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Dualism

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Dualism

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Howard Robinson

Dualism

First published Tue Aug 19, 2003; substantive revision Thu Nov 3, 2011

This entry concerns dualism in the philosophy of mind. The term

‘dualism’ has a variety of uses in the history of thought. In general, the

idea is that, for some particular domain, there are two fundamental kinds

or categories of things or principles. In theology, for example a ‘dualist’ is

someone who believes that Good and Evil—or God and the Devil—are

independent and more or less equal forces in the world. Dualism contrasts

with monism, which is the theory that there is only one fundamental kind,

category of thing or principle; and, rather less commonly, with pluralism,

which is the view that there are many kinds or categories. In the

philosophy of mind, dualism is the theory that the mental and the physical

—or mind and body or mind and brain—are, in some sense, radically

different kinds of thing. Because common sense tells us that there are

physical bodies, and because there is intellectual pressure towards

producing a unified view of the world, one could say that materialist

monism is the ‘default option’. Discussion about dualism, therefore, tends

to start from the assumption of the reality of the physical world, and then

to consider arguments for why the mind cannot be treated as simply part

of that world.

1. The Mind-Body Problem and the History of Dualism

1.1 The Mind-Body Problem

1.2 The History of Dualism

2. Varieties of Dualism: Ontology

2.1 Predicate dualism

2.2 Property Dualism

2.3 Substance Dualism

3. Varieties of Dualism: Interaction

3.1 Interactionism

3.2 Epiphenomenalism

3.3 Parallelism

4. Arguments for Dualism

4.1 The Knowledge Argument Against Physicalism

4.2 The Argument from Predicate Dualism to Property Dualism

4.3 The Modal Argument

4.4 Arguments from Personal Identity

4.5 The Aristotelian Argument in a Modern Form

5. Problems for Dualism

5.1 The Queerness of the Mental

5.2 The Unity of the Mind

5.2.1 Unity and Bundle Dualism

5.2.2 Unity and Substance Dualism

Bibliography

Academic Tools

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Related Entries

1. The Mind-Body Problem and the History of

Dualism

1.1 The Mind-Body Problem

The mind-body problem is the problem: what is the relationship between

mind and body? Or alternatively: what is the relationship between mental

properties and physical properties?

Humans have (or seem to have) both physical properties and mental

properties. People have (or seem to have)the sort of properties attributed

in the physical sciences. These physical properties include size, weight,

shape, colour, motion through space and time, etc. But they also have (or

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seem to have) mental properties, which we do not attribute to typical

physical objects These properties involve consciousness (including

perceptual experience, emotional experience, and much else),

intentionality (including beliefs, desires, and much else), and they are

possessed by a subject or a self.

Physical properties are public, in the sense that they are, in principle,

equally observable by anyone. Some physical properties—like those of an

electron—are not directly observable at all, but they are equally available

to all, to the same degree, with scientific equipment and techniques. The

same is not true of mental properties. I may be able to tell that you are in

pain by your behaviour, but only you can feel it directly. Similarly, you

just know how something looks to you, and I can only surmise. Conscious

mental events are private to the subject, who has a privileged access to

them of a kind no-one has to the physical.

The mind-body problem concerns the relationship between these two sets

of properties. The mind-body problem breaks down into a number of

components.

1. The ontological question: what are mental states and what are

physical states? Is one class a subclass of the other, so that all mental

states are physical, or vice versa? Or are mental states and physical

states entirely distinct?

2. The causal question: do physical states influence mental states? Do

mental states influence physical states? If so, how?

Different aspects of the mind-body problem arise for different aspects of

the mental, such as consciousness, intentionality, the self.

3. The problem of consciousness: what is consciousness? How is it

related to the brain and the body?

4. The problem of intentionality: what is intentionality? How is it

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related to the brain and the body?

5. The problem of the self: what is the self? How is it related to the

brain and the body?

Other aspects of the mind-body problem arise for aspects of the physical.

For example:

6. The problem of embodiment: what is it for the mind to be housed in

a body? What is it for a body to belong to a particular subject?

The seemingly intractable nature of these problems have given rise to

many different philosophical views.

Materialist views say that, despite appearances to the contrary, mental

states are just physical states. Behaviourism, functionalism, mind-brain

identity theory and the computational theory of mind are examples of

how materialists attempt to explain how this can be so. The most common

factor in such theories is the attempt to explicate the nature of mind and

consciousness in terms of their ability to directly or indirectly modify

behaviour, but there are versions of materialism that try to tie the mental

to the physical without explicitly explaining the mental in terms of its

behaviour-modifying role. The latter are often grouped together under the

label ‘non-reductive physicalism’, though this label is itself rendered

elusive because of the controversial nature of the term ‘reduction’.

Idealist views say that physical states are really mental. This is because

the physical world is an empirical world and, as such, it is the

intersubjective product of our collective experience.

Dualist views (the subject of this entry) say that the mental and the

physical are both real and neither can be assimilated to the other. For the

various forms that dualism can take and the associated problems, see

below.

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4 Stanford Encyclopedia of Philosophy

In sum, we can say that there is a mind-body problem because both

consciousness and thought, broadly construed, seem very different from

anything physical and there is no convincing consensus on how to build a

satisfactorily unified picture of creatures possessed of both a mind and a

body.

Other entries which concern aspects of the mind-body problem include

(among many others): behaviorism, consciousness, eliminative

materialism, epiphenomenalism, functionalism, identity theory,

intentionality, mental causation, neutral monism, and physicalism.

1.2 History of dualism

In dualism, ‘mind’ is contrasted with ‘body’, but at different times,

different aspects of the mind have been the centre of attention. In the

classical and mediaeval periods, it was the intellect that was thought to be

most obviously resistant to a materialistic account: from Descartes on, the

main stumbling block to materialist monism was supposed to be

‘consciousness’, of which phenomenal consciousness or sensation came

to be considered as the paradigm instance.

The classical emphasis originates in Plato's Phaedo. Plato believed that

the true substances are not physical bodies, which are ephemeral, but the

eternal Forms of which bodies are imperfect copies. These Forms not

only make the world possible, they also make it intelligible, because they

perform the role of universals, or what Frege called ‘concepts'. It is their

connection with intelligibility that is relevant to the philosophy of mind.

Because Forms are the grounds of intelligibility, they are what the

intellect must grasp in the process of understanding. In Phaedo Plato

presents a variety of arguments for the immortality of the soul, but the

one that is relevant for our purposes is that the intellect is immaterial

because Forms are immaterial and intellect must have an affinity with the

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Forms it apprehends (78b4–84b8). This affinity is so strong that the soul

strives to leave the body in which it is imprisoned and to dwell in the

realm of Forms. It may take many reincarnations before this is achieved.

Plato's dualism is not, therefore, simply a doctrine in the philosophy of

mind, but an integral part of his whole metaphysics.

One problem with Plato's dualism was that, though he speaks of the soul

as imprisoned in the body, there is no clear account of what binds a

particular soul to a particular body. Their difference in nature makes the

union a mystery.

Aristotle did not believe in Platonic Forms, existing independently of

their instances. Aristotelian forms (the capital ‘F’ has disappeared with

their standing as autonomous entities) are the natures and properties of

things and exist embodied in those things. This enabled Aristotle to

explain the union of body and soul by saying that the soul is the form of

the body. This means that a particular person's soul is no more than his

nature as a human being. Because this seems to make the soul into a

property of the body, it led many interpreters, both ancient and modern, to

interpret his theory as materialistic. The interpretation of Aristotle's

philosophy of mind—and, indeed, of his whole doctrine of form—

remains as live an issue today as it was immediately after his death

(Robinson 1983 and 1991; Nussbaum 1984; Rorty and Nussbaum, eds,

1992). Nevertheless, the text makes it clear that Aristotle believed that the

intellect, though part of the soul, differs from other faculties in not having

a bodily organ. His argument for this constitutes a more tightly argued

case than Plato's for the immateriality of thought and, hence, for a kind of

dualism. He argued that the intellect must be immaterial because if it

were material it could not receive all forms. Just as the eye, because of its

particular physical nature, is sensitive to light but not to sound, and the

ear to sound and not to light, so, if the intellect were in a physical organ it

could be sensitive only to a restricted range of physical things; but this is

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not the case, for we can think about any kind of material object (De

Anima III,4; 429a10–b9). As it does not have a material organ, its activity

must be essentially immaterial.

