Ch5ppt velasquez12

CHAPTER FIVE: THE SOURCES OFCHAPTER FIVE: THE SOURCES OF
KNOWLEDGEKNOWLEDGE
P H I L O S O P H YP H I L O S O P H Y
A TEXT WITH READINGSA TEXT WITH READINGS
1212thth
EDITIONEDITION
Manual VelasquezManual Velasquez
Chapter 5: “The Sources of Knowledge”Chapter 5: “The Sources of Knowledge”

Outline of Topics in Chapter 5Outline of Topics in Chapter 5
• 5.1 Why Is Knowledge a Problem?
• 5.2 Is Reason the Source of Our Knowledge?
• 5.3 Can the Senses Account for All Our
Knowledge?
• 5.4 Kant: Does the Knowing Mind Shape the
World?
• 5.5 Does Science Give Us Knowledge?
CHAPTER FIVE: THE SOURCES OF KNOWLEDGECHAPTER FIVE: THE SOURCES OF KNOWLEDGE

EpistemologyEpistemology
• One of the fundamental branches of philosophy
is epistemology, the study of knowledge.
– Specifically, epistemology deals with the nature,
sources, limitations, and validity of knowledge.
– Epistemological questions are basic to all other
philosophical inquiries.
– This chapter focuses on the question of how true
knowledge is acquired—its sources or bases.
– The next chapter examines the nature of true
knowledge and truth.

5.1 Why is Knowledge a Problem?5.1 Why is Knowledge a Problem?
• The problem of knowledge arises very clearly when we
think of the fact that our very identities are constituted by
our memories of that past—of parents, of the home one
grew up in, etc. How do we know our memories are
true?
• The problem of knowledge also arises when we ponder
how in the past century history some researchers claim
that the white race is genetically superior to the black
race.
• More recently, we can see it surfacing in the controversy
surrounding repressed or recovered memories.

Acquiring Reliable Knowledge:Acquiring Reliable Knowledge:
Reason and the SensesReason and the Senses
• A central problem in this chapter is how reliable
knowledge is acquired. There are two main
alternatives:
– Rationalism is the viewpoint that insists
knowledge arises from reason, without aid
from the senses.
– Empiricism contrasts with rationalism in
holding that knowledge arises from the
senses.

The Role of MemoryThe Role of Memory
• The controversy over recovered memories
suggests that memory might also play an
important role in knowledge.
– Habit memory is our ability to remember how to do
something that we learned in the past, such as how to
ride a bicycle or how to ski
– Personal memory is our ability to bring into our
present consciousness a representation of events that
we personally and directly experienced in the past.
– Factual memory is our memory of all the facts that
make up our knowledge of the world.

Memory is not BasicMemory is not Basic
• Memory is not an independent source of
knowledge because any knowledge we have in
memory had to be acquired from some other
source, such as sense experience or reason.
– For example, my factual memory does not bring any
new knowledge to me but merely preserves
knowledge that I acquired through some other source.
– Thus, in the sections that follow we will discuss sense
perception and reason as sources of knowledge, but
not memory.

5.2 Is Reason the Source
of Our Knowledge?
• Rationalism is the belief that reason, without the
aid of sensory perception, is capable of arriving
at knowledge, and undeniable truths about the
world.
– When rationalists claim that knowledge is based on
reason rather than perception, such as seeing and
hearing, they mean that we do not rely on sensory
experience for all of the fundamental knowledge we
have.
– Rationalists often point to mathematics and logic as
examples of reason-based knowledge.

Mathematics and LogicMathematics and Logic
• Mathematics and logic are examples of a priori
knowledge, i.e., knowledge that is known
independently of sense perception and that is
necessarily true and indubitable.
– The mathematician does not need to make
observations to see whether her theories and
theorems are true.
• And yet all precise science depends on mathematics.
– Likewise, the laws of logic (such as “No proposition
can both be and not be true at the same time”) are
not established by observation.
• Yet they underlie all our reasoning processes.

An Eastern RationalistAn Eastern Rationalist
• The Indian philosopher Shankara (788–822),
was a rationalist who held that our knowledge of
ultimate reality is not acquired through our
senses but through reasoning and meditation.
• Sublation is a central idea in Shankara’s
philosophy .
– Sublation is the process of correcting an error about
reality when it is contradicted by a different but more
correct understanding of reality.

