ADVANCED EPISTEMOLOGY
14/10/10
·
Course
Outline
1.
Epistemology
and sceptical challenge
2.
The
traditional definition of epistemology by Plato and the challenge of Edmund
Gettier
3.
Fundationalist’s
theories
·
The
rationalist project of Descartes
·
Hume’s
critique of induction (Causality)
·
Kant’s
mediation between the rationalist and empiricists
·
The
critique of Pure Reason
·
The
critique of a priori
·
Is
pure reason possible?
4.
Contemporary
theories of knowledge
·
Quinn’s
naturalised epistemology
·
Alvin
Goldman’s epistemic
5.
Theories
of truths
6.
Existentialism
and traditional epistemological theories
7.
Knowledge
and human interest
·
Class interaction:
·
Do
we really know something? Yes, we do
know something but there may be mistakes in what we know.
·
If
it is true that we do know something, why then would the sceptics argued we
cannot know anything?
·
Who
is a sceptic? A sceptic is one who doubts that human knowledge is possible.
·
Protagoras – For Protagoras all custom were
relative, not absolute. For him, everything is relative to human subjectivity. According
to him, man is the measure of all things, of things that are, that they are,
and of things that are not, that they are not.
·
Gorgias – According to Gorgias:
1.
There is nothing
2.
If
there were anything, no one could know it
3.
If
anyone did know it, no one could
communicate it
The point is that if you can ‘prove’ these
absurdities, you can ‘prove’ anything.
·
Descartes – Descartes began by doubting
everything in his treatment of epistemology
·
Sources of knowledge:
·
Sense
experience
·
Intuition
·
Reason
·
Revelation
F
Epistemology and sceptical
challenge
Introduction
Like philosophy itself, the definition of
epistemology, that is, theory of knowledge, can only be clearly formulated
after we have described what epistemology sets out to achieve. Epistemology
claims to tell us how knowledge is possible, the sources of knowledge, the
nature of knowledge and the scope of our knowledge. It grapples with such
issues as to the limits of our knowledge, what we know and how we know that we
know. One may therefore define epistemology as the branch of philosophy which
studies knowledge. More precisely, it refers to the objective and scientific
knowledge (episteme) as opposed to opinions.
Epistemology concerns itself with propositional
knowledge, that is, what it is for S to say that it knows P and so P. For one
to claim that one knows that P, it means that the art of knowing involves a
subject, that is, a knower and an object (the thing known).
Object
(thing known)
Subject (something that knows)
The epistemological enterprise has been
greatly challenged by the sceptics. Some of these sceptics include:
·
Thales
·
Pyrrho
·
Montaigne
·
Descartes
There are two broad kinds of scepticism:
total scepticism and partial scepticism. A total sceptic will insist that
knowledge is not possible. But the position of total scepticism is not feasible
because it is self-contradictory[1]. Genuine or partial
scepticism has to do with further inquiry. It recognises the fact that no
knowledge claim, no matter how sure we are, is free or immune from error. It
questions the notion of absolute certitude or certainty.
Systematic scepticism started with Thales
and continued through Pyrroh, Sextus Empiricus, the Sophists, and then René Descartes
who is regarded as a partial sceptic. The sophist Protagoras, sensing the
uncertainty in things and lack of absolute criteria, concludes that man is the
measure of all things, of things that are, that they are, and of things that
are not, that they are not – man determines everything. It should be noted that
whenever philosophy is getting into dogmatism, a claim that its truths are
incorrigible, it needs scepticism to save it.
v 15/10/10
F
Assignment:
What
is the relevance of scepticism to the epistemological enterprise? – 3 to 5
pages.
F
A. J. Ayer
A.J. Ayer gives 4 steps of the sceptical
argument that:
1.
We
rely on the premises for our knowledge of the conclusion
2.
Relationship
between the conclusion and the premises are not inductive
3.
The
move from premise to conclusion is also not inductive
4.
