannot compose a unified conscious being!

(4) Neutral Monism is unsound. Arete

When the previous three premises are put together, the argument points to the conclusion that neutral monism is a crackpot theory. When tied together my argument goes as follows.

Simplicity Intuition Argument PI- Objects cannot coalesce with other objects to form something that in itself has consciousnesss because conscious beings are simple. P2- Nature, relation and environment of these multiple entities do not affect the simplicity intuition. P3- The nature, relation and environment of protophenomenal properties are not different in such a way that multiple entities possess consciousness. P4- Through avoiding the simplicity intuition, neutral monism could prove sound if a single protophenomenal property gives rise to phenomenal consciousness (explained below). Conclusion- Neutral monism is unsound except in the instance of P4.

(4) Objection to the Simplicity Intuition on Behalf of Neutral Monism There is one possible counter-example that can subvert the simple consciousness intuition when applied to neutral monism. The counter-example is if phenomenal experience is possessed by a simple construction. It is a possibility that there is a single unique quark in my brain, which is under the governance of protophenomenal feature. This single protophenomenal feature could give rise to my phenomenal experience. This single protophenomenal feature could also dictate my physical state. This evades the general simplicity intuition because it is a single, simple member, having the phenomenal experience. I object to this counter-example. I argue that the possibility of protophenomenal properties actually existing is in general absurd. I argue against neutral monism in whole and present an alternative solution. My solution states that it is more plausible that physical forces govern these subatomic particles. These physical forces which govern the particles do not possess any feature of consciousness. If all of these neutral particle properties are in fact just physical forces, then there is no room for a single protophenomenal property to govern the physical state or have phenomenal experience. I elaborate on this solution in section (6).

(5) Chalmers’ Faux Pas In his book The Conscious Mind David Chalmers accepts neutral monism. I would not choose this path. His primary view on these subatomic particles and their properties before accepting neutral monism is based on a very weak definition which I explain on the next page. He then goes to say that if one does not agree with his primary view, he accepts neutral monism as an alternative. I believe his primary position is even weaker then his accepting neutral monism as a fall back. He begins by accepting an ostensive definition of the fundamental particle’s properties (charge, spin, etc). He constructs his definitions of these properties on their observed actions, effects, and relations to other properties and objects. He accepts that the reductive explanation definition process is not necessary for the definition of these particle properties. Since we cannot know the intrinsic nature of these features, Chalmers would define the property charge as something similar to this. “To have charge is to do that (as he points to a quark). Charge is the feature that makes a particle act a certain way. X has positive charge if and only if X repels other positively charged particles and attracts negatively charged particles”. This is a terribly feeble definition. There is obviously more information needed to define a subatomic particle’s charge then its observed behavior. Many notable philosophers have argued against The Demise of Neutral Monism Due to the Simplicity Intuition the process of ostensive definition. In the interest of brevity I will not write on this. Chalmers then offers an alternative to his primary view of ostensive definition in understanding these particle properties, a charge’s intrinsic nature could be a protophenomenal state (neutral monism). I reject both of these views. I reject his primary theory because his definitions of these subatomic properties are feeble and do not adequately explain, “what it is to be one of these subatomic properties”. I reject his alternative view of accepting neutral monism for two reasons. The first reason is the simplicity intuition of conscious beings, which I have explained previously. The second reason for my rejecting Chalmers’ neutral monism is my solution of strictly physical forces governing elementary particles, which I explain in section (6).

(6) The Solution of Unknown Physical Force In my second argument against neutral monism I defend our temporary scientific knowledge gap. I believe that these properties of charge, spin, etc are strictly physical features and forces and we currently lack the technology to understand these features and forces. I believe that as particle acceleration technology continues to progress; one day these properties will be understood and explained with an intrinsic physical feature that is completely guided by physical laws. If these properties are of strictly physical nature, then there is no room for protophenomenal properties to govern the particles. If there is no room for protophenomenal properties to govern the particles, then these protophenomenal properties do not exist. If these protophenomenal properties do not exist, then neutral monism is false. I do not reject the possibility that these quarks and leptons could be true elementary particles. It is definitely possible that we have discovered the most fundamental things in existence. I am only proposing that the properties of these quarks and leptons (charge, spin, etc) which govern the nature of these particles are strictly physical forces. I do not believe that protophenomenal properties are hiding in our quarks the same way the boogey man hides in your closet at night. I think it is absurd to accept such a view. I am arguing that an elementary particle’s properties are governed strictly by physical laws and forces. Neutral monism exploits our current knowledge gap. The process of the “neutral property” governing the elementary particles is the same exact process as if the “neutral property” was just physical property. This protophenomenal feature is only different from my theorized physical force in that it claims to also give rise to experience. This is absurd. If I am correct, then protophenomenal property turns out to be strictly physical property. Neutral monism ends up being materialism because it has lost the feature which gives rise to phenomenal consciousness. Protophenomenal state was supposed to possess consciousness. We know that the phenomenal state does not necessarily logically supervene on the physical. If the protophenomenal is just physical, the argument crumbles into a back door for materialism. I have argued that neutral monism is false. The justification for this is in our simplicity intuition of phenomenal experience. I have also expressed the alternative solution that these “protophenomenal” properties are really physical features which have yet to be discovered by the high-energy physicists. The Large Hadron Collider at CERN will be once again operational this year (2009), and these questions will hopefully be answered sooner then we think. I believe that neutral monism is weak, and I believe that David Chalmers trotted down the wrong path when he accepted the neutral monism view. Neutral monism is a fallback position, reserved for those who cannot fully commit themselves to the more substantial theories of dualism or physicalism.

References Arete

Barnett, David. You are Simple, Forthcoming in The Waning of Materialism: New Essays, edited by George Bealer and Robert Koons

Barnett, David. The Simplicity Intuition and Its Hidden Influence on Philosophy of Mind. Noûs 42: 308-35 (2008).

Chalmers, David. (1996) The Conscious Mind’ In Search of a Fundamental Theory, Oxford: Oxford University Press.

Putnam, Hilary. (1967) The Nature of Mental States, in Readings in Philosophy of Psychology : 1980, edited by N. Block., Cambridge: Harvard University Press

Putnam, Hilary. (1975) Mind, Language and Reality, Cambridge University Press

Russell, Bertrand. (1921) The Analysis of Mind, London: George Allen and Unwin; New York: The Macmillan Company.

Russell, Bertrand. Neutral Monism, and Excerpt from Philosophy

Wittgenstein, Ludwig. Philosophical Investigations, Prentice Hall Publishing (1953).

For informative and illuminating conversation, I would like to thank Professor David Barnett and Professor Robert Rupert.