SublationSublation
• Shankara argues that hallucinations, dreams,
mirages, and other illusions give rise to errors
that we “sublate” when we see that they are
contradicted by other things our senses show us
in the world around us.
• Everything in the world around us that we
perceive with our senses can also be sublated:
– Through the study of the Hindu Scriptures, through
reasoning, and through meditation we come to know
the ultimate reality, which he called Brahman.

Descartes, the RationalistDescartes, the Rationalist
• Perhaps the most famous Western rationalist
was the French philosopher, Rene Descartes
(1596-1650).
• Descartes’ rationalism can be viewed as a kind
of three step journey of the mind.
1. It begins with skepticism and doubting –especially
regarding the senses.
2. It establishes a foundation of what can’t be doubted.
3. It builds an edifice of knowledge on this foundation.
• None of the three steps involves the senses.

Descartes’ Starting PointDescartes’ Starting Point
• The 16th
and 17th
centuries centuries were a time
marked by a profound skepticism and doubt
regarding established religious doctrines and
time-honored scientific opinions.
– Descartes shared this doubt, but paradoxically used it
methodically to discover a foundation of indubitable, a
priori truths which could serve as the basis for all
knowledge.
– He looked to geometry (of which he was one of the
pioneers) to provide a model for good reasoning.

Doubting EverythingDoubting Everything
• Descartes began by searching for reasons to
doubt all of his most basic beliefs (including his
sensory beliefs, and those regarding the
physical universe).
– He focused on the evident fact that it was possible he
was dreaming.
• If this was the case, everything he sensed might be an
illusion.
• He also believed that it was at least possible that his mind
was being deceived by an evil genius or god.
• If this were true, he couldn’t’ trust any of his knowledge.

I am, I existI am, I exist
• Still, even if he were dreaming or was being
deceived, he was at least thinking, so something
remained that he couldn’t doubt: the fact that
was thinking and thus existed!
• “Doubtless, then, I exist, since I am deceived; and, let
him deceive me as he may, he can never bring it
about that I am nothing, so long as I shall be
conscious that I am something. So that it must, in
fine, be maintained, all things being maturely and
carefully considered, that this proposition, I am, I
exist, is necessarily true each time it is expressed by
me, or conceived in my mind.” (326)

Clarity and DistinctnessClarity and Distinctness
• Descartes believes that what makes him certain
about the idea that “I think, I exist” is the clarity
and distinctness with which he apprehends this
idea.
– When an idea is clear we know exactly what it is, that
is, when we know its essential properties or essential
nature
– When we have a distinct idea of something when we
can readily distinguish it from other things.
– For Descartes, clarity and distinctness are the marks
of certitude.

The Piece of WaxThe Piece of Wax
• Through his reflection on the piece of wax (see
pg. 327), Descartes argues that what we know
clearly and distinctly about physical bodies is
known through the mind – and not the senses.
– Descartes reasons that our minds know that as it
melts, the wax remains the same bodily thing
although to our senses all of its qualities have
changed.
– Thus, our knowledge of what the wax itself is—an
enduring physical body—does not derive from the
senses or the imagination, but from the mind alone.

Strong RationalismStrong Rationalism
• Descartes’ is not denying that we acquire some
ideas through our senses.
– He notes, for example: “But if I hear a noise, if I see
the sun, or if I feel its heat, I have all along judged that
these sensations proceeded from certain objects
existing out of myself.” (328)
– However, our knowledge of the essential nature of the
body that gives off sounds or that glows like the sun or
that emits heat, is acquired by the mind alone.
– This extreme or strong rationalism is also evident in
Descartes’ approach to knowing God.

Knowledge of GodKnowledge of God
• Descartes uses a version of the ontological
argument to prove God’s existence – and thus to
ratify the non-deceptive nature of his
foundational knowledge.
– He claims that he has the idea of God, a supremely
perfect being.
– He could not have produced the idea of a perfect
being, and could not have acquired it through the
senses; only God could have put it into his mind, so
God must exist.
– Because God is good, He does not deceive, so we
can rely on the powers of knowing He has given us.

Innate IdeasInnate Ideas
• Rationalists such as Plato, Descartes, Leibniz,
and the Indian Jain philosophers believe that the
ideas and truths that the mind knows without
relying on its senses are innate.
– Innate ideas are ideas, concepts or tendencies we are
born with; they are not acquired through experience.
– The basic idea is that some ideas, such as pure,
idealized mathematical constructs (the line, the point)
must be innate features of the mind, as they could not
have been acquired via experience.