Therefore,
we are not justified in claiming that we know the conclusion
According to Ayer,
if one is not content to make merely dogmatic claims to knowledge, the range of
propositions which one regards as capable of being known to be true will
coincide with those which we can show to have sufficient justification for
accepting. The practice has always been to start with propositions which one
can be certain of or virtually certain of their truth and then see what further
propositions there can be supposed to justify. This method/procedure Ayer tells
us has its origin in Descartes methodic doubt. The aim of the sceptics,
according to Ayer, which is positive, is to demonstrate the existence of an
unbridgeable gap between the conclusions which we desire to reach and the
premises which we set out.
v 21/10/10
The inductive inference can enable us to
predict the occurrence of future sense impression on the basis of those that we
already have. But it cannot lead us to a conclusion which we could conceivably
verify. But then the sceptics concludes that if our belief in the existence of
physical object cannot be justified either by a deductive or inductive
argument, it means that it does not have any rational ground. The sceptic’s
position is further backed-up by the following arguments:
1.
Argument from illusion:
This argument claims that the senses often
deceive us and sometimes we confuse dream and hallucinations with reality.
Therefore sense knowledge cannot be trusted.
2.
Although
we are naturally convinced of the truth of the first principles, there is no
guarantee that they apply to reality. They might be merely laws of the mind.
3.
Any
attempt at proving the value of reason, necessarily involves a vicious circle
since we must of necessity use the intellect in formulating such a proof while
the value of the intellect for knowing and proving is not yet established
4.
Nothing
can be absolutely proved according to the sceptics for every argument supposes
premises and this in turn must be established by means of some further argument
and so forth ad indefinitum.
5.
Subjective
certitude is not sufficient. Many subjective convictions including those of
philosophers have proved upon closer inspection, to be false.
v
The traditional definition of
epistemology by Plato and the challenge of Edmund Gettier
For Plato, knowledge is not the same with
true-belief because knowledge requires an ability to give the ground on which
our claims of knowledge rests while true-belief is a matter of opinion and
liable to error whereas knowledge is not liable to error. This means that for
Plato, we cannot have knowledge of sensible things since we cannot attribute
the quality of absolute necessity to them which is a necessary ground for all
knowledge claims.
In the Theaetetus, Plato presents the dialogue between Theaetetus
the young mathematician and Socrates. They progressively moved from having
knowledge as aesthesis, that is, perceptions of what is. We cannot be wrong in
what we perceived and that means that we can have knowledge through perception.
Socrates argues that things are always changing and as such, we can never be
sure that what we claim to perceive is exactly what we are perceiving since
sensible things do not enjoy stability.
Again, it is doubtful if
our perceptual organs are effective and reliable in reporting what is. The
whole problem of misperception, illusion, delusion, hallucination and
phantasmagoria are very strong arguments against our perceptual process. This
means that there is an extra dimension to the question of knowledge through
perception. In our perceptual process, there is a place for judgement.
Perceiving is one thing, and then making the right perceptual judgement is
another.
We find here that
knowledge is therefore not a wholly sensible process but involves mental
activity of judgement. This leads us from the point of true-belief to the need
for justification; hence the traditional conception of knowledge as Justified
True Belief (JTB). The need to provide justification is very important
in knowledge, otherwise anything becomes acceptable as genuine knowledge claim.
v 28/10/10
v
The Challenge of Edmund Gettier to
the Traditional Definition of Epistemology
Let us recall that
Plato had given us a tripartite account of knowledge in the Theaetetus which takes knowledge to be Justified True Belief (JTB) in
order words S is the subject of knowledge while P is the object of knowledge,
the three conditions stated above must obtain; that is:
1.
P must be true
2.
S must believe that P
3.
S must be justified in
believing that P
This conception or
definition of knowledge was challenged by Edmund L. Gettier in his article: “Is
True Belief Knowledge?” 1963. According to Gettier, the three criteria for
knowledge are necessary but they are definitely not complete or sufficient for
knowledge.