It is common for modern Aristotelians, who otherwise have a high view

of Aristotle's relevance to modern philosophy, to treat this argument as

being of purely historical interest, and not essential to Aristotle's system

as a whole. They emphasize that he was not a ‘Cartesian’ dualist, because

the intellect is an aspect of the soul and the soul is the form of the body,

not a separate substance. Kenny (1989) argues that Aristotle's theory of

mind as form gives him an account similar to Ryle (1949), for it makes

the soul equivalent to the dispositions possessed by a living body. This

‘anti-Cartesian’ approach to Aristotle arguably ignores the fact that, for

Aristotle, the form is the substance.

These issues might seem to be of purely historical interest. But we shall

see in below, in section 4.5, that this is not so.

The identification of form and substance is a feature of Aristotle's system

that Aquinas effectively exploits in this context, identifying soul, intellect

and form, and treating them as a substance. (See, for example, Aquinas

(1912), Part I, questions 75 and 76.) But though the form (and, hence, the

intellect with which it is identical) are the substance of the human person,

they are not the person itself. Aquinas says that when one addresses

prayers to a saint—other than the Blessed Virgin Mary, who is believed

to retain her body in heaven and is, therefore, always a complete person—

one should say, not, for example, ‘Saint Peter pray for us', but ‘soul of

Saint Peter pray for us'. The soul, though an immaterial substance, is the

person only when united with its body. Without the body, those aspects of

its personal memory that depend on images (which are held to be

corporeal) will be lost.(See Aquinas (1912), Part I, question 89.)

The more modern versions of dualism have their origin in Descartes'

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Meditations, and in the debate that was consequent upon Descartes'

theory. Descartes was a substance dualist. He believed that there were

two kinds of substance: matter, of which the essential property is that it is

spatially extended; and mind, of which the essential property is that it

thinks. Descartes' conception of the relation between mind and body was

quite different from that held in the Aristotelian tradition. For Aristotle,

there is no exact science of matter. How matter behaves is essentially

affected by the form that is in it. You cannot combine just any matter with

any form—you cannot make a knife out of butter, nor a human being out

of paper—so the nature of the matter is a necessary condition for the

nature of the substance. But the nature of the substance does not follow

from the nature of its matter alone: there is no ‘bottom up’ account of

substances. Matter is a determinable made determinate by form. This was

how Aristotle thought that he was able to explain the connection of soul

to body: a particular soul exists as the organizing principle in a particular

parcel of matter.

The belief in the relative indeterminacy of matter is one reason for

Aristotle's rejection of atomism. If matter is atomic, then it is already a

collection of determinate objects in its own right, and it becomes natural

to regard the properties of macroscopic substances as mere summations of

the natures of the atoms.

Although, unlike most of his fashionable contemporaries and immediate

successors, Descartes was not an atomist, he was, like the others, a

mechanist about the properties of matter. Bodies are machines that work

according to their own laws. Except where there are minds interfering

with it, matter proceeds deterministically, in its own right. Where there

are minds requiring to influence bodies, they must work by ‘pulling

levers' in a piece of machinery that already has its own laws of operation.

This raises the question of where those ‘levers' are in the body. Descartes

opted for the pineal gland, mainly because it is not duplicated on both

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sides of the brain, so it is a candidate for having a unique, unifying

function.

The main uncertainty that faced Descartes and his contemporaries,

however, was not where interaction took place, but how two things so

different as thought and extension could interact at all. This would be

particularly mysterious if one had an impact view of causal interaction, as

would anyone influenced by atomism, for whom the paradigm of

causation is like two billiard balls cannoning off one another.

Various of Descartes' disciples, such as Arnold Geulincx and Nicholas

Malebranche, concluded that all mind-body interactions required the

direct intervention of God. The appropriate states of mind and body were

only the occasions for such intervention, not real causes. Now it would be

convenient to think that occasionalists held that all causation was natural

except for that between mind and body. In fact they generalized their

conclusion and treated all causation as directly dependent on God. Why

this was so, we cannot discuss here.

Descartes' conception of a dualism of substances came under attack from

the more radical empiricists, who found it difficult to attach sense to the

concept of substance at all. Locke, as a moderate empiricist, accepted that

there were both material and immaterial substances. Berkeley famously

rejected material substance, because he rejected all existence outside the

mind. In his early Notebooks, he toyed with the idea of rejecting

immaterial substance, because we could have no idea of it, and reducing

the self to a collection of the ‘ideas' that constituted its contents. Finally,

he decided that the self, conceived as something over and above the ideas

of which it was aware, was essential for an adequate understanding of the

human person. Although the self and its acts are not presented to

consciousness as objects of awareness, we are obliquely aware of them

simply by dint of being active subjects. Hume rejected such claims, and

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proclaimed the self to be nothing more than a concatenation of its

ephemeral contents.

In fact, Hume criticised the whole conception of substance for lacking in

empirical content: when you search for the owner of the properties that

make up a substance, you find nothing but further properties.

Consequently, the mind is, he claimed, nothing but a ‘bundle’ or ‘heap’ of

impressions and ideas—that is, of particular mental states or events,

without an owner. This position has been labelled bundle dualism, and it

is a special case of a general bundle theory of substance, according to

which objects in general are just organised collections of properties. The

problem for the Humean is to explain what binds the elements in the

bundle together. This is an issue for any kind of substance, but for

material bodies the solution seems fairly straightforward: the unity of a

physical bundle is constituted by some form of causal interaction between

the elements in the bundle. For the mind, mere causal connection is not

enough; some further relation of co-consciousness is required. We shall

see in 5.2.1 that it is problematic whether one can treat such a relation as

more primitive than the notion of belonging to a subject.

One should note the following about Hume's theory. His bundle theory is

a theory about the nature of the unity of the mind. As a theory about this

unity, it is not necessarily dualist. Parfit (1970, 1984) and Shoemaker

(1984, ch. 2), for example, accept it as physicalists. In general,

physicalists will accept it unless they wish to ascribe the unity to the

brain or the organism as a whole. Before the bundle theory can be dualist

one must accept property dualism, for more about which, see the next

section.

A crisis in the history of dualism came, however, with the growing

popularity of mechanism in science in the nineteenth century. According

to the mechanist, the world is, as it would now be expressed, ‘closed

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under physics’. This means that everything that happens follows from and

is in accord with the laws of physics. There is, therefore, no scope for

interference in the physical world by the mind in the way that

interactionism seems to require. According to the mechanist, the

conscious mind is an epiphenomenon (a notion given general currency by

T. H. Huxley 1893): that is, it is a by-product of the physical system

which has no influence back on it. In this way, the facts of consciousness

are acknowledged but the integrity of physical science is preserved.

However, many philosophers found it implausible to claim such things as

the following; the pain that I have when you hit me, the visual sensations

I have when I see the ferocious lion bearing down on me or the conscious

sense of understanding I have when I hear your argument—all have

nothing directly to do with the way I respond. It is very largely due to the

need to avoid this counterintuitiveness that we owe the concern of

twentieth century philosophy to devise a plausible form of materialist

monism. But, although dualism has been out of fashion in psychology

since the advent of behaviourism (Watson 1913) and in philosophy since

Ryle (1949), the argument is by no means over. Some distinguished

neurologists, such as Sherrington (1940) and Eccles (Popper and Eccles

1977) have continued to defend dualism as the only theory that can

preserve the data of consciousness. Amongst mainstream philosophers,

discontent with physicalism led to a modest revival of property dualism in

the last decade of the twentieth century. At least some of the reasons for

this should become clear below.

