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CHAPTER FIVE: THE SOURCES OF CHAPTER FIVE: THE SOURCES OF KNOWLEDGEKNOWLEDGE

P H I L O S O P H YP H I L O S O P H YA TEXT WITH READINGSA TEXT WITH READINGS

1212thth EDITION EDITIONManual 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 the Innate 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 All 5.3 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 Secondary Primary 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 Subjective Berkeley’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 Exist Primary 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?

•


The Problem of The Problem of the External World the 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 Transcendental The Transcendental Unity of Apperception Unity 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?


5.5 5.5 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..

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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 and Paradigms 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 of Examples of Scientific Revolutions Scientific 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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