Innate Ideas in theInnate Ideas in the MenoMeno
• In the Meno, Plato provides a famous example
of a person—a slave boy in this case—
becoming aware of the innate ideas about
geometrical figures he had in his mind but did
not consciously know he had.
• Socrates helps the slave boy remember
something he had never learned!
– Explain how the story makes a case for innate ideas.
(330-331)

Native IntelligenceNative Intelligence
• Most rationalists do not accept Plato’s
assumption that we must have preexisted in a
more perfect world.
• Instead, they argue that the ideas are basic
features of the mind. Thus Descartes says:
– “[W]e come to know them [innate ideas] by the power
of our own native intelligence, without any sensory
experience. All geometrical truths are of this sort —
not just the most obvious ones, but all the others,
however abstruse they may appear.”(331)

Three Kinds of Innate IdeasThree Kinds of Innate Ideas
• Descartes claimed that when we call an idea
innate we are not saying it is always there before
us. in our conscious awareness.
– Rather we mean that we have within ourselves the
faculty of summoning up the idea.
– When we summon up an innate idea, we become
aware of it as if we were recalling a memory.
– Descartes claimed we had innate ideas of three
fundamental kinds of realities: material bodies, God
and the mind.

Dispositional Innate IdeasDispositional Innate Ideas
• While Gottfried Leibniz (1646–1716) agreed with
Descartes that we our most basic ideas and
truths are innate and not acquired from
experience, he did not think these ideas were
fully formed “actualities” in the mind.
– Rather they are dispositions or tendencies in the
mind. He used a powerful metaphor to express this:
• “If there were veins in a block of marble which marked out
the shape of Hercules rather than other shapes, then that
block would be more determined to that shape and Hercules
would be innate in it, in a way, even though labor would be
required to expose the veins and to polish them into clarity,
removing everything that prevents their being seen.” (333)

Jainism and Innate IdeasJainism and Innate Ideas
• The Indian philosophy of Jainism, which
originated several centuries before Christianity,
has also embraced a version of innate ideas.
– Philosophers of the school of Jainism hold that even
before our senses perceive an object, we already
have the knowledge of that object in our minds.
• When we see an object, our perception of the object merely
serves to uncover the innate knowledge of that object that we
already had within us.
• The philosophers of Jainism hold that every human being
carries within his or her mind a complete knowledge of
everything in the universe.

5.3 Can the Senses Account for All5.3 Can the Senses Account for All
Our Knowledge?Our Knowledge?
• Empiricism offers a conception of knowledge
that contrasts with rationalism.
– Empiricists claim that knowledge is a posteriori, that
is, it arises from sense experience, and that there is
nothing in the human mind contains nothing except
what experience has put there.
– John Locke, George Berkeley, David Hume, and the
Indian philosophers Charvaka and Nyaya have all
embraced versions of empiricism.

Locke’s EmpiricismLocke’s Empiricism
• In West, the English philosopher John Locke
(1632–1704) launched the first systematic
attack on the rationalist belief that reason alone
could provide us with knowledge.
• Three aspects of Locke’s empiricism are worth
considering:
– His theory of Ideas;
– His distinction between primary and secondary
qualities;
– His account of how we know reality independently of
our minds.

Locke’s Theory of IdeasLocke’s Theory of Ideas
• Locke argues that none of our ideas are innate.
– The mind is a kind of tabula rasa or blank slate, which
the senses furnish with ideas.
• He distinguishes between simple ideas, such as
sweetness, or redness, and complex ideas,
which the mind constructs from repeating and
combining the simple ideas:
– “In this faculty of repeating and joining together its
ideas, the mind has great power in varying and
multiplying the objects of its thoughts, infinitely
beyond what sensation or reflection furnished it with.”
(337)

Ideas and RealityIdeas and Reality
• For Locke, knowledge then arises from sensory
sensory experience.
• This raises a question: what is the relationship
between our ideas and reality, such as physical
objects?
• Locke can respond to this question in two
general ways:
1. He can claim that reality is indistinguishable from our
ideas of it: what you see is what you get.
2. He can claim that reality and our ideas of reality that
we experience are separate.

Physical Objects ExistPhysical Objects Exist
• Locke takes the second route, arguing that
physical objects actually exist, outside of us.
• He expresses this with the intuition:
– “I can no more doubt, whilst I write this, that I see
white and black, and that something really exists that
causes that sensation in me, than that I write or move
my hand.” (338)
– Locke uses the distinction between primary and
secondary qualities to further clarify what objective
reality is.

Primary versus SecondaryPrimary versus Secondary
QualitiesQualities
• Primary qualities are those aspects of things that
can be measured and quantified, such as size,
shape and weight.
– Primary qualities are “in” the things we perceive.
– This is what the real world consists of.
• Secondary qualities are the subjective aspects
of things, such as colors and tastes.
– They are not “in” the object but are sensations.