2. Varieties of Dualism: Ontology

There are various ways of dividing up kinds of dualism. One natural way

is in terms of what sorts of things one chooses to be dualistic about. The

most common categories lighted upon for these purposes are substance

and property, giving one substance dualism and property dualism. There

is, however, an important third category, namely predicate dualism. As

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this last is the weakest theory, in the sense that it claims least, I shall

begin by characterizing it.

2.1 Predicate dualism

Predicate dualism is the theory that psychological or mentalistic

predicates are (a) essential for a full description of the world and (b) are

not reducible to physicalistic predicates. For a mental predicate to be

reducible, there would be bridging laws connecting types of psychological

states to types of physical ones in such a way that the use of the mental

predicate carried no information that could not be expressed without it.

An example of what we believe to be a true type reduction outside

psychology is the case of water, where water is always H

O: something is

water if and only if it is H

O. If one were to replace the word ‘water’ by

‘H

O’, it is plausible to say that one could convey all the same

information. But the terms in many of the special sciences (that is, any

science except physics itself) are not reducible in this way. Not every

hurricane or every infectious disease, let alone every devaluation of the

currency or every coup d'etat has the same constitutive structure. These

states are defined more by what they do than by their composition or

structure. Their names are classified as functional terms rather than

natural kind terms. It goes with this that such kinds of state are multiply

realizable; that is, they may be constituted by different kinds of physical

structures under different circumstances. Because of this, unlike in the

case of water and H

O, one could not replace these terms by some more

basic physical description and still convey the same information. There is

no particular description, using the language of physics or chemistry, that

would do the work of the word ‘hurricane’, in the way that ‘H

O’ would

do the work of ‘water’. It is widely agreed that many, if not all,

psychological states are similarly irreducible, and so psychological

predicates are not reducible to physical descriptions and one has predicate

dualism. (The classic source for irreducibility in the special sciences in

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general is Fodor (1974), and for irreducibility in the philosophy of mind,

Davidson (1971).)

2.2 Property Dualism

Whereas predicate dualism says that there are two essentially different

kinds of predicates in our language, property dualism says that there are

two essentially different kinds of property out in the world. Property

dualism can be seen as a step stronger than predicate dualism. Although

the predicate ‘hurricane’ is not equivalent to any single description using

the language of physics, we believe that each individual hurricane is

nothing but a collection of physical atoms behaving in a certain way: one

need have no more than the physical atoms, with their normal physical

properties, following normal physical laws, for there to be a hurricane.

One might say that we need more than the language of physics to

describe and explain the weather, but we do not need more than its

ontology. There is token identity between each individual hurricane and a

mass of atoms, even if there is no type identity between hurricanes as

kinds and some particular structure of atoms as a kind. Genuine property

dualism occurs when, even at the individual level, the ontology of physics

is not sufficient to constitute what is there. The irreducible language is not

just another way of describing what there is, it requires that there be

something more there than was allowed for in the initial ontology. Until

the early part of the twentieth century, it was common to think that

biological phenomena (‘life’) required property dualism (an irreducible

‘vital force’), but nowadays the special physical sciences other than

psychology are generally thought to involve only predicate dualism. In

the case of mind, property dualism is defended by those who argue that

the qualitative nature of consciousness is not merely another way of

categorizing states of the brain or of behaviour, but a genuinely emergent

phenomenon.

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2.3 Substance Dualism

There are two important concepts deployed in this notion. One is that of

substance, the other is the dualism of these substances. A substance is

characterized by its properties, but, according to those who believe in

substances, it is more than the collection of the properties it possesses, it

is the thing which possesses them. So the mind is not just a collection of

thoughts, but is that which thinks, an immaterial substance over and above

its immaterial states. Properties are the properties of objects. If one is a

property dualist, one may wonder what kinds of objects possess the

irreducible or immaterial properties in which one believes. One can use a

neutral expression and attribute them to persons, but, until one has an

account of person, this is not explanatory. One might attribute them to

human beings qua animals, or to the brains of these animals. Then one

will be holding that these immaterial properties are possessed by what is

otherwise a purely material thing. But one may also think that not only

mental states are immaterial, but that the subject that possesses them must

also be immaterial. Then one will be a dualist about that to which mental

states and properties belong as well about the properties themselves. Now

one might try to think of these subjects as just bundles of the immaterial

states. This is Hume's view. But if one thinks that the owner of these

states is something quite over and above the states themselves, and is

immaterial, as they are, one will be a substance dualist.

Substance dualism is also often dubbed ‘Cartesian dualism’, but some

substance dualists are keen to distinguish their theories from Descartes's.

E. J. Lowe, for example, is a substance dualist, in the following sense. He

holds that a normal human being involves two substances, one a body and

the other a person. The latter is not, however, a purely mental substance

that can be defined in terms of thought or consciousness alone, as

Descartes claimed. But persons and their bodies have different identity

conditions and are both substances, so there are two substances essentially

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involved in a human being, hence this is a form of substances dualism.

Lowe (2006) claims that his theory is close to P. F. Strawson's (1959),

whilst admitting that Strawson would not have called it substance

dualism.

3. Varieties of Dualism: Interaction

If mind and body are different realms, in the way required by either

property or substance dualism, then there arises the question of how they

are related. Common sense tells us that they interact: thoughts and

feelings are at least sometimes caused by bodily events and at least

sometimes themselves give rise to bodily responses. I shall now consider

briefly the problems for interactionism, and its main rivals,

epiphenomenalism and parallelism.

3.1 Interactionism

Interactionism is the view that mind and body—or mental events and

physical events—causally influence each other. That this is so is one of

our common-sense beliefs, because it appears to be a feature of everyday

experience. The physical world influences my experience through my

senses, and I often react behaviourally to those experiences. My thinking,

too, influences my speech and my actions. There is, therefore, a massive

natural prejudice in favour of interactionism. It has been claimed,

however, that it faces serious problems (some of which were anticipated

in section 1).

The simplest objection to interaction is that, in so far as mental properties,

states or substances are of radically different kinds from each other, they

lack that communality necessary for interaction. It is generally agreed

that, in its most naive form, this objection to interactionism rests on a

‘billiard ball’ picture of causation: if all causation is by impact, how can

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the material and the immaterial impact upon each other? But if causation

is either by a more ethereal force or energy or only a matter of constant

conjunction, there would appear to be no problem in principle with the

idea of interaction of mind and body.

Even if there is no objection in principle, there appears to be a conflict

between interactionism and some basic principles of physical science. For

example, if causal power was flowing in and out of the physical system,

energy would not be conserved, and the conservation of energy is a

fundamental scientific law. Various responses have been made to this.

One suggestion is that it might be possible for mind to influence the

distribution of energy, without altering its quantity. (See Averill and

Keating 1981). Another response is to challenge the relevance of the

conservation principle in this context. The conservation principle states

that ‘in a causally isolated system the total amount of energy will remain

constant’. Whereas ‘[t]he interactionist denies…that the human body is an

isolated system’, so the principle is irrelevant (Larmer (1986), 282: this

article presents a good brief survey of the options).

Robins Collins (2011) has claimed that the appeal to conservation by

opponents of interactionism is something of a red herring because

conservation principles are not ubiquitous in physics. He argues that

energy is not conserved in general relativity, in quantum theory, or in the

universe taken as a whole. Why then, should we insist on it in mind-brain

interaction?

Most discussion of interactionism takes place in the context of the

assumption that it is incompatible with the world's being ‘closed under

physics’. This is a very natural assumption, but it is not justified if causal

overdetermination of behaviour is possible. There could then be a

complete physical cause of behaviour, and a mental one. The strongest

intuitive objection against overdetermination is clearly stated by Mills

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(1996: 112), who is himself a defender of overdetermination.

For X to be a cause of Y, X must contribute something to Y. The only way

a purely mental event could contribute to a purely physical one would be

to contribute some feature not already determined by a purely physical

event. But if physical closure is true, there is no feature of the purely

physical effect that is not contributed by the purely physical cause. Hence

interactionism violates physical closure after all.

