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1 PSY 3360 / CGS 3325 Historical Perspectives on Psychology Minds and Machines since 1600 Dr. Peter Assmann Spring 2020 René Descartes (1596-1650) French mathematician, philosopher, and physiologist Descartes’ Method 1. Never accept anything as true unless it can be clearly shown as such (the skeptical approach). 2. Separate each complex problem into as many parts as you can, and solve each one separately. Descartes’ Method 3. Rank the problems that you face in order of difficulty, and tackle them by starting with the simplest and easiest, and gradually moving to the more difficult ones. 4. Make an exhaustive and systematic review of your conclusions and the process that led you to them, so that nothing will be left out. Cogito, ergo sum “I think, therefore I am” Skepticism and the “Cartesian doubt” – systematically call into question and challenge all assumptions and ideas, so that what is left is unquestionable and solid. Cogito argument – something must exist (a conscious agent) in order to do the thinking and doubting. Rationalism Some ideas are not invented or discovered, but inherent or innate. Their truth is self- evident, not derived from experience. Rationalism is the view that true knowledge is ultimately derived from a process of rational thought.

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Page 1: René Descartes (1596-1650) PSY 3360 / CGS 3325 Historical ...assmann/PSY3360/lec4.pdfProblem of other minds If the only thing we can be absolutely certain of is the existence of our

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PSY 3360 / CGS 3325Historical Perspectives

on PsychologyMinds and Machines since 1600

Dr. Peter Assmann

Spring 2020

René Descartes (1596-1650)

French mathematician, philosopher, and physiologist

Descartes’ Method

1. Never accept anything as true unless it can be clearly shown as such (the skeptical approach).

2. Separate each complex problem into as many parts as you can, and solve each one separately.

Descartes’ Method

3. Rank the problems that you face in order of difficulty, and tackle them by starting with the simplest and easiest, and gradually moving to the more difficult ones.

4. Make an exhaustive and systematic review of your conclusions and the process that led you to them, so that nothing will be left out.

Cogito, ergo sum“I think, therefore I am”

• Skepticism and the “Cartesian doubt” – systematically call into question and challenge all

assumptions and ideas, so that what is left is unquestionable and solid.

• Cogito argument– something must exist (a conscious agent) in order

to do the thinking and doubting.

Rationalism

• Some ideas are not invented or discovered,

but inherent or innate. Their truth is self-

evident, not derived from experience.

• Rationalism is the view that true knowledge

is ultimately derived from a process of

rational thought.

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“Clockwork universe”

• Descartes’ mechanistic view of the physical world: physical principles explain the workings of the physical world, as well as physiological processes of digestion, growth, respiration, and sensation in humans & animals.

• But the human mind lies outside the realm of the physical; not amenable to scientific study.

Animal spirits• Concept originated in ancient Greece (300 BCE)

• Invisible, weightless substance that flowed through hollow nerves

• Concept introduced by Galen (129-216 AD)– Natural spirits derived from nutrients via the liver

– Transformed into animal spirits when mixed with inhaled air

– Animal spirits flowed from the brain to other parts of the body

Vesalius (1514–1564)

• Anatomy: De humani corporis fabrica

• Disagreed with Galen on the structure of the brain and the role of animal spirits; did not believe that nerves were hollow

Hydromechanical theory of nerve transmission

• William Harvey - circulatory system

• The primary sense receptors of animals and humans are like pressure plates that start the flow of animal spiritsthrough a series of pipes.

Theory of reflex behavior Theory of depth perception

• Doctrine of innate ideas

• Binocular vision

• Role of geometry

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Pineal gland

The pineal gland is an endocrine organ, which produces the hormone melatonin.

The problem for dualism

• If mind and body are fundamentally different entities, how do they interact?

• How do external objects and events leave their impressions on our awareness?

• How are thoughts, desires, and intentions translated into actions?

Interactionist dualism

• Rational decisions can lead to physical actions

• Events in the physical world are perceived by the mind

• Mind and body interact through a single pathway

• Special role of the pineal gland in the human nervous system

The “Ghost in the Machine”

• The mental and physical worlds are distinct.

• The body is constrained by physical laws of space and time; the mind is an abstract and non-material entity.

• Plausible mechanism for interaction?

Problem of other minds

If the only thing we can be absolutely certain of is the existence of our own minds doing the thinking and doubting, how can we ever possibly know whether other people exist, have minds and thoughts like we do?

Self-awareness is a private state

Les passions

Theory of emotion

Mind‐body interaction

Role of the pineal gland

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Descartes moves to Sweden Descartes’ Legacy

• What problem for the study of mind and behavior was raised by Descartes’ Cogitoargument? 

