Dualistic Interactionist Philosophies of Mind

Dualistic Interactionist Philosophies of Mind

Introduction

• The fundamental question is: What constitutes a human person?

  • Are we animals, souls, a combination, or something else?

  • If the concept of a 'soul' is invoked, its nature must be defined.

Five Philosophies of Mind

• Simple Dualistic Interactionism

• Compound Dualistic Interactionism

• Epiphenomenalism

• Physical Monism

• Hylomorphism

Simple and Compound Dualistic Interactionism

Key Definitions:

• Substance (according to SD): =_{df} an individual thing that can act or be acted upon.

• Substance dualism: (df) the view that human persons are composed of two distinct substances usually called the mind and the body.

• Simple substance dualism: (df) the view that human persons are simple substances and have only the property of being a substance as well as being immaterial.

• Compound Substance dualism: (df) the view that human persons are composed of an immaterial substance and a material substance and those substances work in conjunction.

• Interactionism: The doctrine that says that:

  • (a) a human person, e.g., Joe’s, mind can have DIRECT causal influence on Joe’s body, e.g., Joe’s mind directly causes Joe’s body to move.

  • (b) Joe’s mind can have DIRECT causal influence on itself, e.g., Joe’s mind can directly cause itself to do things, e.g., will to think about the nature of human minds.

  • (c) Joe’s body can have DIRECT causal influence on other bodies, e.g., Joe’s body can directly move bodies it is in immediate contact with.

  • (d) other bodies can have DIRECT causal influence on Joe’s body, e.g., bodies other than those of Joe’s body can directly cause things to happen to Joe’s body, e.g., put pressure on Joe’s body.

  • (e) Joe’s body can have DIRECT causal influence on Joe’s mind, e.g., cause Joe to feel physical pain.

  • (f) Joe’s mind can only have INDIRECT causal influence on other minds, e.g., by way of causing his body to do something, which has an effect on the bodies of others, which in turn causes an effect in the mind of someone other than Joe.

  • (g) Joe’s mind can only have INDIRECT causal influence on bodies other than his own, e.g., by way of causing his body to do something, where Joe’s body directly causes something to happen to a body other than Joe’s body.

• Dualistic Interactionism: (df) The combination of substance dualism along with interactionism.

• Simple dualistic interactionism: (df) The combination of simple substance dualism along with interactionism.

• Compound dualistic interactionism: (df) The combination of compound substance dualism with interactionism.

Examples of Substances

Compound Substance Dualism

*Compound substance dualism =_{df} (a) substance dualism is true, (b) a human person S necessarily has an immaterial substance as a part, and (c) a human person S normally, but not necessarily, has a material substance as a part.

Arguments in Defense of Dualistic Interactionism

1. Descartes’ Argument from Libertarian Free Will

1. The behavior of physical substances is determined.

2. If the behavior of human persons is not determined, then human persons are not identical to physical substances [from (1)].

3. If human persons have freewill, then the behavior of human persons is not determined [self-evident].

4. Therefore, if human persons have freewill, then human persons are not identical to physical substances [from (2) and (3), HS].

5. Human persons have free will.

6. Therefore, human persons are not identical to physical substances [from (4) and (5), MP].

7. Human persons are substances.

8. Therefore, human persons are immaterial substances or a compound of an immaterial substance and a material substance [from (6) and (7)].

9. Human persons (or human souls) can directly causally interact with their bodies, and vice versa [call this the interaction intuition].

10. Therefore, some sort of dualistic interactionism is true [from (8) and (9)].

• Event E’s being causally determined: Event E is causally determined =_{df} E had to happen because of events antecedent to E.

• An account of libertarian freewill: Joe’s act A at time t is free in the libertarian sense iff Joe performs A and Joe’s act A is caused by the workings of Joe’s intellect and will, and, at t, Joe could have done otherwise than perform A, i.e., Joe’s act A at time t is a real choice.

