Download Rationalist Epistemology

Rationalist Epistemology
Plato and Descartes
Readings, Quiz 3
DP Ch 2 "Rationalist Epistemology" and "The
Philosophy of Plato"
DP Ch 7 "Ancient Greek Moral Philosophers" (on
Plato's ethics only)
DP Ch 9 "Political Philosophy" (on Plato's political
philosophy only)
DP Ch 10 "Plato and Freud"
CB The Allegory of the Cave
Meno (all) Online
Epistemology is the branch of philosophy that investigates the nature,
source, and limits of KNOWLEDGE. You can easily figure out what
"epistemology" means if you know a little Greek. "Episteme" is the
Greek word for "knowledge," and you already know what logos
means.
The following are all typical epistemological questions:
1. Is there any knowledge in the world so certain that no
reasonable person could doubt it?
2. Is there any secure basis for our future expectations,
or is it just a matter of crossing our fingers and hoping
for the best?
3. Does science explain — does it help us to understand
anything? or does it merely describe?
4. What, if anything, is the contribution of the senses to
Ancient Greek Rationalism: The first rationalist in Western
Philosophy was the ancient Greek philosopher Plato. Plato
was monumentally important in the history of philosophy.
Quiz 3 will focus entirely on Plato's philosophy.
Continental Rationalism is a movement in epistemology in
the modern period of philosophy (when was that? See the
Chronological List of Western Philosophers). So Plato was
a rationalist, but not a "Continental Rationalist." The major
figures of Continental Rationalism are Descartes (the focus
of Quiz 4), Spinoza, and Leibniz. All the Continental
Rationalists are rationalists in the broad sense; i.e., all
share the basic rationalist viewpoint with Plato
Rationalist Epistemology
Rationalism in epistemology is the
view that knowledge does not
come from the senses. According
to rationalists, the paradigm of
knowledge is mathematics.
Rationalists say knowledge comes
primarily or solely from reason, or
from intuition, or that we possess
it innately (from birth).
In contrast, empiricist epistemology is the view that
knowledge does come primarily or solely from the senses.
But we will talk about this later.
Metaphysics
Metaphysics is the branch of philosophy that
investigates the general nature of being or reality,
especially the being of the sensible world, God, freedom,
and souls.
The word "metaphysics" is usually synonymous with the
word "ontology." The following are all metaphysical (or
ontological) questions:
1.
What is reality?
2.
What do real things have that
unreal things lack?
3.
Are some kinds of things
(e.g., material things) more
real than others (e.g.,
concepts)?
4.
Does a tree falling in the
forest if no one is around
make a real sound?
5.
Is God real?
6.
Is the mind a separate
substance? If so, how does it
relate to matter? What is
matter?
7.
Does human freedom exist?
If so, what is it?
Rationalism
A priori truths
A statement is true or false a priori if no observation or
experiment is required to determine if it is true or false.
Examples of a priori statements are mathematical
assertions, statements true or false by definition, and
logical truths and falsehoods. We “just know” when some
claims are a priori true or false. For example, we “just
know” that the same statement cannot be both true and
false in the same sense at the same time (a rule of logic
called the law of non-contradiction).
a posteriori truths
A statement is true or false a posteriori if
observation or experiment is required to
determine if it is true or false; we don’t “just
know” it. Examples of a posteriori statements are
statements about the world, e.g., “Dogs are
carnivores” or “Ottawa is the capitol of Canada.”
Raphael’s “School of Athens”
Plato and Aristotle
Plato’s Meno
The dialog takes place around 402 BC, about 3 years before
Socrates’ trial and execution. The character Anytus was later
one of Socrates’ main accusers at the trial.
Meno asks, “Can virtue (arete) be taught?”
Meno
• Phase I of the Meno (70-80) has Socrates asking
Meno for a general definition of arete, since as
Socrates points out, we can’t figure out if arete
can be taught if we don’t have a clear idea what it
is. Note Socrates is looking for a general, or
formal definition of arete, not just examples or
instances of it. Socrates wants to know what all
the examples of arete have in common: the
“essence” or “form” of arete.
• Socratic Paradox
The statement of the so-called Socratic paradox appears at
77c-78b. The Socratic paradox is Socrates’ apparent claim
that arete is a kind of knowledge, and vice a kind of
ignorance. It is a paradox (an odd or unusual claim)
because people usually think a person can know the good
and still fail to do it. That is, people usually think that arete
is more than a matter of knowing; it is, people think, also a
matter of willing. Christians, for example, think of sin as a
matter of knowing what one should do and not doing it.
