Philosophy as Adventures of Ideas

Week28

Philosophical Problems

on Knowledge: An Overview

Kazuyoshi KAMIYAMA

2016/12/16

CONTENTS

knowledge-based society(Peter Drucker)

What is knowledge?

K=JTB (the standard analysis of propositional knowledge)

Is knowledge a belief?

Knowledge implies truth? What is truth?

Are our beliefs justified?

Is the standard analysis of knowledge proper?

Do we on earth “know” something?

Contextualism

Invariantism vs contextualism, which is correct?

A variety of knowledges

References

THE NEXT SOCIETY WILL BE A KNOWLEDGE-BASED SOCIETY

Drucker, P.F. (1969). The age of discontinuity: Guidelines to our

changing society. New York, NY: Harper & Row

WHAT IS KNOWLEDGE?

PROPOSITIONAL KNOWLEDGE

I know that he is Donald Trump.

He knows that the earth is the third planet of the solar system.

know-what (facts) or propositional knowledge

cf. know-how (or procedural knowledge): I know

how to ride a bicycle.

In this session we will deal with just propositional knowledge.

What is it that a person knows a matter?

THE STANDARD(OR TRADITIONAL)ANALYSIS OF

PROPOSITIONAL KNOWLEDGE

p: a proposition

A subject S knows that p if and only if

(1) S believes that p,

(2) p is true, and

(3) S is justified in believing that p.

K=JTB (Knowledge is the justified true belief)

K=JTB

KNOWLEDGE

=

JUSTIFIED TRUE BELIEF

1ST PROBLEM ON STANDARD ANALYSIS

IS KNOWLEDGE A BELIEF?

Belief Knowledge

“I know that it is raining, but I do not believe it.”

Is this sentence absurd?

If your answer is “Yes,” you believe that knowledge

implies belief.

NOTE 'MOOREAN' SENTENCES

Moore's paradox

Moore's paradox concerns the apparent absurdity involved in

asserting a first-person present-tense sentence such as, "It's raining,

but I don't believe that it is raining" or "It's raining but I believe that

it is not raining." The first author to note this apparent absurdity was

G. E. Moore. These 'Moorean' sentences, as they have become

known, are paradoxical in that while they appear absurd, they

nevertheless:

1.Can be true,

2.Are (logically) consistent, and moreover

3.Are not (obviously) contradictions.

There is currently no generally accepted explanation of Moore's

paradox in the philosophical literature. (Wikipedia)

2ND PROBLEM ON STANDARD ANALYSIS

KNOWLEDGE IMPLIES TRUTH?WHAT IS TRUTH?

Truth Knowledge

To say of what is, that it is not– or of what is not,

that it is– is false. While to say of what is, that it is–

and of what is not, that it is not– is true.

（Aristotle, Metaphysics）

THE LIAR PARADOX(OR EPIMENIDES PARADOX)

A Cretan states that “all Cretans are liars.“

* Epimenides (Cretan philosopher, alive circa 600 BC)

A PARADOX OF SELF-REFERENCE

“This sentence is not true.” (1)

if (1) is true, then (1) says, truly, that (1) is not true so

that (1) is not true; on the other hand, if (1) is not true,

then what (1) says is the case, i.e., (1) is true.

Note: “this sentence" refers to (1) (the sentence itself).

RUSSELL'S PARADOX(1901)

Naive set theory(G.Cantor1845-1918)：For any

property there exists the set which consists of all

things that satisfies the property

A property：being not members of themselves

ex. The set of all Americans

R＝ the set of all sets that are not members of

themselves

R= [x: ¬(x∈x)]

If R∈R, then ¬(R∈R). Contradiction.

If ¬(R∈R), then R∈R. Contradiction.

Contradiction.

DOUBTS ON THE PREDICATE “TRUE”

Given such a paradox, one might be skeptical of the

notion of truth, or at least of the prospects of giving a

scientifically respectable account of truth.

THE DEFINITION OF TRUTH BY TARSKI

Alfred Tarski, 1935, “Der Wahrheitsbegriff in den formalisierten

Sprachen”, Studia Philosophica, 1: 261–405. （“The concept of truth

in formalized languages”）

Convention T:

An adequate theory of truth for L must imply, for each sentence φ of

L ⌈ φ ⌉ is true if and only if φ .

For detail, see Logic textbook.

PROBLEMS OF TARSKI’S THEORY OF TRUTH (FOR PHILOSOPHERS)

(1) It is the definition of truth for formalized languages

(not for ordinary languages).

(2) It doesn't actually tell us why/when/how a sentence

is true.

OVERVIEW OF TRUTH THEORIES

Ⅰ Positive views: Truth exists.

