This paper is an attempt to answer one of the most fundamental

questions of philosophy through an analysis of the writings of A.J.

Ayer, R.Chisholm, L. Wittgenstein and the theories of Moore and

Descartes. 



            WHAT IS KNOWLEDGE AND HOW DO WE KNOW THINGS ?



	Epistemology or the Theory of Knowledge is an area of

philosophical inquiry that began with the ancient Greeks and has

intruded upon the present, still unresolved Perhaps, the two most

famous and divergent, schools of epistemology are those of Descartes

and the so called "Sceptics".

	Descarte's construction of the universe can be summarized by

one of the most popular propositions to ever come out of

philosophy, namely "I think threfore I am." This is an interesting

hypothesis but, it does leave some very important questions unanswered

as we shall see later. 

	The Sceptics viewpoint on epistemology as well as the universe

as a whole has a number of formulations that range from the severe to

the unsatisfying. The most common formulation is as follows: 

"I may for all I know be dreaming". Given that one accepts this thesis,

one is therupon presented with very powerful grounds for doubting

things that appear manifest.

	Both of the above formulations serve as cornerstones for

current epistemology.They are used in conjunction with the fundamental

questions in the Theory of knowledge to develop more cohesive and

complete epistemological constructions. The questions which any

reasonable theory must adress include the following:

	

	1. What, if any, is the distinction between knowledge and true

 	   opinion?



	2. How does the concept of evidence relate to knowledge about

	   a proposition ?



	3. What is the difference between a proposition that is

	   self-evident and one that is empirically derived?



	4. How does the truth value of a proposition realte to ones 

	   knowledge of that statement.



	

	A.J. Ayer in his "The Problem of Knowledge" seems to provide a

good first foundation in his approach to epistemology. He firstly,

differentiates between the Theory of Knowledge and the areas of

Lexicography and Scientific inquiry. Epistemology one must remember

ius neutral with respect to particular matters of fact unlike

scientific inquiry. It is neither proved by formal demonstration as in

mathematics nor is it tested  by observation as in mathematics.

	Epistemology is simply an analysis and clarification of

propositions or families of propositions. The manner in which Ayer

wishes us to analyzes propositons can be thought of in this manner:





	"A" knows a proposition "p" if and only if



		1. "A" has true belief of "p"

		2. "A" has the right to be sure that "p"



Where "2" above is defined as:



	1. "p" is self-evident

	2. "p" is warranted by experience

	3. "p" follows from other things of which we have the right to

	   be sure.



	This seems at first glance to be a reasonable formulation of

what we "know", but how does it stand up to more rigorous testing.

Scepticism, being the bane of most philosophies should be dealt with

first. Consider, two forms of the sceptical hypothesis, the so-called

"strong" and "weak" forms:





	Strong form: For all you know, for all p (you think you know)

		     you don'y know p



	Weak form: For all p, for all you know, you don't know p.





	The "strong form" of the sceptical hypothesis is equivalent to

stating that "all x is illusory". This is in fact problematic. If all

x is illusory then all x can not be illusory because there can be no

concept of a true perception of x.

	Ayer's theory hence, has only to deal with the "weak form" of

the sceptical hypothesis. Even the weak from should produce grounds

for doubting Ayer's thesis, especially in the case of something that

is warranted by experience.  Ayer grants that scepticism is right for

a class N pf propositions where this class is all "p" outside the set

of "directly warranted propositions". In other words he disputes the

weak form of the sceptical hypothesis and creates an even weaker

sceptical hypothesis of the form: "For all "p" outside the "directly

warranted" for all you know you don't in actuality know it ." 

	In short Ayer's method of analysis includes a case by case

consideration of each proposition as it appears to him and a similar

refutation of the sceptic.

	Chisolm in his "Theory of Knowledge" takes another attitude in

dealing with epistemology and the ever present sceptic. He begins by

assuming three statements. Firstly, there actually exists something we

know and furthemore that which we know is fairly equivalent to the

class of propositions we think we know. Secondly, our knowledge of "p"

is justified by evidence for "p". Finally, that there exist sets of

principles that govern our use of evidence and our justification for

concluding "p". 