But if virtue is knowledge, as Socrates says, anybody who
really knew the good would automatically be good. If
Socrates is right that arete is a kind of knowledge, it would
be impossible to know the good and not be good.
Phase II
• Begins with Meno’s challenge to Socrates at 80d-e: if you
don’t know what arete is already, you can’t even look for
it, because if you don’t know what it is already, then even
if you look, you won’t know when you’ve found it.
Alternatively, if you know what it is you don’t need to
look for it.
• Socrates claims that knowing is a kind of remembering
(i.e., you do know what arete is already), and Socrates’
famous demonstration of the ignorant slave boy
“remembering” geometry as a result of Socrates’
questioning.
Phase III (86c-end)
•Socrates reluctantly agrees to explore whether virtue can be taught. He proposes a
strategy: first determine if virtue is a kind of knowledge. Then if it is, we’ll conclude it
can be taught. And if virtue isn’t knowledge, we’ll conclude it can’t be taught.
•In 87-89c, Socrates points out there are teachers for medicine, horsemanship, etc. and
everybody agrees that these are genuine teachers, whereas people disagree about
whether the Sophists really do teach virtue. Maybe this is because virtue cannot be
taught.
•Anytus now appears. Anytus mistakenly thinks that because Socrates has mentioned
the Sophists as possible teachers of virtue, that Socrates must approve of the Sophists.
(Anytus does not understand that Socrates was being ironic.) Anytus is vehemently
opposed to the Sophists. Socrates agrees with Anytus about the Sophists; but Socrates
insists that Anytus give reasons for his opposition to them. Anytus can’t give any
reasons. Socrates keeps asking until Anytus walks away furious, thinking he has been
“dissed.”
• (Phase III) In the last pages of the Meno, none of the early questions — whether
virtue is knowledge, whether virtue can be taught, the nature of virtue itself — are
answered.
• But we arrive at some clarity about an unexpected issue: the nature and
importance of knowledge. Knowledge is justified true belief. You need the
justification — you need to be able to explain and support your true belief —
because otherwise knowledge “flies away” like the statues of Daedalus.
•Plato doesn’t point this out explicitly, but it’s clear we’ve just seen a perfect
example, in Anytus, of the shortcomings of unjustified true belief.
Plato’s Epistemology
•Plato studied geometry with the Pythagoreans. He was amazed that
geometrical statements — such as “The area of the circle is πr2” — were true of
all circles (universally) and were always true (unchanging).
•Math demonstrates that universal and unchanging knowledge exists. For
Plato, universal and unchanging knowledge is clearly better (“higher”) than
particular and changing (sensory) knowledge.
• In fact, for Plato, so-called “knowledge” from the senses, which is particular
and changing, shouldn’t really be called knowledge at all.
Plato’s metaphysics
• For Plato, as for us, all knowledge is intentional, i.e., knowledge of something. If the geometers
know something, then, there must be something they know. The unchanging universal realities
known through math — such as “the circle” — must exist. That is, math knowledge reveals a world
of universal and unchanging realities. Plato calls these realities the Forms.
What are Forms?
• Forms are archetypes or models. Things in the world of the senses “imitate” or “participate in”
Forms.
• Plato reasons that there must be Forms for every thing that has being: trees, rocks,
stars, circles, etc. Plato is especially interested in Forms of moral and aesthetic characteristics such
as Beauty (the thing all beautiful things have), Courage (the thing all courageous people have),
and Goodness (the highest Form).
• Forms are changeless. Things in the world of the senses change; they go in and out of being.
The Forms, according to Plato, do not change. For example, the Form of Treeness does not lose its
leaves, or die. Thus, for Plato, the Forms have more reality or being than things in the world of the
senses. Conversely, a thing has less reality the farther removed it is from its Form.
What are Forms?
• Forms are mind-independent and objective realities. They are not
just mental constructs
• Forms are non-physical entities, perceivable by the mind or reason
but not by the senses.
• Forms are Eternal. Though individual circles or cats may perish.
“Circle” itself, or “Cat” itself never perishes.
• Forms are divine.
• Forms are the true objects of knowledge.
• Everything that exists is what it is because it participates in the
forms.
• The forms are Plato’s answer to the central questions of
metaphysics, epistemology and ethics.
Allegory of the Cave
Activity
Make a drawing of Plato’s Cave which
includes as many elements as you can find.
Then interpret what you think the elements
symbolize using the Analogy of the Divided
Line.