Ⅰ-1. Inflationism： To define “true” with thick ontology

Ⅰ-2. Deflationism： To define “true” with thin ontology, or

without ontology

Ⅱ Negative views： Truth doe not exist. Knowing truth is not

possible. : Agnosticism, Nihilism

Ⅰ-1(INFLATIONISM) A. CORRESPONDENCE THEORY

A belief is true if there exists an appropriate

entity—a fact—to which it corresponds.

If there is no such entity, the belief is false.

Ⅰ-1(IFNLATIONISM) B. COHERENCE THEORY

A proposition is true if it coheres (or agrees) with

other propositions we already hold to be true.

Ⅰ-1(INFLATIONIAM) C. PRAGMATIST THEORIES

C.S. Pierce (1839–1914)

William James(1842–1910)

A proposition is true if it is useful to believe it.

Those propositions that best justify what we do and

help us to achieve what we are aiming at are true.

Ⅰ-2(DEFLATIONISM) C. DISQUOTATIONALISM

W.Quine(1970)

An attribution of truth to a sentence undoes the effects

of the quotation marks that have been used to form

sentences: Sentence "S" is true if and only if S.

For detail on the theories of truth, see

http://www.slideshare.net/kazu2015/paai7-what-is-truth-

58405748

3RD PROBLEM ON STANDARD ANALYSIS

IN THE FIRST PLACE, OUR BELIEFS ARE JUSTIFIED?

Any belief is not assertable because it is jot justified.

Why not justified?

We have the following argument which shows that any

belief is not justified.

AGRIPPA’S TRILEMMA

For any person S and any proposition p that S believes, any line

of argument purporting to show that S is justified in believing

that p will:

a) lead to regress from belief to belief without ever stopping.

(infinite regress)

or

b) terminate in an undefended assumption. (ad hoc assumption)

or

c) form a circle. (vicious circle)

In any case, S’s belief that p is not justified.

Therefore, for any person S and any proposition p that S believes,

S’s belief is not justified.

If knowledge requires justification, it follows that

nobody knows anything.

＊Agrippa the Skeptic：Skeptic philosopher at the end

of the 1st century

NOTE: TRILEMMA

Dilemma

A or B

If A, then X.

If B, then X.

➩ X

Trilemma

A or B or C

If A, then X.

If B, then X.

If C, then X.

➩ X

Both are valid scheme of inference.

For detail on the ancient skepticism, see

http://www.slideshare.net/kazu2015/paai4-the-challenge-by-

skeptics

4TH PROBLEM ON STANDARD ANALYSIS

IS THE STANDARD ANALYSIS OF KNOWLEDGE PROPER?

GETTIER’S COUNTEREXAMPLES

Edmund Gettier,

"Is Justified True Belief Knowledge?“

Analysis, 23, 1963, 121-3.

THE THESIS OF GETTIER

(1)∧(2)∧(3) is not the sufficient condition for “S knows that p.”

JTB

K

PROOF

Let us show that there are (intuitively) false knowledge

sentences that satisfy all three requirements( (1)，(2) and(3)).

In other words, there are cases of justified true belief that one

would be hesitant to call knowledge.

TWO REQUIREMENTS ON JUSTIFICATION

H1 It is possible for a person to be justified in believing a

proposition that is in fact false.

H2 For any proposition p, if S is justified in believing p, and p entails q, a

nd S deduces q from p and accepts q as a result of this deduction, then S

is justified in believing q.

(Justification is preserved by entailment.)

CASE1:SMITH'S JOB（ONE OF GETTIER’S TWO COUNTEREXAMPLES）

Suppose that Smith and Jones have applied for a certain job. And suppose that Smith has strong evidence for the following conjunctive proposition:

(a) Jones is the man who will get the job, and Jones has ten coins in his pocket.

Smith’s evidence for (a) might be that the president of the company assured him that Jones would in the end be selected, and that he, Smith, had counted the coins in Jones's pocket ten minutes ago.

Proposition (a) entails:

(b) The man who will get the job has ten coins in his pocket.

Let us suppose that Smith sees the entailment from (a) to (b), and

accepts (b) on the grounds of (a), for which he has strong evidence. In

this case, by H2，Smith is justified in believing that (b) is true.

But imagine, further, that unknown to Smith, he himself, not Jones, will

get the job. And, also, unknown to Smith, he himself has ten coins in

his pocket. Proposition (b) is then true, though proposition (a), from

which Smith inferred (b), is false.

All of the following are true:

(1) Smith believes that (b).

(2) (b) is true.

(3) Smith is justified in believing that (b).