The Lockean Bottom LineThe Lockean Bottom Line
• So, Locke concludes that we know how things
are because our ideas of primary qualities
actually resemble the primary qualities of objects
in the external world.
– For example, if we experience the tree as being a
certain height, we can trust that idea to represent how
the tree really is.
– If we experience it to have a certain shape, we can
trust that idea to represent how the tree really is

Problems for Locke’s AccountProblems for Locke’s Account
• However, even with the primary/secondary
distinction in hand, it is unclear that Locke can
explain ,within the confines of his theory, the
claims that a) some of our ideas are
independent of the real world; and b) and that
we have knowledge when our ideas resemble
that world.
– If all we are aware of is our ideas, how can we know if
they resemble anything separate from them.
– Can we even know that there is an external world?

Berkeley’s SubjectiveBerkeley’s Subjective
EmpiricismEmpiricism
• George Berkeley (1685-1753) offers a more
radical version of empiricism that Locke’s.
• He opts for the first of Locke’s two options --
reality is indistinguishable from our ideas of it:
esse est percipi-- “to be is to be perceived”
– He denies Locke’s claim that primary qualities are
real.
– In the hopes of avoiding solipsism, he offers his own
account of knowledge, making use of the notion
God’s Mind.

Primary Qualities ExistPrimary Qualities Exist
Only in the MindOnly in the Mind
• George Berkeley agrees with Locke that
secondary qualities are purely mental, but
argues against his claim that our ideas of
primary qualities are accurate copies of the
qualities of external material bodies.
1. Since an idea can only be like another idea primary
qualities must be ideas.
2. Because ideas can exist only in the mind, primary
qualities can exist only in the mind.
3. Therefore, primary qualities are not qualities of
external material bodies.

External Objects do not ExistExternal Objects do not Exist
• Berkeley offers an argument against Locke’s
claim the external world must exist as the cause
of our sensations.
– He argues that just as our dreams do not need to be
caused by external objects, so, too, the sensations
we have need not be caused by anything at all.
– Against the apparently obvious reply that we know
objects exist because we can touch them, see them,
etc. Berkeley points out that we cannot use our
senses to verify external objects cause our
sensations, since we perceive only the sensations in
our minds.

Is Berkeley a Solipsist?Is Berkeley a Solipsist?
• Because Berkeley claims that nothing but minds
and their sensations exist, he is vulnerable to the
charge of solipsism.
– Solipsism is the position that only I exist and that
everything and everyone else is just an idea in my
subjective consciousness, so that what is real is
whatever seems real to me in my own private world of
ideas.
– Why is Berkeley vulnerable to this charge and how
does he attempt to respond to it?
– What new problems does his response create?

The God MoveThe God Move
• Berkeley attempts to avoid solipsism by
appealing to an outside source that maintains
and is responsible for our ideas about the world
around us: God.
– Because God holds the world in His Mind, things
continue to exist for us and others even when we do
not perceive them.
– That’s because God continues to perceive them and
makes them available to me when I look around.
• What objections does the text bring up regarding
Berkeley’s position? (344-345)

Hume’s Skeptical EmpiricismHume’s Skeptical Empiricism
• David Hume (1711-1776) pushes Locke’s and
Berkeley’s empiricism to the conclusion of a
thorough-going skepticism.
– He denies the possibility that we can have certain
knowledge about much of what we all take for
granted, including the existence of the external world,
and the real causes of phenomena.
– He argues instead that our assumption of these
realities is built on custom and habit.

Perceptions of the MindPerceptions of the Mind
• Hume begins by claiming that all the contents of
the mind can be reduced to those given by the
senses and experience.
• He calls these perceptions, and distinguishes
between two kinds, based on degrees of
liveliness and vivacity:
– Impressions, such as perceived colors, feelings of hot
and cold and passions, are more lively.
– Ideas, such as thoughts and abstract notions – these
are less lively.