Mills says that this argument is invalid, because a physical event can have

features not explained by the event which is its sufficient cause. For

example, “the rock's hitting the window is causally sufficient for the

window's breaking, and the window's breaking has the feature of being

the third window-breaking in the house this year; but the facts about prior

window-breakings, rather than the rock's hitting the window, are what

cause this window-breaking to have this feature.”

The opponent of overdetermination could perhaps reply that his principle

applies, not to every feature of events, but to a subgroup—say, intrinsic

features, not merely relational or comparative ones. It is this kind of

feature that the mental event would have to cause, but physical closure

leaves no room for this. These matters are still controversial.

The problem with closure of physics may be radically altered if physical

laws are indeterministic, as quantum theory seems to assert. If physical

laws are deterministic, then any interference from outside would lead to a

breach of those laws. But if they are indeterministic, might not

interference produce a result that has a probability greater than zero, and

so be consistent with the laws? This way, one might have interaction yet

preserve a kind of nomological closure, in the sense that no laws are

infringed. Because it involves assessing the significance and

consequences of quantum theory, this is a difficult matter for the non-

physicist to assess. Some argue that indeterminacy manifests itself only

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on the subatomic level, being cancelled out by the time one reaches even

very tiny macroscopic objects: and human behaviour is a macroscopic

phenomenon. Others argue that the structure of the brain is so finely

tuned that minute variations could have macroscopic effects, rather in the

way that, according to ‘chaos theory’, the flapping of a butterfly's wings

in China might affect the weather in New York. (For discussion of this,

see Eccles (1980), (1987), and Popper and Eccles (1977).) Still others

argue that quantum indeterminacy manifests itself directly at a high level,

when acts of observation collapse the wave function, suggesting that the

mind may play a direct role in affecting the state of the world (Hodgson

1988; Stapp 1993).

3.2 Epiphenomenalism

If the reality of property dualism is not to be denied, but the problem of

how the immaterial is to affect the material is to be avoided, then

epiphenomenalism may seem to be the answer. According to this theory,

mental events are caused by physical events, but have no causal influence

on the physical. I have introduced this theory as if its point were to avoid

the problem of how two different categories of thing might interact. In

fact, it is, at best, an incomplete solution to this problem. If it is

mysterious how the non-physical can have it in its nature to influence the

physical, it ought to be equally mysterious how the physical can have it in

its nature to produce something non-physical. But that this latter is what

occurs is an essential claim of epiphenomenalism. (For development of

this point, see Green (2003), 149–51). In fact, epiphenomenalism is more

effective as a way of saving the autonomy of the physical (the world as

‘closed under physics') than as a contribution to avoiding the need for the

physical and non-physical to have causal commerce.

There are at least three serious problems for epiphenomenalism. First, as I

indicated in section 1, it is profoundly counterintuitive. What could be

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more apparent than that it is the pain that I feel that makes me cry, or the

visual experience of the boulder rolling towards me that makes me run

away? At least one can say that epiphenomenalism is a fall-back position:

it tends to be adopted because other options are held to be unacceptable.

The second problem is that, if mental states do nothing, there is no reason

why they should have evolved. This objection ties in with the first: the

intuition there was that conscious states clearly modify our behaviour in

certain ways, such as avoiding danger, and it is plain that they are very

useful from an evolutionary perspective.

Frank Jackson (1982) replies to this objection by saying that it is the brain

state associated with pain that evolves for this reason: the sensation is a

by-product. Evolution is full of useless or even harmful by-products. For

example, polar bears have evolved thick coats to keep them warm, even

though this has the damaging side effect that they are heavy to carry.

Jackson's point is true in general, but does not seem to apply very happily

to the case of mind. The heaviness of the polar bear's coat follows

directly from those properties and laws which make it warm: one could

not, in any simple way, have one without the other. But with mental

states, dualistically conceived, the situation is quite the opposite. The laws

of physical nature which, the mechanist says, make brain states cause

behaviour, in no way explain why brain states should give rise to

conscious ones. The laws linking mind and brain are what Feigl (1958)

calls nomological danglers, that is, brute facts added onto the body of

integrated physical law. Why there should have been by-products of that

kind seems to have no evolutionary explanation.

The third problem concerns the rationality of belief in epiphenomenalism,

via its effect on the problem of other minds. It is natural to say that I

know that I have mental states because I experience them directly. But

how can I justify my belief that others have them? The simple version of

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the ‘argument from analogy’ says that I can extrapolate from my own

case. I know that certain of my mental states are correlated with certain

pieces of behaviour, and so I infer that similar behaviour in others is also

accompanied by similar mental states. Many hold that this is a weak

argument because it is induction from one instance, namely, my own. The

argument is stronger if it is not a simple induction but an ‘argument to the

best explanation’. I seem to know from my own case that mental events

can be the explanation of behaviour, and I know of no other candidate

explanation for typical human behaviour, so I postulate the same

explanation for the behaviour of others. But if epiphenomenalism is true,

my mental states do not explain my behaviour and there is a physical

explanation for the behaviour of others. It is explanatorily redundant to

postulate such states for others. I know, by introspection, that I have them,

but is it not just as likely that I alone am subject to this quirk of nature,

rather than that everyone is?

For more detailed treatment and further reading on this topic, see the

entry epiphenomenalism.

3.3 Parallelism

The epiphenomenalist wishes to preserve the integrity of physical science

and the physical world, and appends those mental features that he cannot

reduce. The parallelist preserves both realms intact, but denies all causal

interaction between them. They run in harmony with each other, but not

because their mutual influence keeps each other in line. That they should

behave as if they were interacting would seem to be a bizarre coincidence.

This is why parallelism has tended to be adopted only by those—like

Leibniz—who believe in a pre-established harmony, set in place by God.

The progression of thought can be seen as follows. Descartes believes in a

more or less natural form of interaction between immaterial mind and

material body. Malebranche thought that this was impossible naturally,

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and so required God to intervene specifically on each occasion on which

interaction was required. Leibniz decided that God might as well set

things up so that they always behaved as if they were interacting, without

particular intervention being required. Outside such a theistic framework,

the theory is incredible. Even within such a framework, one might well

sympathise with Berkeley's instinct that once genuine interaction is ruled

out one is best advised to allow that God creates the physical world

directly, within the mental realm itself, as a construct out of experience.

4. Arguments for Dualism

4.1 The Knowledge Argument Against Physicalism

One category of arguments for dualism is constituted by the standard

objections against physicalism. Prime examples are those based on the

existence of qualia, the most important of which is the so-called

‘knowledge argument’. Because this argument has its own entry (see the

entry qualia: the knowledge argument), I shall deal relatively briefly with

it here. One should bear in mind, however, that all arguments against

physicalism are also arguments for the irreducible and hence immaterial

nature of the mind and, given the existence of the material world, are thus

arguments for dualism.

The knowledge argument asks us to imagine a future scientist who has

lacked a certain sensory modality from birth, but who has acquired a

perfect scientific understanding of how this modality operates in others.

This scientist—call him Harpo—may have been born stone deaf, but

become the world's greatest expert on the machinery of hearing: he knows

everything that there is to know within the range of the physical and

behavioural sciences about hearing. Suppose that Harpo, thanks to

developments in neurosurgery, has an operation which finally enables him

to hear. It is suggested that he will then learn something he did not know

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before, which can be expressed as what it is like to hear, or the qualitative

or phenomenal nature of sound. These qualitative features of experience

are generally referred to as qualia. If Harpo learns something new, he did

not know everything before. He knew all the physical facts before. So

what he learns on coming to hear—the facts about the nature of

experience or the nature of qualia—are non-physical. This establishes at

least a state or property dualism. (See Jackson 1982; Robinson 1982.)

There are at least two lines of response to this popular but controversial

argument. First is the ‘ability’ response. According to this, Harpo does not

acquire any new factual knowledge, only ‘knowledge how’, in the form of

the ability to respond directly to sounds, which he could not do before.