·
First reason is that sense of justified in
which S’s being justified in believing that P. It is possible for a person to
be justified in believing a proposition that is in fact false.
·
Secondly, for any proposition P, if S is
justified in believing Q, and P entails Q and S deuces Q from P and accepts Q
as a result of this deduction, then S is justified in believing Q. Take
schematically:
P É Q
Q É R
\P
É
R
Gettier presents two cases in which the conditions
stated above are true for some propositions though it is at the same time false
that the person in question knows that proposition.
v Case
1: Suppose that Smith and Jones have applied for a certain bob and suppose that
Smith has evidence for the following conjunctive propositions.
1.
Jones is the man who will get the job and
Jones has ten coins in his pocket.
2.
Smith had counted the coins in Jones’
pocket to be ten and the president of the company told Smith that Jones would
be selected.
3.
At the end of the day, Smith got the job unknowing
to him; he too had ten coins in his pocket.
In
the above example, the three criteria for knowledge had been met yet Smith did
not know who will get the job.
F
A Critique of Gettier.
Edmund Gettier’s position
had been criticised by some contemporary philosopher. According to McGolderick,
the apparent successes of Gettier counter examples rests upon a conceptual
confusion. He argues that the Gettier counter example seem to attack JTB by
sliding between the various meaning of the word ‘justified.’ The way in which
the slide occurs is quite complex and is made possible by the complexity of the
concept of justification. Whereas a claim of conception cannot be justified on
the basis of false evidence; a person can be justified for holding a false
belief on the bases of false evidence because when applied to persons, a
justification exonerates from real blame.
What is justifies because
in the circumstances and on the basis of evidence at hand, that is, how it
appeared or that is what a reasonable or moral man would assume. But a claim,
theory or proposition cannot in the same way be justified on the basis of false
evidence. The evidence either establishes the truth of the claim or it does not.
If it does not or if at some future time it turns out that it did not, then, we
deny the claim is or was justified. To do otherwise would be to commit us to
the absurdity that claims or propositions themselves can be exonerated from the
falsehoods which they proclaim, if it can be shown that they were based on
false evidence.
When we apply this
analysis of the term ‘justification’ to the Gettier counter example, we see
that Smith is justified in believing that P in nether of the two senses
elucidated above. He cannot be justified in the sense of being exonerated from
the rebuke of having held a false belief since his belief is in fact true. At the
same times, the proposition that P is not justified in the sense that the
evidence on which it is based cannot be justified or sustained. Gettier’s sense
of justified can best be described as a mixed mood which fails to correspond to
the normal usage of the word.
F
Research Question:
What in your opinion are
the adequate criteria for knowledge? You must take cognisance of JTB and
Gettier’ counter example – 2 to 3 pages, hand written.
v 4/11/10
F The
Foundationalist Theories.
What
do we mean by a foundation? And why is a foundation important?
In building,
foundation is that part of a building, usually below the ground, that transfers
and distributes the weight of the building onto the ground. Foundation
therefore is the root, the base, the anchor of anything. In everything we do,
there is always a foundation. It is the platform on which everything rests.
Foundation is
important because there can be no building without it. In any field of
endeavour, there can be no progress without a foundation. In the history of
philosophy, there has been the problem of skepticism and this problem gave rise
to the need for a sure foundation on which base our knowledge claims. What
then, are the things that must be present so that our knowledge claims becomes
secured?
F Descartes
In his
philosophical enterprise, Descartes began by doubting everything so as to
establish a secured foundation of knowledge. Through his methodic doubt, he
discovered that the only thing he cannot doubt is his personality as a thinking
being – cogito ego sum. For Descartes therefore, the I, is the starting point
of true knowledge. Now, when one thinks, he is excising his brain and there is
a close connection with thinking and reasoning. Consequently, Descartes sees
reason as the bases of true knowledge.
v Read about
Descartes. Identify the major problem with the foundationalist’s theory of
Descartes, Locke and Berkeley; and make a small note to be discussed in the
class.
v 12/11/10
What all empiricists have in common is
their rejection of innate ideas and their insistence that all knowledge derives
from sense experience/perception and is circumscribed by sense perception. They
all maintain that at birth, the human mind is in a blank state – tabular rasa.