Plato’s Ethics
• A person is good, more courageous, etc. depending
on how much their actions participate in the form of
Good or Courage
• A person becomes good to the extent that their
reason is in control of the other elements of their
soul.
• The better a person can reason
(simultaneously coming closer to
apprehension of the ultimate Form, the Form
of the Good), the better (and more human) a
person is. The most realized, highlydeveloped, rational, and real person is the one
who knows Goodness itself.
The Challenge of Glaucon
• In Plato’s major work The Republic, Glaucon
challenges Socrates to prove that being a just or
good person is in your best interest. He narrates
the story of the Ring of Gyges.
Tripartite Theory of the Soul
For Plato there are three parts of the soul:
• Reason is the faculty of the soul that
can do math-type, abstract thinking,
and thus apprehend the Forms.
• Spirit (Thymos) Dignity, honor,
aggressive energy
• Appetite is the desire for food, sex,
drink. Bodily pleasures.
Socrates’ Answer to Gaucon
• A well-ordered, good, soul is one in which Reason rules.
Such a soul, at its best, exercises virtue effortlessly as a
result of the transformative experience of Goodness
itself. Such a soul is psychically integrated, happiest,
sanest, most moral, most free, and most fully human.
Plato’s answer to Glaucon, then, is that one should
strive to be a moral person because being moral, being
reasonable, being happy, being sane, being free, and
being fully human are all the same thing.
• One whose soul is not well-ordered, not ruled by
reason, is psychically dis-integrated, unhappy, immoral,
a slave to passion, less than human. The psychically
dis- integrated soul is sick; it is afflicted with akrasia
(the origin of the English word "crazy").
Political Philosophy
Plato thinks the State is also composed of
three parts:
• The class of those who reason well
(Philosophers) - Reason
• The Guardians (soldiers) – Spirit
• Artisans/craftspeople/business people Appetites
Just State
A just state is a state with an analogous
structure to a just individual. It should be
ruled by philosophers (the most rational)
with the aid of the guardians (the most
spirited) over the largest sector – the
business/craft/manufacturing class.
Unjust State
• A badly-ordered state is in chaos. Allowing
aggressive soldiers (e.g., Klingons) or appetitive
craftspeople (e.g., Ferengi) to rule the state is like
letting the inmates run the asylum. Such a
government makes it difficult for its citizens to
live fully human lives. People must perform jobs
they’re not suited for, so everyone is personally
unhappy. Unwise, shortsighted rulers are not wise,
so there is rebellion and conflict within the state.
Reasonable people will be persecuted, even
executed (as Socrates was).
Why Art Should be Banned from
the Just State
Identify the arguments Plato gives why art
should be banned from the Republic.
René Descartes (1596—1650)
Reading
• DP Ch 2 "Rene Descartes'
Rationalism"
• DP Ch 4 "Dualism" ( on Descartes
only)
• Meditations I, II, VI Online
Group Questions
1. What is Descartes’ ultimate goal in the
“Meditations”?
2. The question of whether or not Jupiter has
moons is an astronomical matter; it’s not a
question of theology or Scripture. So why did
the Church find this discovery alarming?
The following questions refer to the Meditations:
3. What is Descartes dream argument. What
exactly does it prove?
4. What is Descartes’ Evil Genius Argument?
How does it go farther than the dream
argument in its skepticism?
5. What a priori truth does Descartes find in
Meditation II and why is it a priori?
6. What is Descartes argument for the
existence of God?
7. In Meditation VI, Descartes finally concludes
that he has knowledge of the world external
to his mind. Why? What sort of knowledge
of the external world does he get? Why was
the Church happy with Descartes’
8. What is Descartes' argument of the wax?
What does Descartes think it proves?
9. What is Cartesian Dualism?
Outline of the Meditations
Meditation I
• Methodological (Systematic Doubt)
Argument From Illusions
Dream Argument
Evil Genius Hypothesis
Outline of the Meditations
Meditation II
• “I think, therefore I am” — cogito ergo sum.
• Cartesian Dualism – Mind and Body are
distinct substances.
• Wax Argument. Notions of Substance and
Identity are innate
Meditations III-V
• A priori argument that God exists (My idea of
perfection had to come from a perfect being)
• God is not a deceiver. Therefore Math knowledge
is indubitable
• Therefore our knowledge of the sensible world is
guaranteed at least insofar as our sensations of
primary (mathematical) qualities are concerned.