This essentially behaviouristic account is exactly what the intuition

behind the argument is meant to overthrow. Putting ourselves in Harpo's

position, it is meant to be obvious that what he acquires is knowledge of

what something is like, not just how to do something. Such appeals to

intuition are always, of course, open to denial by those who claim not to

share the intuition. Some ability theorists seem to blur the distinction

between knowing what something is like and knowing how to do

something, by saying that the ability Harpo acquires is to imagine or

remember the nature of sound. In this case, what he acquires the ability to

do involves the representation to himself of what the thing is like. But this

conception of representing to oneself, especially in the form of

imagination, seems sufficiently close to producing in oneself something

very like a sensory experience that it only defers the problem: until one

has a physicalist gloss on what constitutes such representations as those

involved in conscious memory and imagination, no progress has been

made.

The other line of response is to argue that, although Harpo's new

knowledge is factual, it is not knowledge of a new fact. Rather, it is new

way of grasping something that he already knew. He does not realise this,

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because the concepts employed to capture experience (such as ‘looks red’

or ‘sounds C-sharp’) are similar to demonstratives, and demonstrative

concepts lack the kind of descriptive content that allow one to infer what

they express from other pieces of information that one may already

possess. A total scientific knowledge of the world would not enable you

to say which time was ‘now’ or which place was ‘here’. Demonstrative

concepts pick something out without saying anything extra about it.

Similarly, the scientific knowledge that Harpo originally possessed did

not enable him to anticipate what it would be like to re-express some

parts of that knowledge using the demonstrative concepts that only

experience can give one. The knowledge, therefore, appears to be

genuinely new, whereas only the mode of conceiving it is novel.

Proponents of the epistemic argument respond that it is problematic to

maintain both that the qualitative nature of experience can be genuinely

novel, and that the quality itself be the same as some property already

grasped scientifically: does not the experience's phenomenal nature, which

the demonstrative concepts capture, constitute a property in its own right?

Another way to put this is to say that phenomenal concepts are not pure

demonstratives, like ‘here’ and ‘now’, or ‘this’ and ‘that’, because they do

capture a genuine qualitative content. Furthermore, experiencing does not

seem to consist simply in exercising a particular kind of concept,

demonstrative or not. When Harpo has his new form of experience, he

does not simply exercise a new concept; he also grasps something new—

the phenomenal quality—with that concept. How decisive these

considerations are, remains controversial.

4.2 The Argument from Predicate Dualism to Property Dualism

I said above that predicate dualism might seem to have no ontological

consequences, because it is concerned only with the different way things

can be described within the contexts of the different sciences, not with

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any real difference in the things themselves. This, however, can be

disputed.

The argument from predicate to property dualism moves in two steps,

both controversial. The first claims that the irreducible special sciences,

which are the sources of irreducible predicates, are not wholly objective

in the way that physics is, but depend for their subject matter upon

interest-relative perspectives on the world. This means that they, and the

predicates special to them, depend on the existence of minds and mental

states, for only minds have interest-relative perspectives. The second

claim is that psychology—the science of the mental—is itself an

irreducible special science, and so it, too, presupposes the existence of the

mental. Mental predicates therefore presuppose the mentality that creates

them: mentality cannot consist simply in the applicability of the

predicates themselves.

First, let us consider the claim that the special sciences are not fully

objective, but are interest-relative.

No-one would deny, of course, that the very same subject matter or ‘hunk

of reality’ can be described in irreducibly different ways and it still be just

that subject matter or piece of reality. A mass of matter could be

characterized as a hurricane, or as a collection of chemical elements, or as

mass of sub-atomic particles, and there be only the one mass of matter.

But such different explanatory frameworks seem to presuppose different

perspectives on that subject matter.

This is where basic physics, and perhaps those sciences reducible to basic

physics, differ from irreducible special sciences. On a realist construal,

the completed physics cuts physical reality up at its ultimate joints: any

special science which is nomically strictly reducible to physics also, in

virtue of this reduction, it could be argued, cuts reality at its joints, but

not at its minutest ones. If scientific realism is true, a completed physics

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will tell one how the world is, independently of any special interest or

concern: it is just how the world is. It would seem that, by contrast, a

science which is not nomically reducible to physics does not take its

legitimation from the underlying reality in this direct way. Rather, such a

science is formed from the collaboration between, on the one hand,

objective similarities in the world and, on the other, perspectives and

interests of those who devise the science. The concept of hurricane is

brought to bear from the perspective of creatures concerned about the

weather. Creatures totally indifferent to the weather would have no reason

to take the real patterns of phenomena that hurricanes share as

constituting a single kind of thing. With the irreducible special sciences,

there is an issue of salience , which involves a subjective component: a

selection of phenomena with a certain teleology in mind is required

before their structures or patterns are reified. The entities of metereology

or biology are, in this respect, rather like Gestalt phenomena.

Even accepting this, why might it be thought that the perspectivality of

the special sciences leads to a genuine property dualism in the philosophy

of mind? It might seem to do so for the following reason. Having a

perspective on the world, perceptual or intellectual, is a psychological

state. So the irreducible special sciences presuppose the existence of

mind. If one is to avoid an ontological dualism, the mind that has this

perspective must be part of the physical reality on which it has its

perspective. But psychology, it seems to be almost universally agreed, is

one of those special sciences that is not reducible to physics, so if its

subject matter is to be physical, it itself presupposes a perspective and,

hence, the existence of a mind to see matter as psychological. If this mind

is physical and irreducible, it presupposes mind to see it as such. We

seem to be in a vicious circle or regress.

We can now understand the motivation for full-blown reduction. A true

basic physics represents the world as it is in itself, and if the special

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sciences were reducible, then the existence of their ontologies would

make sense as expressions of the physical, not just as ways of seeing or

interpreting it. They could be understood ‘from the bottom up’, not from

top down. The irreducibility of the special sciences creates no problem for

the dualist, who sees the explanatory endeavor of the physical sciences as

something carried on from a perspective conceptually outside of the

physical world. Nor need this worry a physicalist, if he can reduce

psychology, for then he could understand ‘from the bottom up’ the acts

(with their internal, intentional contents) which created the irreducible

ontologies of the other sciences. But psychology is one of the least likely

of sciences to be reduced. If psychology cannot be reduced, this line of

reasoning leads to real emergence for mental acts and hence to a real

dualism for the properties those acts instantiate (Robinson 2003).

4.3 The Modal Argument

There is an argument, which has roots in Descartes (Meditation VI),

which is a modal argument for dualism. One might put it as follows:

1. It is imaginable that one's mind might exist without one's body.

therefore

2. It is conceivable that one's mind might exist without one's body.

therefore

3. It is possible one's mind might exist without one's body.

therefore

4. One's mind is a different entity from one's body.

The rationale of the argument is a move from imaginability to real

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possibility. I include (2) because the notion of conceivability has one foot

in the psychological camp, like imaginability, and one in the camp of pure

logical possibility and therefore helps in the transition from one to the

other.

This argument should be distinguished from a similar ‘conceivability’

argument, often known as the ‘zombie hypothesis’, which claims the

imaginability and possibility of my body (or, in some forms, a body

physically just like it) existing without there being any conscious states

associated with it. (See, for example, Chalmers (1996), 94–9.) This latter

argument, if sound, would show that conscious states were something

over and above physical states. It is a different argument because the

hypothesis that the unaltered body could exist without the mind is not the

same as the suggestion that the mind might continue to exist without the

body, nor are they trivially equivalent. The zombie argument establishes

only property dualism and a property dualist might think disembodied

existence inconceivable—for example, if he thought the identity of a

mind through time depended on its relation to a body (e.g., Penelhum

1970).

Before Kripke (1972/80), the first challenge to such an argument would

have concerned the move from (3) to (4). When philosophers generally

believed in contingent identity, that move seemed to them invalid. But

nowadays that inference is generally accepted and the issue concerns the

relation between imaginability and possibility. No-one would nowadays

identify the two (except, perhaps, for certain quasi-realists and anti-

realists), but the view that imaginability is a solid test for possibility has

been strongly defended. W. D. Hart ((1994), 266), for example, argues

that no clear example has been produced such that “one can imagine that p

(and tell less imaginative folk a story that enables them to imagine that p)

plus a good argument that it is impossible that p. No such

counterexamples have been forthcoming…” This claim is at least

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contentious. There seem to be good arguments that time-travel is

incoherent, but every episode of Star-Trek or Doctor Who shows how one

can imagine what it might be like were it possible.