Why think we have libertarian freewill? (Four arguments for the price of one!)

1. If human persons don’t have libertarian freewill, then human persons never really make choices, i.e., they are not able to do otherwise [self-evident].

2. Sometimes human persons make choices [assumption].

3. If human persons never make choices, then it is never the case that a human person S’s moral character is (to some degree) up to S.

4. Sometimes it is the case that a human person S’s moral character is (to some degree) up to S [assumption].

5. If it is never the case that a person S’s moral character is (to some degree) up to S, then human persons are never morally responsible for their actions [assumption].

6. Sometimes human persons are morally responsible for their actions [assumption].

7. If human persons are never morally responsible for their actions, then human persons never deserve reward or punishment [assumption].

8. Sometimes human persons deserve reward or punishment [assumption].

9. Therefore, we do have libertarian freewill [from (1) and (2), by MT; from (1), (3), and (4), by HS and MT; from (1), (3), (5), and (6), by HS and MT; from (1), (3), (5), (7) and (8), by HS and MT].

2. The Simple Argument from Personal Identity

Preliminaries

• Absolute identity (df) x and y are absolutely identical if and only if x and y do not differ in any respect, e.g., the referent of ‘Superman at time t’ and the referent of ‘Klark Kent at time t’ are absolutely identical.

• Specific identity (df) x and y are specifically identical if and only if x and y do not differ in species, e.g., Dr. Brown’s organism and _ are specifically identical since they both belong to the species homo sapiens.

• Numerical identity = (df) x and y are numerically identical if and only if x and y are the same individual substance, e.g., we would typically think that Dr. Brown today and Dr. Brown last Friday are numerically identical (although Dr. Brown today and Dr. Brown last Friday are not absolutely identical).

• Personal identity = (df) x and y are personally identical if and only if (a) x is a person, (b) y is a person, and (c) x and y are numerically identical, i.e., the same individual substance.

Argument from Personal Identity Through Time and Change

1. A compound material object x and a compound material object y are numerically identical only if they are composed of numerically identical material parts.

2. Human organisms constantly undergo changes with respect to their parts and total replacement of their parts every seven years or so [assumption].

3. Therefore, if (a) human persons are numerically identical to human organisms, then (b) no human person lasts long enough to be held morally accountable for their actions, accomplish projects, maintain friendships and marriages, etc. [from (1) and (2)].

4. But human persons sometimes do last long enough to be held morally accountable for their actions, accomplish projects, maintain friendships and marriages, etc. [assumption].

5. Therefore, it is not the case that human persons are numerically identical to human organisms [from (3) and (4), by MT].

6. Substance dualism is true or human persons are wholly material objects, i.e., human persons are numerically identical to human organisms [assumption].

7. Substance dualism is true [from (5) and (6), by DS].

8. The human mind can directly causally interact with the human body and vice versa [the interaction intuition].

9. Therefore, DI [from (7) and (8), Addition].

Advanced Consideration for Premise (1)

1. Whatever else we want to say about a compound material object, it is true that there is an aggregate of physical simples existing wherever that compound material object exists [assumption].

2. If it is not the case that a compound physical object is numerically identical to an aggregate of physical simples, then (i) wherever the compound material object exists, there are two material objects existing in the same place at the same time, namely, the compound material object and the aggregate of physical simples that constitutes it [from (a)].

3. (i) is false [assumption].

4. Therefore, it is not the case that it is not the case that a compound physical object is numerically identical to an aggregate of physical simples [from (b) and (c), MT].

5. Therefore, a compound physical object is numerically identical to an aggregate of physical simples [from (d), DN].

6. If an aggregate A and an aggregate A1 have numerically different parts, then A and A1 are not numerically identical aggregates [assumption].

7. Therefore, if a compound physical object x and a compound physical object y are composed of numerically different parts, then x and y are not numerically identical physical objects [from (e) and (f)].

