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1 Thomas Aquinas Thomas Aquinas Lived 1225-1274AD. The Catholic church came to prominence around 500AD—1500AD. Christianity was the dominant religion. Aquinas was one of the greatest interpreters of Aristotle’s work. He showed that Aristotle’s views could be reconciled with Christianity. Thomas Aquinas In Aristotle we see a division amongst the animals by way of the kind of soul they possess—nutritive, sensitive, rational. This is a hierarchical ordering. The Scala Natura—The Great Chain of Being. The Scala Natura—The Great Chain of Being Pure Actuality (Prime Mover) – Humans (Rational) – Animals (Sensitive) – Plants (Nutritive) – Non-living natural objects (e.g. rocks, bone..) – The elements (earth, air, fire, water) Pure substance/Pure Potentiality The Scala Natura—The Great Chain of Being For Aquinas, things were ordered in the world according to their perfection and reflecting God’s plan. Humans are close to the top of the chain of being, with God at the very top. Everything has a purpose (teleology)—God is the Final Cause of all in the world. The Great Chain of Being reflects God’s plan. Thus, the Aristotelian world-view is consistent with Christianity.

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Thomas Aquinas Thomas Aquinas

Lived 1225-1274AD. The Catholic church came to prominence

around 500AD1500AD. Christianity was the dominant religion. Aquinas was one of the greatest

interpreters of Aristotles work. He showed that Aristotles views could be

reconciled with Christianity.

Thomas Aquinas

In Aristotle we see a division amongst the animals by way of the kind of soul they possessnutritive, sensitive, rational.

This is a hierarchical ordering. The Scala NaturaThe Great Chain of

Being.

The Scala NaturaThe Great Chain of Being

Pure Actuality (Prime Mover) Humans (Rational) Animals (Sensitive) Plants (Nutritive) Non-living natural objects (e.g. rocks, bone..) The elements (earth, air, fire, water)

Pure substance/Pure Potentiality

The Scala NaturaThe Great Chain of Being

For Aquinas, things were ordered in the world according to their perfection and reflecting Gods plan.

Humans are close to the top of the chain of being, with God at the very top.

Everything has a purpose (teleology)God is the Final Cause of all in the world.

The Great Chain of Being reflects Gods plan. Thus, the Aristotelian world-view is consistent

with Christianity.

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The Scientific

Revolution

Nicolas Copernicus (1473-1543)

Nicolas Copernicus

Up until Copernicus publication of On the Revolutions of the Heavenly Bodies, the Ptolemaic (90-168AD) model of the universe was dominant theory.

Ptolemys model was a detailed mathematical account of the orbits of the planets that was geocentric (earth at the center).

Aristotle presented a geocentric cosmology earlier than Ptolemy.

Nicolas Copernicus

Copernicus revolutionized the way we viewed the planetary system by proposing that the sun was the center of the (known) universeheliocentric model of the universe.

This upset a great deal of traditional thinking.

Cosmology was tied to the notion of the Great Chain of Being.

Nicolas Copernicus

The Earth was the focus of Gods creation an as such was held to be the center universeGods plan.

As such his view was rejected by the Church. But it inaugurated an enormous shift in our

thinking about the world.

Francis Bacon (1561-1626)

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Francis Bacon Bacon ushered in a new way of thinking about how we

ought to go about understanding the world. It was the first articulation of the scientific methodin his

Novum Organona play on Aristotles Organon. Bacon was deeply critical of the ancients and challenged

the fundamental form of reasoning they used in the acquisition of knowledgethe deductive method.

He argued that there had been little progress to our understanding of the world and that a reform was required.

Francis Bacon In the place of deduction, he argued for an

inductive method of inquiry. Scientific reasoning is still held to be a form of

inductive reasoning. The goal was, through experience, to collect

facts in an unbiased way. Then on the basis of an analysis of these facts

we proceed to make modest generalizations about the nature of the worldinductive generalizations!

Francis Bacon

In outline, this is an articulation of the basic tenets of the scientific methodobservation, experimentation and generalization.

Challenging Aristotelian Science

Aristotles explanation of change and motion were informed by his cosmology.

As a result of Copernicus revolutionary changes to the model of the universe, central portions of Aristotles scientific system fell apart.

During this period of scientific innovation, Aristotles schema of matter and form also came under challenge.

Challenging Aristotelian Science

Critics argued that the claims became empty when applied to complex problems.