It is worth relating the appeal to possibility in this argument to that

involved in the more modest, anti-physicalist, zombie argument. The

possibility of this hypothesis is also challenged, but all that is necessary

for a zombie to be possible is that all and only the things that the physical

sciences say about the body be true of such a creature. As the concepts

involved in such sciences—e.g., neuron, cell, muscle—seem to make no

reference, explicit or implicit, to their association with consciousness, and

are defined in purely physical terms in the relevant science texts, there is

a very powerful prima facie case for thinking that something could meet

the condition of being just like them and lack any connection with

consciousness. There is no parallel clear, uncontroversial and regimented

account of mental concepts as a whole that fails to invoke, explicitly or

implicitly, physical (e.g., behavioural) states.

For an analytical behaviourist the appeal to imaginability made in the

argument fails, not because imagination is not a reliable guide to

possibility, but because we cannot imagine such a thing, as it is a priori

impossible. The impossibility of disembodiment is rather like that of time

travel, because it is demonstrable a priori, though only by arguments that

are controversial. The argument can only get under way for those

philosophers who accept that the issue cannot be settled a priori, so the

possibility of the disembodiment that we can imagine is still prima facie

open.

A major rationale of those who think that imagination is not a safe

indication of possibility, even when such possibility is not eliminable a

priori, is that we can imagine that a posteriori necessities might be false—

for example, that Hesperus might not be identical to Phosphorus. But if

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Kripke is correct, that is not a real possibility. Another way of putting this

point is that there are many epistemic possibilities which are imaginable

because they are epistemic possibilities, but which are not real

possibilities. Richard Swinburne (1997, New Appendix C), whilst

accepting this argument in general, has interesting reasons for thinking

that it cannot apply in the mind-body case. He argues that in cases that

involve a posteriori necessities, such as those identities that need

discovering, it is because we identify those entities only by their

‘stereotypes’ (that is, by their superficial features observable by the

layman) that we can be wrong about their essences. In the case of our

experience of ourselves this is not true.

Now it is true that the essence of Hesperus cannot be discovered by a

mere thought experiment. That is because what makes Hesperus Hesperus

is not the stereotype, but what underlies it. But it does not follow that no

one can ever have access to the essence of a substance, but must always

rely for identification on a fallible stereotype. One might think that for the

person him or herself, while what makes that person that person underlies

what is observable to others, it does not underlie what is experienceable

by that person, but is given directly in their own self-awareness.

This is a very appealing Cartesian intuition: my identity as the thinking

thing that I am is revealed to me in consciousness, it is not something

beyond the veil of consciousness. Now it could be replied to this that

though I do access myself as a conscious subject, so classifying myself is

rather like considering myself qua cyclist. Just as I might never have been

a cyclist, I might never have been conscious, if things had gone wrong in

my very early life. I am the organism, the animal, which might not have

developed to the point of consciousness, and that essence as animal is not

revealed to me just by introspection.

But there are vital differences between these cases. A cyclist is explicitly

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presented as a human being (or creature of some other animal species)

cycling: there is no temptation to think of a cyclist as a basic kind of thing

in its own right. Consciousness is not presented as a property of

something, but as the subject itself. Swinburne's claim that when we refer

to ourselves we are referring to something we think we are directly aware

of and not to ‘something we know not what’ that underlies our experience

seemingly ‘of ourselves’ has powerful intuitive appeal and could only be

overthrown by very forceful arguments. Yet, even if we are not referring

primarily to a substrate, but to what is revealed in consciousness, could it

not still be the case that there is a necessity stronger than causal

connecting this consciousness to something physical? To consider this

further we must investigate what the limits are of the possible analogy

between cases of the water-H

O kind, and the mind-body relation.

We start from the analogy between the water stereotype—how water

presents itself—and how consciousness is given first-personally to the

subject. It is plausible to claim that something like water could exist

without being H

O, but hardly that it could exist without some underlying

nature. There is, however, no reason to deny that this underlying nature

could be homogenous with its manifest nature: that is, it would seem to be

possible that there is a world in which the water-like stuff is an element,

as the ancients thought, and is water-like all the way down. The claim of

the proponents of the dualist argument is that this latter kind of situation

can be known to be true a priori in the case of the mind: that is, one can

tell by introspection that it is not more-than-causally dependent on

something of a radically different nature, such as a brain or body. What

grounds might one have for thinking that one could tell that a priori?

The only general argument that seem to be available for this would be the

principle that, for any two levels of discourse, A and B, they are more-

than-causally connected only if one entails the other a priori. And the

argument for accepting this principle would be that the relatively

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uncontroversial cases of a posteriori necessary connections are in fact

cases in which one can argue a priori from facts about the microstructure

to the manifest facts. In the case of water, for example, it would be

claimed that it follows a priori that if there were something with the

properties attributed to H

O by chemistry on a micro level, then that thing

would possess waterish properties on a macro level. What is established a

posteriori is that it is in fact H

O that underlies and explains the waterish

properties round here, not something else: the sufficiency of the base—

were it to obtain—to explain the phenomena, can be deduced a priori

from the supposed nature of the base. This is, in effect, the argument that

Chalmers uses to defend the zombie hypothesis. The suggestion is that the

whole category of a posteriori more-than-causally necessary connections

(often identified as a separate category of metaphysical necessity) comes

to no more than this. If we accept that this is the correct account of a

posteriori necessities, and also deny the analytically reductionist theories

that would be necessary for a priori connections between mind and body,

as conceived, for example, by the behaviourist or the functionalist, does it

follow that we can tell a priori that consciousness is not more-than-

causally dependent on the body?

It is helpful in considering this question to employ a distinction like

Berkeley's between ideas and notions. Ideas are the objects of our mental

acts, and they capture transparently—‘by way of image or likeness'

(Principles, sect. 27)—that of which they are the ideas. The self and its

faculties are not the objects of our mental acts, but are captured only

obliquely in the performance of its acts, and of these Berkeley says we

have notions, meaning by this that what we capture of the nature of the

dynamic agent does not seem to have the same transparency as what we

capture as the normal objects of the agent's mental acts. It is not necessary

to become involved in Berkeley's metaphysics in general to feel the force

of the claim that the contents and internal objects of our mental acts are

grasped with a lucidity that exceeds that of our grasp of the agent and the

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acts per se. Because of this, notions of the self perhaps have a ‘thickness’

and are permanently contestable: there seems always to be room for more

dispute as to what is involved in that concept. (Though we shall see later,

in 5.2.2, that there is a ‘non-thick’ way of taking the Berkeleyan concept

of a notion.)

Because ‘thickness’ always leaves room for dispute, this is one of those

cases in philosophy in which one is at the mercy of the arguments

philosophers happen to think up. The conceivability argument creates a

prima facie case for thinking that mind has no more than causal

ontological dependence on the body. Let us assume that one rejects

analytical (behaviourist or functionalist) accounts of mental predicates.

Then the above arguments show that any necessary dependence of mind

on body does not follow the model that applies in other scientific cases.

This does not show that there may not be other reasons for believing in

such dependence, for so many of the concepts in the area are still

contested. For example, it might be argued that identity through time

requires the kind of spatial existence that only body can give: or that the

causal continuity required by a stream of consciousness cannot be a

property of mere phenomena. All these might be put forward as ways of

filling out those aspects of our understanding of the self that are only

obliquely, not transparently, presented in self-awareness. The dualist must

respond to any claim as it arises: the conceivability argument does not

pre-empt them.