• Why should we care?

“By localizing the soul’s contact with body in the pineal gland, Descartes had raised the question of the relationship of mind to the brain and nervous system. Yet at the same time, by drawing a radical ontological distinction between body as extended and mind as pure thought, Descartes, in search of certitude, had paradoxically created intellectual chaos.” (Robert Wozniak)

Descartes

• Nativism: Some ideas are not invented or discovered, but inherent or innate. Their truth is self-evident, not derived from experience.

• Rationalism: True knowledge is ultimately derived from a process of rational thought.

• Dualism: Mind and body are distinct and different; simple physical principles explain the workings of the physical world, but the human mind lies outside the physical realm.

Discussion Questions

1. Although most of Descartes’ specific formulations about the ways the human body and brain work have been discarded, why are his ideas relevant for understanding the history of scientific psychology?

2. Descartes believed that there are some concepts or ideas that can never be directly apprehended in experience, such as perfection or unity. Do you agree? How do we come to an understanding or knowledge of these concepts that we all share?

3. What are some of the implications of Descartes’ mind‐body problem for neuroscientists in the 21st century?

Paralysed patients control robotic arm with thoughts

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Two Rationalist Alternatives:

Spinoza Leibniz

Monist Dualist

Some key terms

• Dualism– Interactionist dualism (Descartes)

– Psychophysical parallelism (Leibniz)

• Monism– Mental monism (Berkeley)

– Physical monism (Hobbes, Gassendi)

– Dual-aspect (neutral) monism (Spinoza)

The Mind-Body Problem

• Descartes – interactionist dualism

• Spinoza – neutral (double-aspect) monism

• Leibniz – psychophysical parallelism

Events and dates1478 Spanish Inquisition

1497 Portuguese Jews (including Spinoza’sancestors) forced to convert or be expelled.

1616 Death of Shakespeare

1618 Beginning of the Thirty Years War

1628 William Harvey discovers the mechanisms of the human circulatory system

1629 Descartes moves to Holland

1632 Spinoza was born

Events and dates1632 Anton van Leeuwenhoeck (inventor of the

microscope) born in Amsterdam1632 Galileo was denounced by the Inquisition.1637 Descartes publishes Discourse on Method1642 Isaac Newton was born1646 Gottfried Wilhelm von Leibniz was born1648 End of the Thirty Years War1651 Spinoza first became aware of Descartes’

work, one year after his death1655 Spinoza accused of heresy; is expelled from

the Amsterdam Synagogue.

Baruch Spinoza (1632-1677)

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Baruch Spinoza (1632-1677)• Jewish philosopher and mathematician• Expelled from the Amsterdam synagogue for

his unorthodox views in 1656• Declined the Chair of Philosophy at

Heidelberg University in 1673 to maintain his independence

• Lived modestly; earned his living as a lens grinder

• Died of consumption, aggravated by the dust from lens grinding

B. Spinoza Ethics

Spinoza’s rejection of dualism

• Dual aspect (neutral) monism: equivalence of mind and matter

• Pantheism: inseparability of nature and God• Deductive method: start with a small

number of principles or axioms regarded as “self-evident” and use them to arrive at other true statements

• Moral and ethical principles

Spinoza’s moral / ethical philosophy

• Determinism: if humans are part of nature, and subject to its laws, then all aspects of human experience are determined.

• Freedom: consists in knowing that all events have causes, and living one’s life in pursuit of the knowledge of the causes of things.

• Hedonism: “good” and “evil” are nothing more than the experiences of pleasure and pain.

Psychic determinism

• Spinoza’s monist solution to the mind-body problem implies that mental experiences are subject to natural laws and can be studied in the same way as the physical world.

• Foreshadows the possibility of a scientific psychology.

Gottfried Willhelm von Leibniz (1646-1716)

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Psychophysical parallelism• Dualist solution to the mind-body problem• There is a close correlation between mental

events and physical events• But physical events do not interact with or

influence mental events (or vice versa). They are fundamentally different.

• Metaphor of two clocks in perfect synchrony• Pre-established harmony

Monadology

• Anton van Leeuwenhoek (1632-1723)

• The universe is populated by living things

• monads - indivisible units that make up the universe. – rational monads

– sentient monads

– simple monads

Leibniz

• Nativism: the mind is like a block of veined marble

• Apperception

• Minute perceptions

The Stepped Reckoner

...it is beneath the dignity of excellent men to waste their time in calculation when any peasant could do the work just as accurately with the aid of a machine. Gottfried Leibniz[1]

Leibniz1671

Pierre Gassendi (1592-1655)

• French empiricist philosopher / mathematician

• Material (physical) monism

• Observation-based science

• Induction and deduction