E.g. Aristotelians might say that sleeping powder achieves its result because it possesses sleep qualitiesthat which is potentially asleep becomes actually asleep in the presence of these qualities.

But this doesnt really help explain how the powder works.

Challenging Aristotelian Science Similar arguments can be presented against the

definition of the soul. Recall, the soul is the form of living things. But the form is also that which makes something

the kind of thing it is. Put these together and what Aristotle seems to

be saying is that soul is that which brings life to living things.

All truebut not very helpful. We want to know how the soul does this.

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Challenging Aristotelian Science

Apart from these internal problems to the Aristotelian system, it also faced new challenges presented by a new approach to science.

Most significantly, the new science rejected Aristotles explanations of cause and effect.

Change for Aristotle was explained in terms of things taking on forms and qualities.

Challenging Aristotelian Science Things move towards the full realization of

respective forms and qualities. E.g. the acorn becomes an oak because it has

the form built into it (its purpose/final cause is to become an oak)

Similarly, the earth is heavy because its proper place is the centre of the cosmos, so it will naturally move there.

Similarly, fire moves upwards towards its natural place in the outer regions.

Challenging Aristotelian ScienceMechanical Explanations Thinking of causation in these purposeful ways

is to think in terms of teleological explanations(ends, goals, purpose).

Compare this with modern ideas of motion. Law of inertia: in the absence of external force

an object will maintain a constant state of rest or uniform motion.

Matter is inertit has no natural direction of motion, or internal drive.

Challenging Aristotelian Science

In modern physics, motion is explained by external forces acting on objectswhich will maintain there current state in the absence of such forces.

These are mechanical explanations. A distinctive feature of the scientific

revolution occurring in the 1600s was the rejection of teleological explanation for mechanical explanation.

Challenging Aristotelian Science Part of the reason for this was the emptiness of

Aristotelian explanations. Theres no point in explaining change in terms of

goals etc., if the goal is just a re-description of the changewe already know that it changes, we want to know why.

E.g. to explain falling objects by saying that they naturally fall, isnt much help.

The forces proposed by mechanical explanations seemed better suited.

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Challenging Aristotelian ScienceMathematical Laws The new science also placed a great deal of

emphasis on mathematics as a tool for describing natural laws.

Aristotles system was qualitative in natureexplaining change as changes in qualitiesno mathematics.

A distinctive feature of the new science was the formulation of mathematical laws and the replacement of qualitative descriptions with quantitative ones (time, weight, distance).

E.g. v = d/t

Challenging Aristotelian Science Platonic revivalthe relationship between

mathematics and nature. As Aristotelian science became more

problematic, scholars in the middle ages returned to this Platonic notion.

E.g. Copernicus on his heliocentric model we find then in this arrangement an admirable harmony of the world, and a dependable, harmonious interconnection of the motion and size of the paths, such as otherwise cannot be discovered.

Galileo Galilei (1564 1642) Galileo Galilei

Galileo challenged the dominant Aristotelian theory of motion with his detailed studies of the times and motions of falling bodies.

Famous canon-ball/musket-ball experiment at the Tower of Pisa.

Also performed various pendulum and rolling ball experiments to show that Aristotelian theory of motion was inconsistent with the observable facts.

Galileo Galilei

Galileo had adopted the new science and its mechanical and mathematical explanations to explain motion.

As a result of his work, he faced increasing criticism by the Aristotelians, who were, not surprisingly on the side of the Church.

In 1663 he was imprisoned by the Inquisition for teaching Copernicus theory.

Galileo Galilei

The Aristotelians said that as he became a better mathematician he became a worse physicist, because he moved away from the world as it appears in simple observations, and focused instead on abstract and ideal mathematical descriptions of times and motions.

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Challenging Aristotelian Science (Again)

This shift in thinking also did damage to Aristotelian confidence in the reliability of perception.

Mathematical laws are idealizations of what we actually observe.

The acceptance of mathematical laws did not follow from their observability, but from the fact that they produced better predictions.

Challenging Aristotelian Science (Again)

This led the new scientists to think that the real qualities of objects are not necessarily the ones we perceive.

Thus, appearances (observation) may not be the ultimate guide to understanding the worldeven though it is the appearances we want explained.

And this ushered in new challenges to Aristotles account of the relation between the perceiving mind and the physical worldthat the real qualities of objects are not like the sensations we experience.

Galileo AgainAn Argument Against Aristotelian Perception Aristotle thought the qualities we perceive are

features of the objects of perception. Galileo argues that this is a misattribution of

things we know with our mind to the objects themselves.