4.4 Arguments from Personal Identity

There is a long tradition, dating at least from Reid (1785/1969), for

arguing that the identity of persons over time is not a matter of

convention or degree in the way that the identity of other (complex)

substances is and that this shows that the self is a different kind of entity

from any physical body. Criticism of these arguments and of the intuitions

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on which they rest, running from Hume to Parfit (1970: 1984), have left

us with an inconclusive clash of intuitions. The argument under

consideration and which, possibly, has its first statement in Madell

(1981), does not concern identity through time, but the consequences for

identity of certain counterfactuals concerning origin. It can, perhaps,

therefore, break the stalemate which faces the debate over diachronic

identity. The claim is that the broadly conventionalist ways which are

used to deal with problem cases through time for both persons and

material objects, and which can also be employed in cases of

counterfactuals concerning origin for bodies, cannot be used for similar

counterfactuals concerning persons or minds.

Concerning ordinary physical objects, it is easy to imagine counterfactual

cases where questions of identity become problematic. Take the example

of a particular table. We can scale counterfactual suggestions as follows:

i. This table might have been made of ice.

ii. This table might have been made of a different sort of wood.

iii. This table might have been made of 95% of the wood it was made of

and 5% of some other wood.

The first suggestion would normally be rejected as clearly false, but there

will come a point along the spectrum illustrated by (i) and (iii) and

towards (iii) where the question of whether the hypothesised table would

be the same as the one that actually exists have no obvious answer. It

seems that the question of whether it ‘really’ is the same one has no clear

meaning: it is of, say, 75% the same matter and of 25% different matter;

these are the only genuine facts in the case; the question of numerical

identity can be decided in any convenient fashion, or left unresolved.

There will thus be a penumbra of counterfactual cases where the question

of whether two things would be the same is not a matter of fact.

Let us now apply this thought to conscious subjects. Suppose that a given

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human individual had had origins different from those which he in fact

had such that whether that difference affected who he was was not

obvious to intuition. What would count as such a case might be a matter

of controversy, but there must be one. Perhaps it is unclear whether, if

there had been a counterpart to Jones' body from the same egg but a

different though genetically identical sperm from the same father, the

person there embodied would have been Jones. Some philosophers might

regard it as obvious that sameness of sperm is essential to the identity of a

human body and to personal identity. In that case imagine a counterpart

sperm in which some of the molecules in the sperm are different; would

that be the same sperm? If one pursues the matter far enough there will be

indeterminacy which will infect that of the resulting body. There must

therefore be some difference such that neither natural language nor

intuition tells us whether the difference alters the identity of the human

body; a point, that is, where the question of whether we have the same

body is not a matter of fact.

How one is to describe these cases is, in some respects, a matter of

controversy. Some philosophers think one can talk of vague identity or

partial identity. Others think that such expressions are nonsensical. There

is no space to discuss this issue here. It is enough to assume, however,

that questions of how one is allowed to use the concept of identity effect

only the care with which one should characterize these cases, not any

substantive matter of fact. There are cases of substantial overlap of

constitution in which that fact is the only bedrock fact in the case: there is

no further fact about whether they are ‘really’ the same object. If there

were, then there would have to be a haecceitas or thisness belonging to

and individuating each complex physical object, and this I am assuming to

be implausible if not unintelligible. (More about the conditions under

which haecceitas can make sense will be found below.)

One might plausibly claim that no similar overlap of constitution can be

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applied to the counterfactual identity of minds. In Geoffrey Madell's

(1981) words:

Why is this so? Imagine the case where we are not sure whether it would

have been Jones' body—and, hence, Jones—that would have been created

by the slightly modified sperm and the same egg. Can we say, as we

would for an object with no consciousness, that the story something the

same, something different is the whole story: that overlap of constitution

is all there is to it? For the Jones body as such, this approach would do as

well as for any other physical object. But suppose Jones, in reflective

mood, asks himself ‘if that had happened, would I have existed?’ There

are at least three answers he might give to himself. (i) I either would or

would not, but I cannot tell. (ii) There is no fact of the matter whether I

would or would not have existed: it is just a mis-posed question. (iii) In

some ways, or to some degree, I would have, and in some ways, or to

some degree, I would not. The creature who would have existed would

have had a kind of overlap of psychic constitution with me.

The third answer parallels the response we would give in the case of

bodies. But as an account of the subjective situation, it is arguable that

this makes no sense. Call the creature that would have emerged from the

slightly modified sperm, ‘Jones2’. Is the overlap suggestion that, just as,

say 85% of Jones2's original body would have been identical with Jones',

about 85% of his psychic life would have been Jones'? That it would have

been like Jones'—indeed that Jones2 might have had a psychic life 100%

like Jones'—makes perfect sense, but that he might have been to that

degree, the same psyche—that Jones ‘85% existed’ —arguably makes no

But while my present body can thus have its partial counterpart in

some possible world, my present consciousness cannot. Any

present state of consciousness that I can imagine either is or is not

mine. There is no question of degree here. (91)

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Winter 2012 Edition 35

sense. Take the case in which Jones and Jones2 have exactly similar lives

throughout: which 85% of the 100% similar mental events do they share?

Nor does it make sense to suggest that Jones might have participated in

the whole of Jones2's psychic life, but in a rather ghostly only 85% there

manner. Clearly, the notion of overlap of numerically identical psychic

parts cannot be applied in the way that overlap of actual bodily part

constitution quite unproblematically can.

This might make one try the second answer. We can apply the ‘overlap’

answer to the Jones body, but the question of whether the minds or

subjects would have been the same, has no clear sense. It is difficult to

see why it does not. Suppose Jones found out that he had originally been

one of twins, in the sense that the zygote from which he developed had

divided, but that the other half had died soon afterwards. He can entertain

the thought that if it had been his half that had died, he would never have

existed as a conscious being, though someone would whose life, both

inner and outer, might have been very similar to his. He might feel rather

guiltily grateful that it was the other half that died. It would be strange to

think that Jones is wrong to think that there is a matter of fact about this.

And how is one to ‘manage’ the transition from the case where there is a

matter of fact to the case where there is not?

If the reasoning above is correct, one is left with only the first option. If

so, there has to be an absolute matter of fact from the subjective point of

view. But the physical examples we have considered show that when

something is essentially complex, this cannot be the case. When there is

constitution, degree and overlap of constitution are inevitably possible. So

the mind must be simple, and this is possible only if it is something like a

Cartesian substance.

4.5 The Aristotelian Argument in a Modern Form

Putting his anti-materialist argument outlined above, in section 1, in very

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general terms, Aristotle's worry was that a material organ could not have

the range and flexibility that are required for human thought. His worries

concerned the cramping effect that matter would have on the range of

objects that intellect could accommodate. Parallel modern concerns centre

on the restriction that matter would impose on the range of rational

processes that we could exhibit. Godel, for example, believed that his

famous theorem showed that there are demonstrably rational forms of

mathematical thought of which humans are capable which could not be

exhibited by a mechanical or formal system of a sort that a physical mind

would have to be. Penrose (1990) has argued that Turing's halting

problem has similar consequences. In general, the fear is that the

materialist monist has to treat the organ of thought as, what Dennett

(1987:61) calls, a syntactic engine: that is, as something that operates

without any fundamental reference to the propositional content of what it

thinks. It works as a machine that only shadows the pattern of meaning.

But it is hard to convince oneself that, as one, for example, reflectively

discusses philosophy and struggles to follow what is being said, that it is

not the semantic content that is driving one's responses. But if we are

truly semantic engines, it is difficult to see how we can avoid at least a

property dualism. These issues are, of course, connected with problems

raised by Brentano, concerning the irreducibility of intentionality. Despite

the interest of the arguments for dualism based on the irreducible

flexibility of intellect, most of the modern debate turns on arguments that

have a Cartesian origin.

5. Problems for Dualism

We have already discussed the problem of interaction. In this section we

shall consider two other facets of dualism that worry critics. First, there is

what one might term the queerness of the mental if conceived of as non-

physical. Second there is the difficulty of giving an account of the unity

of the mind. We shall consider this latter as it faces both the bundle

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theorist and the substance dualist.