Some of the notable empiricists are John Lock, George Berkeley, and David Hume
F John Locke
John Locke lived between 1632 –1704. He
studied at oxford and worked as a secretary to a diplomatic mission, and
subsequently as a medical adviser to Lord Ashley. His main work is his essay
concerning human understanding.
Lock rejected the
theory of innate idea and argues that if there were innate ideas, children and
even idiots would know them. Again he argued that if moral principles were
innate (as advocates of innate ideas say), all men would have the same moral
principle. On the contrary, different people and different cultures have
different moral principles and practices. According to Locke, this shows that
there are no innate ideas. The human mind is blank at birth; all knowledge
therefore comes from sense perception/experience.
According to John
Locke, what is innate in us is the power of the intellect. For him, the actual
knowledge is acquired through experience or external world. The intellect helps
us to acquire knowledge through experience and he made a distinction between
senses:
·
Internal
sense
·
External
sense
·
Sensation
– according to him, helps us to acquire knowledge from without.
·
Inner
reflection – this helps us to acquire knowledge from within. And sense
experience also provides us with sensible qualities such as colour. When these
senses are acquired by the mind, the mind processes them. The rationalists
would insist that man has innate ideas but the empiricists disagreed with this
submission.
F Primary and Secondary Qualities.
Locke distinguishes
between primary and secondary qualities. Primary qualities are qualities that
are inherent in objects while secondary substances do not. We cannot speak of
an object without these qualities. Secondary qualities according to him are
attributes of the mind.
Examples of
primary qualities are:
·
Solidity
·
Size
·
Extension
Examples of secondary qualities are:
·
Sound
·
Taste
·
Smell
·
Colour
Secondary qualities are not qualities of
the object. They can be said to be accidental to objects.
F Ideas
Ideas are the immediate
object of human knowledge. This implies that we have no direct about them. How
are ideas of things formed in our minds? According to Locke, when we perceive
things, they impress their images or copies in our minds. These things are the
representatives of things in our minds and these are our ideas of things.
F Simple and Complex Ideas.
Locke
distinguishes between simple and complex ideas. Simple ideas are fundamental
ideas while complex ideas are built from simple ideas. Abstract ideas are ideas
from which all particular traits have been removed.
F Substances
Substances are formed from simple ideas
processed by the mind but we cannot perceive them. Primary qualities are
objective while secondary qualities are not. For John Locke, it is the primary
qualities that constitute the foundation of knowledge.
F
George Berkeley
George Berkeley
was born around 1685 – 1753. He studied in Trinity College, Dublin Ireland. He
is the second British empiricists. His main works are: “Essay towards a New
Theory of “Human Knowledge”, and “Dialogue between Hylas and Philonous.”
Berkeley’s philosophy is referred to as ‘immaterialism.” He was critical of
Locke’s theory of knowledge. He disagreed with Locke that physical objects
exist independently of being perceived. Whatever we know to exist, we know only
through sense perception and it exists only in so far as it is being perceived.
Thus whatever we experience is an idea in the mind. Berkley erroneously equated
the act of sense perception with ideas. For him, sense perception is idea.
Since whatever is
perceptible with the senses is an idea in the mind, it follows therefore that
there are no material object as such, that is, matter does not exist.
Everything in the world is an idea in the mind of the perceiver and it exists
only in so far as it is perceived. This leads to solipsism[2]. According to Berkeley,
the world consists of two things, namely;
1.
Those
which actively perceive, sense, and experience – subjects of perception
2.
Those
which are actively perceived, sensed and experienced – objects of perception.
According to him,
the mind is that which makes knowledge possible – to be is to be perceived.