No Ideas Without ImpressionsNo Ideas Without Impressions
• Hume claims that every idea we have in our
heads has to come from some earlier sense
impression.
– Thus, Hume’s general principle: Any claim to
knowledge must be based on sense impressions.
– But what about ideas we have of things we’ve never
perceived with our senses, such as a golden
mountain or a pink elephant?
• Hume answers that our imagination combines impressions
we earlier acquired from our senses.: “When we think of a
golden mountain, we only join two consistent ideas, gold and
mountain, with which we were formerly acquainted.” (346)

Hume and the Idea of CauseHume and the Idea of Cause
• Hume uses his general principle to prove that we
have no knowledge of real causes.
– Most of us believe that when we assert “X causes Y,”
there is some kind of real connection between them,
some kind of “power” or force by which the cause
really exerts its causality on its effect.
– How does Hume show that we lack this knowledge,
and what alternative account of our belief in causation
does he offer?

Habit Not KnowledgeHabit Not Knowledge
• Hume’s argument against cause is that while we
perceive one thing happening before another
thing, such as a match striking a match box and
then catching fire, we never perceive any real
connection or power.
– He argues that our idea of cause is based simply is
on the formation of a habit or expectation, based on
past experience.
– Additionally, we can’t prove that X will always cause
Y, or more generally that the future will be like the
past. It’s simply a matter of custom of habit.

The Problem of InductionThe Problem of Induction
• Hume’s reasoning implies the Problem of
Induction: what justification is there for inferring
that what was true of a sample in the past, will
be true of a whole population in the future?
– Arguing that since inductive generalization has been
successful in the past it will be successful in the
future, is itself an inductive generalization and so
assumes that inductive generalization is justified
which is what must be proved.
– What solutions to the problem of induction does the
text bring up, and how are they flawed?
• CHAPTER FIVE: THE SOURCES OF KNOWLEDGECHAPTER FIVE: THE SOURCES OF KNOWLEDGE

The Problem ofThe Problem of
the External Worldthe External World
• Hume’s philosophy brings up an even more
disturbing possibility: that there is no external
world.
– Of course we assume there is an external, regular,
and predictable world outside us.
– But how can we know for sure that there is a world
beyond our sense impressions when all we know are
our own impressions?
– How does Hume’s position differ from Berkeley’s?

In Hume’s Own WordsIn Hume’s Own Words
• “It is a question of fact, whether the perceptions of the
senses be produced by external objects, resembling
them: how shall this question be determined? By
experience surely; as all other questions of a like nature.
But here experience is, and must be entirely silent. The
mind has never anything present to it but the
perceptions, and cannot possibly reach any experience
of their connection with objects. The supposition of such
a connection is, therefore, without any foundation in
reasoning. . .” (350)

The Roots of SkepticismThe Roots of Skepticism
• Notice how skepticism is almost prefigured in
the starting assumption of Descartes and Locke
– that it’s possible that the ideas in our minds
may not correspond to a reality outside the
mind.
– This seems to leave us with a lack of certainty about
those things most of us are most certain.
– Is there any way to rescue belief in an external world,
and hold onto Descartes’ and Locke’s assumptions?

Prisoners of our MInds?Prisoners of our MInds?
• Some philosophers, such as Barry Stroud, appear to
endorse skepticism:
– “We are in a sense imprisoned within those
representations, at least with respect to our
knowledge. Any attempt to go beyond them to try and
tell whether the world really is as they represent it to
be can yield only more representations, more
deliverances of sense experience which…are
compatible with reality’s being very different from the
way we take it to be on the basis of our sensory
experiences.” (352)
• The desire to avoid skepticism is what animates the
philosopher Immanuel Kant (1724–1804) .

5.4 Kant: Does the Knowing Mind
Shape the World?
• With Hume’s skepticism, Kant believed that
philosophy had reached a crisis.
– Rationalists had claimed that the mind, by itself, is a
source of knowledge.
– Empiricists replied that the senses are the only valid
sources of knowledge.
– Hume went on to argue that the senses provide no
evidence for the causal laws of science.
– Kant sought to bring together both rationalism and
empiricism, and overcome Hume’s skepticism, while
establishing the objective basis of science.

Transcendental IdealismTranscendental Idealism
• Kant’s new viewpoint, dubbed transcendental
idealism, holds that the world we perceive and
know through science is a construct of the mind,
but one that depends on the senses.
– The senses are the source of the sensations, such as
colors and sounds, but what we perceive and know
isn’t built bottom-up from these.
– Rather, the mind organizes our sensations according
to its own rational rules or laws.
– So, the mind can know the laws that govern
everything we perceive.