8. Therefore, if human persons are numerically identical to human organisms, then a human person S is numerically—and so personally—identical to a person S1 only if S and S1 are composed of the same matter [from (g)].

Schema for a Different Version of the Argument

1. If weak physicalism, then personal identity through time and change for beings such as ourselves is impossible, or (a) personal identity through time and change is a function of sameness of matter, or sameness of body, or sameness of brain, or spatiotemporal continuity, or psychological continuity.

2. Personal identity through time and change is possible.

3. There are good counter-examples to (a).

4. Therefore, weak physicalism is false.

Problems with physicalist criteria of numerical identity through time change

• Sameness of matter

  • Not necessary: Dr. Brown at Muse concert

  • Not sufficient: God collects particles example

• Sameness of body

  • Not necessary: transplanting your brain to a different body example

  • Not sufficient: ditto

• Sameness of brain

  • Not necessary: transfer half of information to left half of brain; take away right half of your brain; add a new half, etc.

  • Not sufficient: transfer halves of a brain into two empty skulls; it is possible you have not survived; destroy one of the halves. It is possible you have not survived but your brain has (it is just a little smaller)

• Spatio-temporal continuity

  • Not necessary: transporter example

  • Not sufficient: cut a person into two; keep one half alive, and the other half too.

• Psychological continuity

  • Not necessary: amnesia; conversion

  • Not sufficient: transfer of memories and psychology cases

Five Objections to DI

1. The Causal Interaction Argument

2. The Essence Argument

3. The Argument from Common Speech

4. The Brain Trauma Argument

5. The Unity of the Cognizer Argument

1. The Causal Interaction Argument

1. According to DI, a non-physical substance directly causally interacts with a physical substance, and vice versa.

2. If DI is plausible, then we can explain how a non- physical substance can directly causally interact with a physical substance, and vice versa [assumption].

3. But we can’t offer an explanation of how a non- physical substance can directly causally interact with a physical substance, and vice versa [assumption].

4. Therefore, DI is not plausible [from (1)-(3), by MT].

2. The Essence Argument

1. If we can’t understand the meaning of the expression, ‘non-physical substance,’ then substance dualism (SD) is not a plausible position in the philosophy of mind.

2. We can’t understand the meaning of the expression, ‘non-physical substance.’

3. Therefore, SD is not a plausible position in the philosophy of mind.

Disambiguating the Essence Argument:

First way:

1. (*): If we can’t understand the meaning of the expression, ‘non-physical substance’, i.e., we can’t give an empirically precise description of a non- physical substance, then SD is not a plausible position in the philosophy of mind.

2. (*): We can’t understand the meaning of the expression, ‘non-physical substance’, i.e., we can’t give an empirically precise description of non- physical substances.

3. Therefore, SD is not a plausible position in the philosophy of mind.

Second way:

1. (**): If we can’t understand the meaning of the expression, ‘non-physical substance’, i.e., we can’t give a philosophically precise description of non- physical substances, then SD is not a plausible position in the phil. of mind.

2. (**): We can’t understand the meaning of the expression, ‘non-physical substance’, i.e., we can’t give a philosophically precise description of non- physical substance.

3. Therefore, SD is not a plausible position in the philosophy of mind.

Why believe premise (1*) of the Essence Argument?

1. A proposition, concept, belief, theory is describable in an empirically precise way only if a proposition, concept, belief, or theory can be reduced to a mathematical equation and/or a statement that is verifiable/falsifiable by way of a scientific experiment.

2. Only propositions, concepts, beliefs, and theories that are describable in an empirically precise way, e.g., by way of biology, chemistry, or empirical physics, are meaningful.

3. Therefore, if we can’t give an empirically precise description of non-physical substance, then DI is not a plausible position i [from (a) and (b)].

Descartes on the meaning of non-physical substance

• a substance that experiences, remembers, recognizes, thinks, questions, believes, knows, understands, judges, reasons, desires, hopes, and chooses.

Objection to the location of a non-physical substance

• Where, meaning #1: the place where an object takes up space.