Physical objects – table, trees, chairs etc, are nothing other than collections
of sensible qualities. These sensible qualities are classified as ideas and as
such their existence depends on their being perceived by an active mind,
whether finite or divine mind.
Berkeley however,
agreed with Locke that the subject of our knowledge is ideas not material
things in themselves. But what ideas? They differ: Locke says that they are
separate from things but represent them in our minds. Berkeley on the other
hand says that they not separate from things. They are things. Ideas are things
and things are ideas in the mind.
Berkeley rejects
Locke’s theory of material substance. He agrees with Locke however that we do
not perceive substance, we only perceive qualities. According to Berkeley, for
anything to exist, it must be perceived by the mind. The essential thing here
is that the human mind is very important. However, the problem in this theory
is the problem of the mind. Where is the mind?
In the final
analysis, he argues that physical objects are nothing than collection of
sensible qualities as ideas and as such their existence depends on their being
perceived.
NB. Rationalists will talk about innate ideas while
empiricists will talk about sensible qualities.
v 18/11/10
F David Hume
David Hume has
been described as a thorough going empiricist. In fact, he is said to have
pursued empiricism to its logical but disastrous conclusion. This is mainly
because he denied causation. Immanuel Kant also asserted that it was Hume’s
devastating critique of causation that woke him from his dogmatic slumber. Hume
presented the theses that what we are aware of is divided into two; namely:
1.
Impressions
and
2.
Ideas.
He believed that
what makes the difference in the two consists in their degree of liveliness.
Impressions according to him are livelier than ideas. Hume agrees with
Berkeley’s theses that we perceive ideas in our mind but he disagrees with the
thesis that if we do not perceive these ideas, they are perceived by God.
According to him,
impressions are the content of the mind in perception while ideas make up
imagination. It is obvious that Hume agrees with Locke on relations of ideas
and he disagrees with the non-empirical doctrine in Berkeley. But like
Berkeley, Hume also denied the existence of anything behind impression and that
every simple idea is a copy of corresponding impression.
Hume’s theory of
knowledge is sceptical because according to him, there is no justification for
the claims made on the basis of the conclusion we arrive at based on inductive
evidence. Hume’s critique of causation is part of the attempt by him to show
that knowledge gained through the senses cannot be conclusively established. He
is of the opinion that the fact that we have been observing two things
happening together does not necessarily mean that those two events or things
will always occur together. For instance, if event A, say the striking of a
match against a match-box, has always been followed by event B, lightening, we
cannot conclude that this event will always happen in this way.
Hume says that it
is possible to have event A without being followed by event B. This is because
a change in the course of nature is not inconceivable. Hume likens causation to
constant conjunctions and not a logical necessity or necessary connection. He
is of the opinion that we have psychologically constituted our minds to see
things happen in one way rather than the other. With this analysis, Hume
rejects causation and induction[3]. It should be noted that
Hume still gives primacy to the knowledge acquired through sense experience but
his main claim is that this knowledge clams cannot be verified conclusively in
experience.
v 25/11/10
F Immanuel Kant
Immanuel Kant
(1724-1804), was a German idealist philosopher and he took it upon himself to
resolve the conflict between the rationalists and the empiricists on the
question of our claim to knowledge of the external world. Kant’s major
contribution consists in his synthesis of the positions of the empiricists and
the rationalists. He did this by synthesising reason and experience. Kant’s
position was largely influenced by his critique of metaphysics. He was of the
opinion that what had passed as metaphysics earlier on were claims that were
irreconcilable, untenable and unsustainable because these claims went beyond
sense experience. Hence such metaphysical claims are apt to lead to skepticism.
Kant sought to
show that if metaphysics, which serves as the basis science is given up then
science will be in jeopardy. He therefore taught what is called Copernican
Revolution in philosophy to put metaphysics on the secure path to science. What
Kant did was to select the plausible aspects from both the doctrines of
empiricism and rationalism and bind them together into a coherent whole to
account for our knowledge. He upholds the empiricists’ conviction that only
sense experience can provide us with the material for our judgement but he
refuses to accept that formless and meaningless chaos of our sensation which by
itself alone cannot provide the universality of necessity of our scientific judgement.