Hume’s ChallengeHume’s Challenge
• Recall that Hume challenged objective scientific
knowledge, when he argued that the universal
laws of science, particularly cause-and-effect
laws, go beyond the evidence of our senses.
• Kant took this challenge seriously:
– “I openly confess that my recollection of David Hume
was the very thing which many years ago first awoke
me from my dogmatic slumber and gave my
investigations in the field of speculative philosophy a
quite new direction. But I was far from following him in
the conclusions at which he arrived.”” (354-355)

Areas of AgreementAreas of Agreement
• Kant agreed with Hume that both mathematics
and natural science go beyond the evidence of
the senses when they articulate universal laws
– Mathematics contains universal laws such as “The
shortest distance between any two points is always a
straight line,” and “2 X 3 = 6.”
– Natural science contains universal statements such
as “Every event must have a cause,” and “Every
action causes an equal and opposite reaction.”
• Nevertheless, Kant argued we have real
knowledge in these fields.

Synthetic A Priori StatementsSynthetic A Priori Statements
• Kant’s viewpoint hinges on his claim the universal
laws, such as “Every event has a cause” are
synthetic a prioris.
– These tell us something about the world, but are
justified through reason alone.
– A priori statements are true just based on reason.
• They are to be contrasted with a posteriori statements which
depend on the evidence of the senses.
– Synthetic statements tell us something about the world
around us.
• They are to be contrasted with analytic statements which are
tautologies or true by definition.

AppearancesAppearances
• The mind is already at work in constructing the
appearances we perceive.
– While Hume is right that all knowledge of the world
begins with the sensations that stream past our
senses: colors, shapes, etc.
– Kant points out that we do not experience a mere
display of sensations streaming through us.
• When you look around the room you do not merely see
numerous patches of color streaming past your vision.
Instead, you see objects, such as your desk, some books
and a sheet of paper.
• How is this possible?

The Mind as OrganizerThe Mind as Organizer
• Kant argues that what makes objective
appearances possible is the activity of the mind
itself, as it structures our constantly changing
sensations by organizing them into objects that
we experience as located in space and time.
– He argued that we cannot get our ideas of space and
time from experience because experience
presupposes space and time.

SpaceSpace
• Our experience presupposes space:
– “Space is not a . . . concept [we] derived from
outer experiences. For in order that certain
sensations be referred to something outside
me (that is, to something in another region of
space from that in which I find myself), . . . the
representation of space [already] must be
presupposed.” (357)

TimeTime
• Time is another mental structure that the mind
uses to organize the many sensations it
receives.
• Like space, it is thus presupposed by
experience:
– “Time is not a . . . concept . . . derived from any
experience” because before we can experience things
happening “before” or “after” or “simultaneous with”
other things, “the representation of time [must be]
presupposed.” (357)

MathematicsMathematics
• Kant argues that the laws of mathematics arise
from reasoning about the structures of space
and time that we carry around within our own
minds.
– Geometry gives us the laws of space.
– Arithmetic gives us the laws of time.
– We can establish the laws of geometry and arithmetic
entirely within our minds, because the structures of
space and time are already in the mind.

Natural ScienceNatural Science
• Kant also has to prove that we also have good
reason to believe that the synthetic a priori
causal laws of science that the mind establishes
must hold everywhere in the universe we see.
– He proves this again by arguing that when the mind
organizes its sensations into objects that change, the
mind puts these changes—that is, these events—into
causal relationships with each other.
– So, we can be certain that every event (change in an
object) that we perceive is caused by some prior
event (change in an object).

How Objects are ConstructedHow Objects are Constructed
• Kant develops a philosophical psychology of
how objects are constructed by the mind:
– First, the mind has to “run through” or receive the
many different sensations as they stream by.
– Then it has to remember each sensation after it
vanishes and is replaced by a new sensation.
– Finally, it has to be conscious that the earlier
sensations and the later ones are all sensations of the
same object.

The TranscendentalThe Transcendental
Unity of ApperceptionUnity of Apperception
• The mind can do all this only if it itself also
endures through time.
– The process of producing an object that remains the
same object as it changes over time requires that my
mind also remains the same mind during that
process.
– This implies that the mind is a single unified
awareness that remains the same unified awareness
as time passes.
– Kant uses a special term for this unified awareness:
the “transcendental unity of apperception.”

Cause and EffectCause and Effect
• The unified mind makes connections between
the changing objects it puts together from its
sensations through is imposition of a grid of 12
categories, one of which is cause-and-effect.
– Kant argues that the objects we perceive outside
appear to change, and not usually through own
agency, but independent of what we do.
– He claims that the mind has to impose cause-and-
effect relationships on the changes that we perceive if
they are to appear to be changes that occur
independently of ourselves.