Empiricist Epistemology,
Locke, Berkeley and Hume
• Empiricism stresses the power of a posteriori
reasoning — reasoning from observation or
experience — to grasp substantial truths about the
world.
• When a priori ideas conflict with the a posteriori,
the a posteriori wins, according to empiricism.
• Empiricism is usually opposed to rationalism
- the view that reason rather than sensation or
observation is the source of knowledge.
• Empiricists tend to see modern science as the
paradigm of knowledge. The empiricist approach
is hands-on, down-to-earth. Empiricists urge us to
trust our senses, observe the world carefully,
perform experiments, and learn from experience.
• So, empiricists would say, we should be
suspicious of explanations that make reference to
non-observable entities such as gods, souls,
immaterial minds, and other metaphysical
concepts not verifiable by the senses.
• British Empiricism was a movement in
epistemology in the modern period of
philosophy. The major figures of British
Empiricism are Locke, Berkeley, and
Hume. The ancient Greek philosopher
Aristotle is usually considered a forerunner
of modern empiricism. For example, he
criticized Plato’s very non-empirical notion
of transcendental forms.
British Empiricism
The “British Empiricists” were:
1. John Locke (1632-1704)
2. George Berkeley (1685-1753)
3. David Hume (1711-1776)
John Locke
• Blank Slate Nihil in intellectu quod prius
non fuerit in sensu. (“There’s nothing in the
intellect that wasn’t previously in the
senses.”)
• According to Locke, the mind at birth is a
tabula rasa (blank slate).
• No ideas are innate. Locke applies Ockham’s
Razor to innate ideas: we can explain everything
we know without invoking innate ideas (our
senses are enough); so innate ideas are
unnecessary.
• Metaphysical nominalism: only particular things
exist (not concepts, abstractions, Forms, etc.)
• Psychological atomism: according to Locke, the
ultimate building blocks of knowledge are simple,
discrete perceptual units (his “simple ideas”).
• “Simple” here means “from a single sense,” and
thus not able to be broken down into smaller
constituent parts.
• Three kinds of complex ideas are built from
simple ones:
-compounds (“red house” = "red" + "house");
- relations (“taller than,” “loves”)
- abstractions which lead us to general ideas, e.g.,
“blue”, “dog.”Abstraction” is the name of a mental
process by which general ideas are generated from
particular ideas.
• “Representative realism” is Locke’s view that we
experience objects indirectly through
“representations”.
• The mind represents the world, but does not
duplicate it. Descartes also held this view.
• Representative realism is opposed to naïve
realism, the view that the mind literally duplicates
or “mirrors” external reality.
• Primary qualities are measurable using numbers
(e.g., size, weight). They represent the world as it
is “objectively”, the same for everyone.
• Secondary qualities result from the interaction of
sense data with our sense organs, i.e., they are
“subjective” in the sense that the powers that
produce them (corpuscles interacting on our
senses) are nothing like the ideas themselves.
The Problem of Substance
• Both Descartes and Locke conclude there’s a real
substantive world “out there” that has certain
qualities (the primary qualities). The primary
qualities are qualities of the underlying
“substance” (from sub (under) and stance
(standing)).
• But if Locke is committed to the view that all
knowledge comes from the senses, he can’t allow
that we know substance, since we have no
sensation of substance (we have sensations only of
• the qualities). Thus an essential element of
Locke’s empiricist philosophy remains
unsupported (and unsupportable) by
Locke’s empiricist principles.
George Berkeley
George Berkeley held all the following views:
• Locke did not apply Ockham’s razor vigorously
enough. Berkeley applies Ockham’s razor to
Locke’s notion of substance.
• Experience is the source of most knowledge
(except knowledge of self and knowledge of God).
So Berkeley is an empiricist, but with an
interesting idealist twist.
•
•
•
•
•
All and only perceptions (qualities) are
experienced.
According to Berkeley, all experience is
conscious, or, in other words, mental; we
experience only “ideas”.
Thus we never have direct experience of things
themselves.
Thus our experience does not support the view
that there are things outside the mind at all. Socalled “material” things are really just clusters of
ideas.
Thus, there’s no way to distinguish primary and
secondary qualities. All qualities are secondary
(the object for me). Measurable qualities (so-
called “primary” qualities) are just as
“subjective” as color and taste, since all qualities
are “in my head”.
• Thus, to be is to be perceived (esse est percipi).
• But our experiences appear to be consistent with
the experience of (supposed) “other people”.
Also, things appear to exist continuously; they
don’t appear to flash in and out of being
depending on whether they’re being perceived.