5.1 The Queerness of the Mental

Mental states are characterised by two main properties, subjectivity,

otherwise known as privileged access, and intentionality. Physical objects

and their properties are sometimes observable and sometimes not, but any

physical object is equally accessible, in principle, to anyone. From the

right location, we could all see the tree in the quad, and, though none of

us can observe an electron directly, everyone is equally capable of

detecting it in the same ways using instruments. But the possessor of

mental states has a privileged access to them that no-one else can share.

That is why there is a sceptical ‘problem of other minds’, but no

corresponding ‘problem of my own mind’. This suggests to some

philosophers that minds are not ordinary occupants of physical space.

Physical objects are spatio-temporal, and bear spatio-temporal and causal

relations to each other. Mental states seem to have causal powers, but

they also possess the mysterious property of intentionality—being about

other things—including things like Zeus and the square root of minus one,

which do not exist. No mere physical thing could be said to be, in a literal

sense, ‘about’ something else. The nature of the mental is both queer and

elusive. In Ryle's deliberately abusive phrase, the mind, as the dualist

conceives of it, is a ‘ghost in a machine’. Ghosts are mysterious and

unintelligible: machines are composed of identifiable parts and work on

intelligible principles. But this contrast holds only if we stick to a

Newtonian and common-sense view of the material. Think instead of

energy and force-fields in a space-time that possesses none of the

properties that our senses seem to reveal: on this conception, we seem to

be able to attribute to matter nothing beyond an abstruse mathematical

structure. Whilst the material world, because of its mathematicalisation,

forms a tighter abstract system than mind, the sensible properties that

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figure as the objects of mental states constitute the only intelligible

content for any concrete picture of the world that we can devise. Perhaps

the world within the experiencing mind is, once one considers it properly,

no more—or even less—queer than the world outside it.

5.2 The Unity of the Mind

Whether one believes that the mind is a substance or just a bundle of

properties, the same challenge arises, which is to explain the nature of the

unity of the immaterial mind. For the Cartesian, that means explaining

how he understands the notion of immaterial substance. For the Humean,

the issue is to explain the nature of the relationship between the different

elements in the bundle that binds them into one thing. Neither tradition

has been notably successful in this latter task: indeed, Hume, in the

appendix to the Treatise, declared himself wholly mystified by the

problem, rejecting his own initial solution (though quite why is not clear

from the text).

5.2.1 Unity and Bundle Dualism

If the mind is only a bundle of properties, without a mental substance to

unite them, then an account is needed of what constitutes its unity. The

only route appears to be to postulate a primitive relation of co-

consciousness in which the various elements stand to each other.

There are two strategies which can be used to attack the bundle theory.

One is to claim that our intuitions favour belief in a subject and that the

arguments presented in favour of the bundle alternative are unsuccessful,

so the intuition stands. The other is to try to refute the theory itself. Foster

(1991, 212–9) takes the former path. This is not effective against

someone who thinks that metaphysical economy gives a prima facie

priority to bundle theories, on account of their avoiding mysterious

substances.

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Winter 2012 Edition 39

The core objection to bundle theories (see, for example, Armstrong

(1968), 21–3) is that, because it takes individual mental contents as its

elements, such contents should be able to exist alone, as could the

individual bricks from a house. Hume accepted this consequence, but

most philosophers regard it as absurd. There could not be a mind that

consisted of a lone pain or red after-image, especially not of one that had

detached itself from the mind to which it had previously belonged.

Therefore it makes more sense to think of mental contents as modes of a

subject.

Bundle theorists tend to take phenomenal contents as the primary

elements in their bundle. Thus the problem is how to relate, say, the

visual field to the auditory field, producing a ‘unity of apperception’, that

is, a total experience that seems to be presented to a single subject. Seeing

the problem in this way has obvious Humean roots. This atomistic

conception of the problem becomes less natural if one tries to

accommodate other kinds of mental activity and contents. How are acts of

conceptualising, attending to or willing with respect to, such perceptual

contents to be conceived? These kinds of mental acts seem to be less

naturally treated as atomic elements in a bundle, bound by a passive unity

of apperception. William James (1890, vol. 1, 336–41) attempts to answer

these problems. He claims to introspect in himself a ‘pulse of thought’ for

each present moment, which he calls ‘the Thought’ and which is the

‘vehicle of the judgement of identity’ and the ‘vehicle of choice as well as

of cognition’. These ‘pulses’ are united over time because each

‘appropriates’ the past Thoughts and ‘makes us say “as sure as I exist,

those past facts were part of myself”. James attributes to these Thoughts

acts of judging, attending, willing etc, and this may seem incoherent in

the absence of a genuine subject. But there is also a tendency to treat

many if not all aspects of agency as mere awareness of bodily actions or

tendencies, which moves one back towards a more normal Humean

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position. Whether James' position really improves on Hume's, or merely

mystifies it, is still a moot point. (But see Sprigge (1993), 84–97, for an

excellent, sympathetic discussion.)

5.2.2 Unity and Substance Dualism

The problem is to explain what kind of a thing an immaterial substance is,

such that its presence explains the unity of the mind. The answers given

can be divided into three kinds.

(a) The ‘ectoplasm’ account: The view that immaterial substance is a kind

of immaterial stuff. There are two problems with this approach. First, in

so far as this ‘ectoplasm’ has any characterisation as a ‘stuff’—that is, a

structure of its own over and above the explicitly mental properties that it

sustains—it leaves it as much a mystery why this kind of stuff should

support consciousness as it is why ordinary matter should. Second, and

connectedly, it is not clear in what sense such stuff is immaterial, except

in the sense that it cannot be integrated into the normal scientific account

of the physical world. Why is it not just an aberrant kind of physical

stuff?

(b) The ‘consciousness' account: The view that consciousness is the

substance. Account (a) allowed the immaterial substance to have a nature

over and above the kinds of state we would regard as mental. The

consciousness account does not. This is Descartes' view. The most

obvious objection to this theory is that it does not allow the subject to

exist when unconscious. This forces one to take one of four possible

theories. One could claim (i) that we are conscious when we do not seem

to be (which was Descartes' view): or (ii) that we exist intermittently,

though are still the same thing (which is Swinburne's theory, (1997),

179): or (iii) that each of us consists of a series of substances, changed at

any break in consciousness, which pushes one towards a constructivist

Howard Robinson

Winter 2012 Edition 41

account of identity through time and so towards the spirit of the bundle

theory: or (iv) even more speculatively, that the self stands in such a

relation to the normal time series that its own continued existence is not

brought into question by its failure to be present in time at those moments

when it is not conscious within that series (Robinson, forthcoming).

analysis. This is Foster's view, though I think Vendler (1984) and Madell

(1981) have similar positions. Foster argues that even the ‘consciousness’

account is an attempt to explain what the immaterial self is ‘made of’

which assimilates it too far towards a kind of physical substance. In other

words, Descartes has only half escaped from the ‘ectoplasmic’ model. (He

has half escaped because he does not attribute non-mental properties to

the self, but he is still captured by trying to explain what it is made of.)

Foster (1991) expresses it as follows:

…it seems to me that when I focus on myself introspectively, I am

not only aware of being in a certain mental condition; I am also

aware, with the same kind of immediacy, of being a certain sort of

thing…

It will now be asked: ‘Well, what is this nature, this sortal

attribute? Let's have it specified!’ But such a demand is

misconceived. Of course, I can give it a verbal label: for instance,

I can call it ‘subjectness’ or ‘selfhood’. But unless they are

interpreted ‘ostensively’, by reference to what is revealed by

introspective awareness, such labels will not convey anything over

and above the nominal essence of the term ‘basic subject’. In this

respect, however, there is no difference between this attribute,

which constitutes the subject's essential nature, and the specific

psychological attributes of his conscious life…

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Berkeley's concept of notion again helps here. One can interpret Berkeley

as implying that there is more to the self than introspection can capture, or

we can interpret him as saying that notions, though presenting stranger

entities than ideas, capture them just as totally. The latter is the ‘no

account is needed’ view.

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