In SumIn Sum
• Kant is arguing that:
1. That the mind is a unified awareness.
2. If the mind is to be aware of its many sensations, it must
connect these sensations together into a single unified world of
connected objects.
3. One of the ways the mind connects its sensations into a single
unified world of interrelated objects is by making all changes
causally related to other changes in that world.
4. These causal relationships are connections the mind must
make so that it can bring a unified and independent world into
its awareness.
5. The world we are aware of, then, has to be a unified world in
which all independent events or changes must have a cause.

Copernican RevolutionCopernican Revolution
• Kant responded to Hume’s skepticism with a
revolutionary answer:
– We know our ideas can represent the world
accurately because the mind itself constructs the
world.
– Kant claimed that his revolutionary claim that the
world must conform to the mind was a kind of
“Copernican” revolution in knowledge.
• Kant had replaced the view that the mind must conform to
the world, with the view that the world must conform to the
mind.
CHAPTER FIVE: THE SOURCES OF KN,OWLEDGECHAPTER FIVE: THE SOURCES OF KN,OWLEDGE

RomanticismRomanticism
• Numerous thinkers have accepted Kant’s insight
that the world is a construct of the mind.
– The Romantics were early 19th
century thinkers,
poets, artists, and philosophers who were fascinated
by the strange and exotic, particularly in cultures and
in nature.
– They agreed with Kant that we shape and create the
world we see around us, but thought that the shapers
were history, language and culture, and not Kant’s
universal categories.

Von HomboltVon Hombolt
• The Romantic philosopher Wilhelm von
Humboldt (1767-1835) argued that the language
of each culture contains the basic categories
and structures that the people of that culture use
to understand and organize their experience.
– We construct the world that we see according to the
categories of the language that our culture happens to
use.
– The world that we see around us, then, mirrors the
language that our culture and our history happen to
give us.

The Sapir-Whorf HypothesisThe Sapir-Whorf Hypothesis
• Hombolt’s insight has been developed by
numerous psychologists and social scientists
who are sometimes labeled Constructivists.
– One influential anthropological theory, was developed
by the American anthropologists Edward Sapir and
Benjamin Lee Whorf.
– The Sapir-Whorf hypothesis says that the structure of
a language determines how a speaker of that
language thinks.
• For example, Whorf argues that the language of the Hopi
makes them see and feel time as a cyclic recurrence.

Closing QuestionsClosing Questions
• Kant developed his theory as answer to Hume’s
skepticism, but does it really overcome it?
– For Kant, we never really reach contact with a world
independent of us, in any absolute sense.
• But doesn’t this imply another kind of skepticism?
– Additionally, Romanticism and social science makes
us wonder about Kant’s mental categories
themselves.
• Are they a complete list and description; are they the same
for everyone or, as some constructivists claim, different for
different people?

5.55.5 Does Science Give
Us Knowledge?
• We now turn to scientific knowledge, with the
focus of separating real scientific knowledge
from bogus or pseudoscientific knowledge.
– We will discuss several views of science, and as we
do so we will see that the three approaches to
knowledge we’ve surveyed each make important
contributions to our understanding of what scientific
knowledge is and how it differs from pseudoscience.
– One of the questions we’ll be focusing on differing
accounts of how scientific laws and theories are
related to sense observations.

Bacon’s InductionismBacon’s Inductionism
• Inductionism is an influential theory of how
scientific theories relate to sensory observations.
– The philosopher, Francis Bacon (1561–1626) claimed
that science is based on inductive reasoning, which
moves from many particular observations to claims
about the general laws that govern what we observe.
• Rather than relying on assumptions from past thinkers,
scientists should collect as many facts as possible, and use
experiments to generate additional facts.
• They should then carefully sift through the facts, looking for
common patterns, until they derive general laws about those
facts.

Mill’s InductionismMill’s Inductionism
• John Stuart Mill (1806–1873) argued that that
scientific method has three features:
– The accumulation of particular observations.
• Scientific method begins by collecting as many observed
facts as possible about the subject being investigated.
– Generalization from the particular observations.
• Scientific method then proceeds by inferring general laws
from the accumulated particular facts.
– Repeated confirmation.
• As more particular facts are accumulated, the more particular
instances of a “law” we find, the more confirmation the law
has and the higher its probability..
• l

Problems with InductionismProblems with Inductionism
• Although noteworthy scientists, including Galileo
and Mendel, made use of inductive reasoning,
still inductionism has a number of problems.
– For example, every generalization has to go beyond
the observations on which it is based, and many
generalizations will fit the same body of evidence..
– Additionally, almost none of the great scientific
theories are mere generalizations from a few facts.
• For example, Darwin never observed the evolution of any
species because the evolution of a single species would take
many lifetimes.