What accounts for this coherence and continuity
of experience?
• This inter-subjective agreement and apparent
continuity of perception is due to the watchful
• attention of God – the great perceiver who never
looks away. We can thus derive knowledge of the
existence of God from a transcendental argument
(God must exist for our experience to be what it
is).
• Inconsistencies in Berkeley. God is not something
that is perceivable but Berkeley is an empiricist
and empiricists say we can only have knowledge
of what we perceive.
• Berkeley also accepts the Cartesian view that we
know our own existence, our Self innately. But
empiricists aren’t supposed to believe in innate
ideas.
David Hume
Radical Empiricist
Please respond to the following selected
question you have been assigned. Create a
legible preferably typed document
answering the question. The document will
be shown to the class.
1. What is Berkeley’s argument that there is no
distinction between primary and secondary
qualities?
2. Explain Berkeley’s view that physical objects
are nothing more than sense data. Give an
analysis of a couple objects as fully as you can
in terms of sense data.
3. Explain the source of sense data, for Berkeley.
How is this different from Locke’s view? How
is it similar to Locke’s Evil Genius Hypothesis?
4. Explain how some of Berkeley’s beliefs seem to
contradict his empiricism.
David Hume
5. Explain the characteristics of analytic and
synthetic statements. How is this distinction
used by Hume to dispose of all
metaphysical knowledge?
6. Explain Hume’s destruction of the concept
of “Self.”
7. Explain Hume’s and the Positivist’s
destruction of the concept of causality.
8. Explain the Positivist’s destruction of the
concept of substance. How would the
Positivist analyze the statement, “There is
a car in the garage?”
Immanuel Kant
•
The philosophy of Immanuel Kant (17241804) is sometimes called the “Copernican
revolution of philosophy” to emphasize its
novelty and huge importance.
• Kant synthesized (brought together)
rationalism and empiricism. After Kant, the old
debate between rationalists and empiricists
ended, and epistemology went in a new
direction.
• After Kant, no discussion of reality or
knowledge could take place without awareness
of the role of the human mind in constructing
reality and knowledge.
Immanuel Kant
Summary of Rationalism
1. Don’t trust senses, since they sometimes
deceive; and since the “knowledge” they provide
is inferior (because it changes).
2. Reason alone can provide knowledge. Math is
the paradigm of real knowledge.
3. There are innate ideas, e.g., Plato’s Forms, or
Descartes’ concepts of self, substance, and
identity.
4. The self is real and discernable through
immediate intellectual intuition (cogito
ergo sum).
Kant says rationalists are sort of right about
(3) and (4) above; wrong about (1) and
(2).
Summary of Empiricism
1. Senses are the primary, or only,
source of knowledge of world.
Psychological atomism.
2. Mathematics and a priori claims deals
only with relations of ideas
(tautologies); gives no knowledge of
world.
3. No innate ideas.
4. Hume — there’s no immediate
intellectual intuition of self. The
concept of “Self” is not supported by
sensations either.
5. Hume — no sensations support the
notion of necessary connections
between causes and effects, or the
notion that the future will resemble
the past.
Kant thinks empiricism is on the right track re (1),
sort of right re (2), wrong re (3), (4), (5).
Transcendental Categories of the
Understanding
• Kant concludes after a long series of
arguments in his great work, The Critique of
Pure Reason, that there must be innate
structures of the human mind that filter or
interpret or structure the input of the senses.
• Though innate these structures are not
innate in the sense that Plato and Descartes
mean.
• These categories include, such things as Space,
Time, Substance, Cause and effect, Self, Unity
(Identity).
• The input of the senses is filtered through these
structures in such a way that we must perceive the
world in terms of substance, cause and effect, etc.
(If we have rose colored glasses on, we must
perceive the world as rose colored.)
• We can never know the world as it is in itself,
without being filtered through the categories. The
world as it really is, Kant calls the noumenal
world.
• We can only know the world as we perceive
it (through the filters). Kant calls the world
as perceived, the phenomenal world.
• Both the senses and the mind (reason)
contribute to knowledge. “Thoughts without
content (sense experience) are empty,
intuitions (sense experience) without
concepts (categories of understanding) are
blind.”
• Kant’s lasting influence: Philosophy was
indelibly changed by Kant’s powerful idea
that the mind is not a passive receptacle of
sense data per the empiricists, but actively
shapes our experience of the world. Any
account of knowledge and perception must
include the fact that our minds shape what
we experience.