Smith has the justified true belief on (b). Therefore, according to the

standard analysis, he knows that (b) is true. But, it is clear that Smith

does not know that (b) is true; for (b) is true in virtue of the number of

coins in Smith's pocket, while Smith does not know how many coins

are in Smith's pocket, and bases his belief in (b) on a count of the

coins in Jones's pocket, whom he falsely believes to be the man who

will get the job.

THE GETTIER PROBLEM

Are the Gettier’s examples true counterexamples to the standard

analysis?

(If they are) How should we amend the standard analysis to reach the

proper analysis of knowledge?

THE REVISIONS OF THE STANDARD ANALYSIS: TWO TYPES

Internalism Refinements of justification condition

K=JTB+X（the 4th condition）or K=JTB(refinement of the justification condition)

causal theories, reliabilism, relevant alternative theories, defeasibility analysis,・・

Externalism Giving up justification condition

K=TB+WKnowledge does not require justification.It requires just “warrant” which connects belief to fact.

truth-tracking theory, safety theory,・・

INTERNALISTIC ANALYSIS(AN EXAMPLE)

Causal theory(A.Goldman,1967)

causal condition

A subject's belief is justified, only if the truth of a belief has

caused the subject to have that belief (in the appropriate way);

and for a justified true belief to count as knowledge, the subject

must also be able to "correctly reconstruct" (mentally) that

causal chain.

Goldman's analysis would rule out Gettier cases in that

Smith's beliefs are not caused by the truths of those

beliefs; it is merely accidental that Smith's beliefs in the

Gettier cases happen to be true.

A COUNTEREXAMPLE OF CAUSAL THEORY:DEATH OF OMAR

(1) Omar dies because of heart attack.

(2) Later his head is cut off.

(3) Then Smith sees the decapitated Omar.

(4) Smith believes (a) Omar is dead and (b) Omar died because he

was decapitated.

According to the standard theory, Smith knows (a) because of his

perception of a decapitated Omar, but the causal theory says Smith

does not know (a) because his belief is not caused by the true cause

of Omar’s death(heart attack).

Obviously Smith knows (a).

EXTERNALISTIC ANALYSIS (AN EXAMPLE)

Nozick（1981)：K=TB+(1),(2)

where

(1) If p were false, S would not believe that p. (sensitivity to falsity)

(2) If p were still true in somewhat different circumstances, S would still believe it and would not believe that not-p. (sensitivity to truth)

*A belief that fulfills these conditions is one that, in Nozick's expression, "tracks the truth."

Knowledge is the truth-tracking True Belief.

A COUNTEREXAMPLE:THE RED BARN CASE

Peg is looking at a red barn. As it turns out, she is in an environment where red barns cannot be faked though barns of other colors can be faked. Peg has perfect eyesight and is observing the barn under standard lighted viewing conditions. According to Nozick’s conditions(truth, belief, and the two tracking conditions: if p were not true, S would not believe that p, and if p were true, S would believe that p), Peg knows there is a red barn.

Peg does not know there is a barn because she fails’ Nozick’s tracking condition that if there were not a barn, Peg would not believe there were. She fails this condition because she would believe of a white fake barn, for instance, that it is a barn.

Peg knows there is a red barn. But she does not know one of its obvious logical consequence; there is a barn.

Kripke(2011)

For more detail on the Gettier problem, see

http://www.slideshare.net/kazu2015/paai26-2016913.

A PROBLEM ON KNOWLEDGE

DO WE ON EARTH “KNOW” SOMETHING?

SKEPTICAL ARGUMENTWHICH LEADS TO THE GLOBAL OR

CARTESIAN SKEPTICISM

Brain in a vat(BIV)

You are told to imagine the possibility that at this very moment

you are actually a brain hooked up to a sophisticated computer

program that can perfectly simulate experiences of the outside

world. Here is the skeptical argument. If you cannot now be sure

that you are not a brain in a vat, then you cannot rule out the

possibility that all of your beliefs about the external world are

false. Or, to put it in terms of knowledge claims, we can construct

the following skeptical argument.

(1) I do not know that I am not a BIV.

(2) If I do not know that I am not a BIV, I do not know

that I have hands.

Therefore,

(3) I do not know that I have hands.

(Argument from ignorance)

* How do you deal with this argument?

CONTEXTUALISM

Contextualism(attributer contextualism) is the view that the truth-

conditions of knowledge ascriptions, such as ‘S knows that P’, are

context-sensitive.

In particular, knowledge ascriptions are context-sensitive in virtue

of ‘knows’ being context-sensitive.

The attributer’s context determines how strong an epistemic

position S must be with respect to P in order for ‘S knows that P’ .