	Chisolm further, goes on to state that what we know about the

universe is actually a hierarchy of propositions, where a set of

propositions act as evidence for another. This hierarchy uses as its

basis a certain class of propositions that are to be considered

"directly evident". That is just the class of propositions "p" for

which the following is true:



	"What justifies me in thinking that a is F is just the fact

			   that a is F"



	Chisolm's weakness comwes in his response to the sceptical

hypothesis. He manages to deal with the sceptic by ignoring him (in a

sense). The sceptic would ask Chisolm "How do you know that believing

that all men are mortal is self-presenting (hence directly evident).

Chisolm's response is , "I know that believing that all men are mortal

is self-presenting." This manner of dealing with the sceptic may leave

a bit to be desired.

	Chisolm's major contribution though is a theory of how we come

to believe things. In this he does manage to put the sceptic to rest.
Chisolm's formulation is as follows. If it is not the case that

witholding belief of a proposition "h" is more reasonable than

believing "h" then believing "h" is more reasonable than believing

"not h". From this thesis, one should believe "h"  just in case the

degree of reasonableness of believing "h" is greater than 1-e where e

is a measure of the degree of caution for that proposition. 

	Chisolm thus contrasts Ayer's thesis in that knowledge does

not have to be "True belief" it just has to be believable "beyond a

reasonable doubt".  Take a situation for example where the correct

anser is "X" most of the evidence suggests "Y" and only a tiny

fraction suggests "X". One can beyond a reasonable doubt conclude that

"Y",given that the warrant for asserting "X" is small enough. One can

then be said to "know Y" even though "X" is true. This appears to be

more in line of how we actually come to "know" something than Ayer's

formulation. 

	Wittgenstein takes a stand against both Ayer and Chisolm.

Chisolm suggests that we start off with the notion of "knowing a

proposition". If though you know a proposition p then you also know

that a sentence s expresses that proposition p. My knowledge of

meaning ('x expresses x) is certain and does not depend on evidence.

It is therefore self-presenting. Chisolm does not consider knowledge

mediated by a sentence that expresses that knowledge.

	Another oversight in Chisolm's work is the failure to discuss

what "having the concept p" really means. Wittgenstein states that

when one speaks of knowing what an "a" is one takes evidence from

one's behavior towards "a".  Chisolm feels that when I speak of

"knowing what a is" arises because certain information is

self-presenting for the person who possesses it.  Take the case of the

triple integral. Surely I know what a triple intyegral is but, not

being a mathematrician can I say that the knowledge of a triple

integral is self-presenting to me? 

	Wittgenstein advances the thesis that with sentences or

statements are associated warrants for the sentence's assertion or

denial. The statement for example, "I am certain that p"

psychologically implies p as contrasted with either Ayer or Chisolm

that take "p" as a seperate statement. Wittgenstein also makes the

point that the differences in two sentences make no difference if it

is seen that both have the same warrant for assertion.

	How does Wittgenstein answer the sceptic? The sceptic would

say, "It is doubtful that I have two hands". Wittgenstein's response

would be simply, "What is the warrant for 'It is doubtful whether I

have two hands' ? There is none, hense the sceptical hypothesis is

nonsense". It appears what gets the sceptic into "trouble" is the fact

that doubting the existance of "x" makes sense for only SOME x not for

all x.

	The final disagreement comes between Ayer and Wittgenstein.

Ayer in addition to stating tyhat philosophy is neither science nor

lexicography advances the propositions that each statement has a

logical form and that this "logic" is an extended form of formal

logic. There is a problem with this though. Consioger the following

statements:



	1. It is doubtful whether I have a bright future.

	2. It is doubtful whether I have a mother

	3. It is doubtful whether I have a hand.



All these statements have the identical logical form yet, they are not

all valid (in fact only #1 is). Wittgenstein shows through these types

of examples that sameness in form can indeed mask differences in

warrants. 

	The concept of warrants for the assertions of statements also

allows us manage differing viewpoints of identical concepts in

different societies. You see the warrants for assertions for a

particular statement arise out of the linguistic environment. Certain

propositions for example, only make sense given that entire grups of

things are accepted as true. This allows us the freedom to know

certain facts conditionally. That is, we can know something just in

case something else is true. Scientific research and language learning

are examples of where the importance of previously "known" information

is crucial. These theories of epistemology are therefore more than

mental or rhetorical exercises. They help us adress some of the

questions how and why we thik in the manner that we do.