Kant agrees with
Descartes that the mind has an essential role to play in formulating statements
which are necessarily true but he disagrees with him in that he does not accept
innate ideas which have not somehow originated in experience. Kant also shares
some views with Hume relating to the fact that some knowledge claims go beyond
sense experience. He however disagrees with Hume on his diverstating critique
of causation. To Kant, if Hume’s critique of causation is allowed to go
unchallenged, it will undermine the foundation of our scientific knowledge.
Kant started his
solution to the rationalist’s and empiricist’s debate by positing the question:
“How are synthetic a priori judgements possible?”
v 2/12/10
·
A
triangle is a three sided figure.
·
A
bachelor is an unmarried man
A synthetic
proposition on the other hand is the opposite of analytic propositions in the
sense that the subject term is not synonymous with the predicate term. In other
words, the predicate term adds something to the subject; for example:
·
A
book is on the table
·
Dr.
Oyeshile is in the class.
We can say therefore that there are marked
differences in both types of propositions. For instance, the denial of analytic
proposition will lead to self-contradiction – a bachelor is an unmarried man.
To know whether an analytic statement is true, all we have to do is to analyse
the terms contained in it. Synthetic propositions on the other hand are
dependent on experience or verification for their truth. They are therefore
contingent propositions (dependent propositions).
A priori truths or knowledge are the
truths that are necessary. A truth is knowable, a priori, if it will
necessarily hold true for all cases, today, tomorrow and forever; for instance
the assertion:
·
A
person cannot be in two places at the same time.
·
A
blue car is blue
·
A
black bag is black.
These truths are
independent of sense experience, in other words, they are self-evident and need
no further investigation by further experience. On the other hands, any
statement that we do have to test to see if it holds for future cases is a
contingent statement which is knowable only aposteriori, for instance the
statement:
·
There
is a phone in my bag.
From the
distinction made above, it seems apparent that analytic and a priori
propositions belong to the same class while synthetic and a posteriori are more
or less the same. However, Kant shows that a priori knowledge has larger scope
than we tend to attribute to it. It is largely with the a priori concept that
Kant proffers solution to the rationalists/empiricists conflicts.
·
An
argument that proceeds from cause to effect is called an a priori argument;
deductive reasoning is therefore a priori. Statements, whose truths or falsity
can be deduced without having recourse to experience or experiments are also a
priori statements.
·
Reasoning
which proceeds from effect to causes; which deduce general rules by looking at
patterns is called a posterior reasoning. A statement whose truth can only be
found out by experience is also called a posterior.
F Criticism of Foundationalism
The aim of
foundationalism is unrealistic and indeed impossible. This is because by nature
man is prone to mistakes and he can never have any guarantee of absolute
certainty in knowledge. it is highly improbable that man can ever have any
guarantee against error in his effort to acquire knowledge. Nor can there be
any system of knowledge that would be immune from error, criticism and
skepticism.
If we examine
closely the foundationalist’s theories of Descartes and Hume, we would observe
that both laid emphasis on intuition as the foundation for knowledge and the
guarantee for certainty. The pertinent question here however, is, “how can
objective certainty in knowledge be founded on subjective intuition?” “What is
the guarantee that whatever is subjectively perceived clearly and distinctly
must be true?” “How possible and realistic is Husserl’s transcendental ego?”
v 13/1/2011
F Quine’s Naturalised Epistemology
Quine’s
naturalised epistemology attempts5 to legitimatise human knowledge claim
through the scientific experimental method. Quine, though an empiricist,
nevertheless believes that the search for a foundation of knowledge is a
misguided venture which cannot be realised.
Why is it a
misguided venture?