The Hypothetical MethodThe Hypothetical Method
• Because of problems with inductionism, many
philosophers turned away from it to reflection on
the necessity of the hypothetical method.
– William Whewell (1794–1866 ) argued that advances
in scientific knowledge do not depend only on
generalizations based on several observations.
– He contended that the greatest scientific advances
occur when scientists make a creative guess or
hypothesis about what causes or explains a particular
phenomenon and then test this hypothesis by sense
observations and experimentation.

Relying on ReasonRelying on Reason
• In formulating a hypothesis, the scientist turns
away from the senses, and relies on reason to
help her create new relationships and structures,
and to organize these into a theory that orders,
systematizes, and explains whatever
observations other scientists have made.
– Then, the scientist returns to sensory observations by
asking whether the theory accurately predicts new
observations, whether it suggests fresh research and
new experiments, or whether it points the way toward
other corroborating observations.

Popper and FalsifiabilityPopper and Falsifiability
• Karl Popper (1902-1994) was the most
influential proponent of the hypothetical method
in the twentieth century.
– Popper agreed that scientific theories are not mere
generalizations from experience, and makes use of
hypotheses that can explain many different
phenomena and that guide later research.
– But what really distinguishes the claims of science
from unscientific claims, Popper claimed, is that
scientific claims or hypotheses must be capable of
being falsified through empirical observations.

FalsifiabilityFalsifiability
• Any theory, Popper pointed out, can be shown to
be consistent with some observed facts: science
does not proceed by trying to find facts that
confirm a theory.
– Instead, the mark of science is that it tries to disprove
or falsify proposed theories.
– A real scientific theory is not just one that is confirmed
by some observations that suggest it is true, but one
that survives repeated attempts to prove it is false.
– One implication of falsificationism is that scientific
knowledge is never more than probable.

Paradigms andParadigms and
Revolutions in ScienceRevolutions in Science
• Popper’s falsificationism may not accurately
describe science because it ignores the extent to
which scientists are human beings.
– As humans they work together, they are trained in
universities to accept certain laboratory and research
methods, and they are deeply convinced that the
basic theories of their subject are correct.
– As a result, scientists tend to continue accepting a
basic theory even if they run into observations that
falsify the theory.

IndoctrinationIndoctrination
• The American philosopher and historian of
science Thomas Kuhn (1922–1996) argued that
we should think of scientific knowledge as the
product of communities of scientists who accept
and work with that knowledge.
– A person who decides to become a scientist receives
a long “indoctrination” into the theories and research
methods of their scientific community.
• This research tradition or paradigm of science includes a way
of thinking and doing research; the student-scientist is taught
the basic theories of the field and the correct methods for
applying and extending those basic theories.

RevolutionRevolution
• Kuhn argued that science does not grow
gradually, as inductionists and falsificationists
claim.
– Most of the time, scientists hold onto their theories
even if a few observations, called anomalies, show
up, that do not fit their theory.
– When too many anomalies that do not square with a
theory accumulate a “crisis” results.
• A revolution in the community can occur when some
scientists, particularly younger ones, start to rethink the
theory., and develop new theories that take the anomalies
into account.

Examples ofExamples of
Scientific RevolutionsScientific Revolutions
• The change from the medieval theory that the sun
revolves around the earth to the revolutionary theory of
Copernicus that the earth revolves around the sun.
• The change from Newton’s theory that time and space
are absolute and unchanging to the revolutionary new
theory of Einstein that time and space are relative.
• The change from the theory that animal and plant
species do not change to Darwin’s revolutionary new
theory of evolution.

Five CriteriaFive Criteria
• On the one hand, Kuhn’s view seems to provide
us with no way of answering this question other
than to say that a theory is scientific if the
community of scientists accepts it.
• On the other hand, Kuhn provided five criteria for
what makes scientific theory good.
– Accuracy, Consistency with other accepted theories,
Broadness, Simplicity, Fruitfulness.
– These criteria place Kuhn squarely in the rationalist
tradition.

Science versus PseudoscienceScience versus Pseudoscience
• Scientific method differs from pseudoscience in
its:
– Being based on sense observation and rationality;
– Reliance on the inductive method for its low-level
laws;
– Proceeding by formulating hypotheses that can guide
research;
– Being falsifiable, at least in principle;
– Being widely accepted in the community of scientists;
– Embodying theories that are accurate, consistent with
other accepted theories, broad, simple, and fruitful.

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