Thus an attributer in one context could truly say ‘S knows that P’,

while simultaneously an attributer in a different context could

refer to the same person at the same time with respect to the

same proposition, and truly say ‘S does not know that P’.

Invariantism denies that the truth-conditions of knowledge

ascriptions are context-sensitive. They remain constant,

invariantists say, across contexts. (Turri,2010)

IN OTHER WORDS

When a person A states that "S knows that P," he ascribes knowledge

of P to S.

"S knows that P" is true iff S is in a strong epistemic position EP with

respect to P, where the EP is determined by the attributer A's context

of utterance.

So the knowledge ascriptions (or "knows") are context-sensitive,

where the context is that of the attributer.

This is the “attributer contextualism”. Although there are other

versions of contextualism, the attributer contextualism (S.Cohen,

K.DeRose) is the standard one.

THE BANK CASE（K.DEROSE,1992）

A. Hannah and Bob are driving home on Friday. They had

planned to stop at the bank, but notice long lines. Asked whether

she knows if the bank will be open tomorrow, Hannah recalls

going to the bank on Saturday, and says ‘‘Yes, let’s go then

instead.’’

B. Bob reminds her that the funds must be in the bank by

Monday morning, otherwise some checks will bounce. Noting

that banks sometimes change their hours, he asks whether she

really knows that it will be open. Hannah pauses, and says ‘‘No.

We’d better go now.’’

Contextualists

At case A； (*) I know that the bank will be open tomorrow.

At case B； (**) I do not know that the bank will be open tomorrow.

(*) and (**) appear to contradict each other. They do not necessarily

contradict. Both could be true. The contexts are different.

Invariantists

At first(at case A), Hannah thought that she knows the bank will

open tomorrow. After Bob’s reminder (at case B), Hannah

withdrew her knowledge claim. She conceded that she does not

know the bank will open tomorrow.

CONTEXTUALIST SOLUTION TO THE BIV SKEPTICISM

In (1) of the skeptical argument, BIV puts an attributer in the

context which requires him to use a high standard of justification.

(3) is a conclusion in the context. This argument and its

conclusion is correct. But it does not imply anything in the

ordinary context in which low standards of justification are used.

* Do you accept this argument?

A PROBLEM ON KNOWLEDGE

INVARIANTISM VS CONTEXTUALISM: WHICH IS

CORRECT?

Does the meaning of “know” in the utterance of “S knows that p”

vary in the contexts or not?

EXPERIMENTAL PHILOSOPHY

How do ordinary people judge on this problem?

Let’s ask them!

Experimental philosophy is an emerging field of philosophical

inquiry that makes use of empirical data—often gathered

through surveys which probe the intuitions of ordinary people—

in order to inform research on philosophical questions.

This use of empirical data is widely seen as opposed to

a philosophical methodology that relies mainly on a

priori justification, sometimes called "armchair" philosophy, by

experimental philosophers.

The philosophical movement Experimental Philosophy began

around 2000.(Wikipedia)

A VARIETY OF KNOWLEDGES：A GLANCE AT FURTHER TOPICS OF MODERN

EPISTEMOLOGY

perceptual knowledge ： Cognitive psychology, Artificial Intelligence

稲見昌彦『スーパーヒューマン誕生! ―人間はSFを超える』NHK出版新書、2016年

individual knowledge： Philosophy, Logic（epistemic logic)

common knowledge： Game theory

collective intelligence： Information theory

西垣 通『集合知とは何か―ネット時代の「知」のゆくえ』 中公新書、2013年

organic intelligence:環境を観測するセンサーや各種コンテンツ配信システムがインターネットへ接続さ

れ、地球全体で情報が統合処理される結果として成立する地球規模の知性

local knowledge： Cultural anthropology

C.Geertz, The Interpretation of Cultures: Selected Essays, 1973.

tacit knowledge： Business administration

I. Nonaka and H.Takeuchi, The Knowledge-Creating Company: How Japanese

Companies Create the Dynamics of Innovation, 1995.

REFERENCES

““Brain in a Vat” Argument, “ The Internet Encyclopedia of Philosophy,

www.iep.utm.edu/brainvat/

DeRose, K. (1992):” Contextualism and Knowledge Attributions,”

Philosophy and Phenomenological Research 52, 913–929.

Goldman, A. I.(1967): ”A Causal Theory of Knowing,” The Journal of

Philosophy 64, 357–372.

Kripke, S.A. (2011): “Nozick on Knowledge,” in Philosophical Troubles:

Collected Papers, Volume 1, Oxford: Oxford University Press.

Nozick, R. (1981): Philosophical Explanations, Harvard University Press.

Turri, J.(2010): “Epistemic Invariantism and Speech Act Contextualism ,”

org/research/EI+SAC.pdf.