Imagine being tickled lightly by a hand or a feather.

Everyone agrees the tickling belongs to us and not to the hand. Right?

Galileo Again

If we run our hand over a statue, no one thinks the statue feels a tickle.

Thus, the tickling is not a property of the hand (or feather).

It exists solely in the mind of the person being tickled.

The same goes for the other senses. Objects produce the sensation in us, but the do

not possess sensation.

Galileo Again

Galileo explained it instead as a result of the motion of particles of matter.

For example, he suggests that sensations of sound are the result of moving air particles causing a vibration on the eardrum.

Differences in vibration differences in the sensation of sound in the mind.

Galileo Again

For this and other reasons, Galileo thought that the only qualities that really exist in material objects are the sizes, shapes, and motions of the particles that cause sensations.

Tastes, odours, sounds, are merely sensations in our minds.

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Rene Descartes Rene Descartes

Lived (1596-1650). Francis Bacon (1561-1626). Galileo Galilei (1564 1642). Descartes was also an influential figure in

the new science. He was part scientist, part mathematician,

part philosopher.

Rene DescartesThe Meditations Descartes was obsessed with the idea that

scientific progress required that we have a means of examining all beliefsto separate those notions that are reliable from those that are not.

In short, his goal was to find a secure foundation for all of our knowledge.

This is Descartes Foundationalism. Like Galileo, he challenged the idea that

appearances should be the primary source of information about the world.

Rene Descartes This was to be achieved by the systematic rejection of

any assumptions that could possibly be called into doubt. And on the basis of the foundation and reason alone

(logic) we would secure (deduce) all knowledge. Descartes was Rationalist. How to doubt? Methodological Skepticism. There are two main arguments used to call all that we

can into doubt.

(1) The Dreaming Argument.(2) The Deceiver Argument.

Rene DescartesThe Cogito Given what has been set out in the previous

arguments Descartes/the reader now has grounds to doubt all his/her knowledge.

So where is this foundation that Descartes intended to find?

All he needs (like Archimedes) is one point that is certain and unshakeable to found his knowledge upon.

But, we have already doubted everythingwhat could possibly remain?

Rene Descartes

The one thing that seems difficult to doubt is that, there is some doubting going on.

Cogito ergo sum: I am thinking, therefore I exist.

This is the foundational piece of knowledge Descartes was looking for.

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From the Mind Onward

What is a thinking thing? It doubts, understands, affirms, denies, is

willing, imagines, perceivesbut do all of these attributes really belong to us?

They are all merely kinds of thinking. So, these ruminations support the idea

that the essence of the mind is thinkingit is a thinking substance.

From the Mind Onward

What can we know about the external world? Consider a piece of beeswax. Examine its sensible qualities. Tastes like honey; Smells like flowers; has

distinct colour, shape, size Now place it near a fire.

From the Mind Onward

Once again, lets examine its sensible qualities.

The taste is gone; the smell is gone; the colour and shape have changed, its larger in size

So what is essential to the wax? It cant be these sensible qualities since

they have all disappeared.

From the Mind Onward

But we still see that the wax continues to exist without them.

These are merely accidental features of the wax.

What we can say, at the very least, is that the wax takes up spacethat it is extended in general (it has extension).

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From the Mind Onward

How do we know this? The senses never give us a notion of

general extension because all objects come with a particular shape, size etc.

Extension is grasped by the understanding not through our senses.

So the essential feature of bodies is that they are extendedand this we know via the understanding.

From the Mind Onward

But Descartes realizes that he still cant be certain of these claims.

Thus, he ushers in (non-deceiving) God as a means of justifying these ideas.

This is the antidote to the deceiver argument.

I will leave aside the argument for the existence of God.

From the Mind Onward Once we accept that a non-deceiving God exists

(since deception would be contrary to his nature), then we can prove the certainty of our knowledge.

Thus, those ideas that are clear (i.e. vivid) and distinct must also be true, for, if they were not, God would be a deceiver.

In this way, the existence of God validates many of the ideas that we have.

Thus, clear and distinct ideas cannot be doubted, and they become our source of knowledge.

From the Mind Onward

Some of these clear and distinct ideas are built into use.g. mathematical ideas.

These are innate ideas: a perennial issue in psychology.

Descartes Dualism

So now we have two kinds of substances: thinking substances and extended substances.

The essence of the mind is that it is a thinking substance and the essence of material bodies is that they are extended in space.