This is because
human beings are contingent, historical, cultural and biological beings whose
abilities are limited in time and space. Due to this, he proposed a naturalised
epistemology. According to Quine, the traditional task of epistemologists has
been to place science on a solid foundation thereby making science to
ultimately rest on empiricism. Also all our learning and or meaning of words
must ultimately rest on sensory evidence. According to him, “a stimulation of
the sensory receptors is all the evidence anybody has had to go on, ultimately,
in arriving at his picture of the world.”
Epistemology
therefore, going by Quine’s analysis, falls under a chapter in psychology which
is part of natural science and it studies natural phenomenon which is a
physical human subject. This human subject is accorded certain experimentally
controlled input and in the fullness of time, the subject delivers an output
which is a description of the three dimensional external world (present, past
and future) and its history. What Quine wants us to do through naturalised
epistemology is to study the relationship between the meagre input and the
torrential output.
While the old
epistemology attempts to contain science, the new epistemology is subsumed
under science. This new epistemology removes the issues of priority of
epistemology to other disciplines. Quine is also of the view that once we move
away from observational sentences, meaning ceases in general to have clear
application to single sentences and to that extent, epistemology merges with
psychology as well as linguistics and this in effect, blurs the distinction
between analytic and synthetic proposition.
[1]
Common sense
frequently says it is sceptical, but it means simply that it demands to be
shown the evidence – a position not only commendable but necessary for the true
philosopher. When we say “sceptical” in philosophical sense, however, we are
referring to those who refuse to accept even the first principle of the
understanding, even the very existence of the self, as evident and knowable.
To demonstrate the error of skepticism to
the skeptic is impossible because the skeptic refuses to accept the principles
which make demonstration possible. It is no use saying to the skeptic, “At
least you are certain of one thing, and that is that you are not certain of
anything,” or “At least you know that you do not know anything.” All such
propositions imply the validity of the principles of non-contradiction, which
the skeptic refuses to accept.
It is verbally possible to doubt
everything forever. Whether it is actually possible to have a living, real
doubt of everything is a deeper question, and to answer it we must penetrate
behind the barrier of language. The real problem of skepticism is not whether
it is verbally possible to doubt everything but whether it is psychologically
possible; whether, that is, a human being can actually be what the absolute
skeptic says he is. It is not possible to question the sincerity of the person
who calls himself a skeptic but it is legitimate to remind him of the
difference between a verbal doubt and a real doubt and of what is implied by
real doubt.
Real doubt paralyses activity. If you had
a real doubt whether or not your food was poisoned you would not eat it. If you
had a real doubt of the safety of the elevator you would walk. If you had a
real doubt of the destination of your train, you would get out and ask. Of
course, if you had a real doubt of everything you would doubt the very
existence of the food, of the elevator, of the train. You would also doubt,
really doubt, the existence of other people, of your own past, of the immediate
future. If a person really doubted all the evidence of his senses and
intellect, he would be able only to lift his finger as Aristotle puts it. The
absolute skeptic is reduced, in short, to the existence of a vegetable.
This is one check, then, that can be made
against the absolute skeptic. Does he really act as though he had a real doubt
of everything? For if someone asserts a philosophical position as true, it is
legitimate to ask whether he acts in accordance with his asserted philosophy.
[2] Solipsism is the belief that the
only thing somebody can be sure of is that he or she exists, and that true
knowledge of anything else is impossible.
[3]
Induction
(logic), in logic, process of drawing a conclusion about an object or event
that has yet to be observed or occur, on the basis of previous observations of
similar objects or events. For example, after observing year after year that a
certain kind of weed invades our yard in autumn, we may conclude that next
autumn our yard will again be invaded by the weed; or having tested a
substantially large sample of coffee makers, only to find that each one of them
has a faulty fuse, we conclude that all the coffee makers in the batch are
defective. In these cases we infer, or reach a conclusion based on
observations. The observations or assumptions on which we base the
inference—the annual appearance of the weed, or the sample of coffee makers
with faulty fuses—constitute the premises or assumptions.
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