• Where, meaning #2: the place at which an object exercises its causality.

• Non-physical substances are not anywhere in the sense of where, meaning #1, for they are immaterial and so non-spatial substances.

• But they can be and are somewhere in the sense of meaning #2, namely, where our bodies are, at least in this life.

3. The Argument from Common Speech

1. All other things being equal, the way we commonly speak about reality is an accurate guide to reality.

2. The way we commonly speak about ourselves is not consistent with substance dualism, or perhaps, more specifically dualistic interactionism.

3. Therefore, all other things being equal, we should reject (dualistic) substance dualism for some other hypothesis about the nature of human persons that is compatible with the way in which we speak about human persons [from (1) and (2)].

4. If ~SD, then ~DI [self-evident].

5. Therefore, all other things being equal, we should reject (dualistic) DI for some other hypothesis about the nature of human persons that is compatible with the way in which we speak about human persons [from (3) and (4)].

4. The Brain Trauma Argument

1. If (a) DI, then (b) the human mind is to the human brain as Alfred (along with his remote controller) is to his remote-controlled toy airplane [assumption].

2. If Alfred’s toy airplane breaks, Alfred DOES NOT thereby fall into an unconscious state or a state of reduced consciousness (neither does the remote controller break just in virtue of damage done to the toy airplane). Rather, Alfred can be fully conscious, e.g., thinking, willing, and desiring (in the manner in which we do when we are awake), all the while his toy airplane is broken [assumption].

3. Therefore, if (b) the human mind is to the human brain as Alfred (along with his remote controller) is to his toy airplane, then (c) when a human brain is in a state of serious trauma, the corresponding human mind DOES NOT thereby fall into an unconscious state or a state of reduced consciousness. Rather, the human mind correlated with a human brain in serious trauma is fully conscious, e.g., thinking, desiring, willing (in the manner that we do when we are awake), all the while the brain is in a state of serious trauma [from (2)].

4. Therefore, if (a) DI, then (c) when a human brain is in a state of serious trauma, the corresponding human mind DOES NOT thereby fall into an unconscious state or a state of reduced consciousness. Rather, the human mind correlated with a human brain in serious trauma is fully conscious, e.g., thinking, desiring, willing (in the manner that we do when we are awake), all the while the brain is in a state of serious trauma [from (1) and (3), by HS ].

5. But when a human brain is in a state of serious trauma, the corresponding human mind DOES thereby fall into an unconscious state or a state of reduced consciousness [not (c); assumption from experience].

6. Therefore, not (a) DI [from (4) and (5), by MT].

Brain Trauma Analogy

• Mind or soul :: Alfred (and his remote controller)

• Brain :: Alfred’s remote control airplane

Better Analogy for DI

• Mind or soul :: A wheel

• Brain :: The axle to which the wheel is (sometimes) attached

• Mind or soul :: A person sailing at sea

• Brain or body :: A person’s sailboat

5. The Unity of the Cognizer Argument

1. If DI, then either SDI or CDI [assumption].

2. IF SDI, then (a) the non-physical substance which is identical to the self is what senses, i.e., sees, hears, smells, etc. or (b) the five senses are powers that belong to the body and we don’t really sense things, our bodies do [self-evident].

3. IF CDI, then (c) we are not one substance but one compound, a soul which thinks but does not smell things and a body that smells things but does not think [self-evident].

4. Not (a); since seeing, smelling, and hearing, etc., involve the use of physical organs, it does not make sense to say that a non-physical substance sees, hears, smells, etc. [assumption].

5. But we are one substance, i.e., one subject, that both thinks and senses [assumption from experience of ourselves as unified cognizers].

6. Therefore, not (b) and not (c) [from (5)].

7. Therefore, not SDI [from (2), (4), and (6), MT].

8. Therefore, not CDI [from (3) and (6), MT].

9. Therefore, not DI [from (1), (7) and (8), MT].