On the basis of this Descartes claims that the mind is distinct from the bodymind/body dualism.

Descartes Dualism1. The fact that I clearly and distinctly

understand one thing apart from another is enough to make me certain that the two things are distinct.otherwise God is a deceiver.

2. I have a clear and distinct idea of myself as existing without a bodythe essence of mind is thoughtthe essence of body is extension.

3. Therefore, I am not my body (or God is a deceiver).Mind and body are distinct! Platonism again.

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Descartes Dualism

Descartes thought that the pineal gland was where the soul was located.

The reason for this was that all of the other parts of the brain are double.

The pineal gland represented was a single structure that couldhouse the soula unitary object.

Descartes Dualism Gilbert Ryle (1949) referred Descartes view as the

ghost in the machine. As a result of these commitments we can also describe

Descartes as an interactionistsince the immaterial mind must be supposed to interact with a material body.

This led to the Mind/Body problem that has been with us since (Behaviourism/Cognitive Science).

Descartes also assumed that we know things best through the understanding (mind), and thus the key to knowledge was introspection.

This became the foundation for later introspective psychologists (William James).

Descartes and the Body

Descartes also believed the mind to operate according to its own rules, given by God, while the body is subject to mechanical laws.

Descartes conceived of the body as a kind of mechanical device (machine)this was informed by some of the latest technological and scientific developments of the day.

Descartes and the Body The fire (A) displaces

the skin, which pulls a tiny thread (B), which opens a pore in the ventricle (F) allowing the "animal spirit" to flow through a hollow tube, which inflates the muscle of the leg, causing the foot to withdraw.

Descartes and the Body

The development of various tinker toys that mimicked animal actions were inspiring (e.g. Vaucansons duck).

This led to thinking of organisms as machines and gave rise to the possibility of building machines indistinguishable from animals.

This gave rise to the possibility of artificial life, robotics, and artificial intelligence.

Vaucansons Duck

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Descartes and the Body Though Descartes was skeptical that such

innovations would lead to mimicking human behaviour (Turing Test), he did think it was possible in the case of animals.

Though he though humans and animals were different, he saw no difference between animals and machinesthe were automatons.

This mechanical approach to the body would, in later history, be adopted as an approach to the mind.

More on Descartes Descartes had detailed theories about the

nature of perception. He developed the first comprehensive account

of the role of emotion in mental life (The Passions of the Soul).

He worked to develop a theory of mind/body interactionwhich he later integrated with his account of the passions.

Developed a robust methodology for inquiry. He had an elaborate cosmology.

Isaac Newton (1642-1727) Isaac Newton

Has been described as the greatest scientific genius the English-speaking peoples have produced.

He studied everything from alchemy to history. His most famous work is his Principiain which

he lays the foundation for classical physics. Interestingly, he spends a great deal of time

attacking the cosmology of Descartes, which was the going theory.

Isaac Newton One of Newtons greatest discoveries were his

basic laws of motion. E.g. The law of inertia (Law 1). These were expressed in mathematical terms

(recall Pythyagoras). The fact that all motion (from the planets to small

objects) can be captured by these basic laws was extremely profoundphysics unified science.

It suggested that the world was governed by these basic immutable (mathematical) laws.

Isaac Newton Science is an attempt to provide general

explanations of this sort. Psychology as a science strives to discover the

laws of human behaviour, thought, perception, etc.psychological laws.

Further, many psychologists have attempted to emulate the physical sciences by treating psychological events as physical events that follow the same laws that regulate other physical systems.

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Isaac Newton In this way, psychology as a subject matter is treated

essentially the same as physicsboth study the motion of physical systems (motion of objects vs. motion of organismsbehaviour).

Just as force is required to move physical objects (given the law of inertia), it is also required to move organisms.

And not just any force is sufficient (follows from second law of motion), it must be a strong enough force to initiate motion (e.g. pushing a dump-truck).

Force must exceed a threshold (neuronal excitation; awareness; hearing).

Isaac Newton Newton also did work in opticswhich was an attempt to

give a physical understanding of light and colour phenomena.

His prism experiment showed that light actually could be split into different kinds of lightthat white light is a composite of other colours.

He did not think that light had these properties, but it had the power (disposition) to create the subjective experience we have of colours.

Stimulus vs. subjective experience. A physical description will not exhaust our subjective

experience. Recall Galileo.

Next Class

The British Empiricists Kant Maybe Mill and Wolstonecraft.