




































JOURNAL OF PHILOSOPHY-4TH-EDITION (AQUINO)-2022


Abstract

This work examines some of the sources of human knowledge to ascertain their validity 
and justification. The search of/for the justification of human claim to knowing a 
particular thing brought to bear the need for the re-examination of the sources through 
which this claims emanate from. This is aimed at ascertaining the justification of the 
source to know if such knowledge is reliable. This search over the years resulted in 
bringing forth various opinions and sources as through which humans can gain 
knowledge. Some of these opinions and sources tend to stand in conflict with others there 
by making it confusing for one to actually know which is to be trusted. It is on the bedrock 
of this confusion that the objective of this research is to examine the sources of knowledge. 
To achieve this objective, this work defines knowledge, discusses some of the types, and 
sources of knowledge as well as attempt an evaluation of the sources of knowledge 
discussed. This research is relevant because it aims at putting forward the various 
discussed sources of knowledge and the examination of these sources to ascertain their 
validity. The method employ in writing this paper are philosophical methods of 
examination, criticism and evaluation.

Keywords: Epistemology, Sources, Ratinalism and Empiricism 

Introduction
The human person over the years is bedeviled with the desire to know. This desire 

is an inherent disposition in man that stirs up the incessant curiosity to always desire to 
unravel things: search about the primordial stuff of the universe, the essence of being, his 
existence and other existents in the world. This burning-incessant curiosity is what is 
responsible for man engaging in various forms of study. These studies are geared towards 
also knowing: what is man's place in the world? What is the explanation of the world man 
finds himself? How can man even gain knowledge about his place in the world? What is 
this knowledge? Why should man even seek to know? From what can man gain 
knowledge from? How many kinds of knowledge is there to be known? Are there rules 
governing the process of knowing?

The above questions are all epistemological questions that aim at man gaining 
knowledge about one thing or the other. However, as earlier said, the core focus of this 
paper, is “how does man get to know and what validate his claims that he knows? In other 
words, what are the sources responsible for man's claims of possessing a particular 
knowledge about a particular thing? It is the objective of this paper therefore to examine 
the some of the sources of knowledge that has been put forward is justify their validity and 

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EPISTEMOLOGICAL RE-EXAMINATION OF THE SOURCES 
OF HUMAN  KNOWLEDGE

Glory Nse EDET, and Blessing Ogechi EKEH



acceptability. In doing this, this paper presents some of the weaknesses and strengths 
associated with those mentioned sources. Also, to put forward a better understanding of 
the purpose of this paper, this paper defines knowledge, it discussions some of its types, 
and also looks into how they relate to the sources of knowledge.

Concept of Knowledge
It is the case over the years that knowledge remains an intriguing phenomenon 

and to provide an adequately acceptable definition keeps troubling man even till data. 
This is to say that, there is no univocally acceptable definition of knowledge. On the other 
hand, this does not mean there is no definition of knowledge; of course, there are 
thousands of definitions given so far. Despite these definitions given about knowledge, it 
is important to mention here that a proper definition of knowledge ought to begin with 
explaining the word “know”. This is because, the word 'knowledge' is “… the noun form 
of the very to know” Ibrahim, 2012: 110. Hence, in this paper, we shall begin the 
definition of knowledge from defining what 'know' is.

Idang opined that “to know means to have an idea of something as the result of 
experience, information or learning's and knowledge in its simplest form has to do with 
understanding and familiarity gained by experience or information” Idang, 2008:16, this 
simply means that having knowledge about a thing comes from first having an idea of 
such a thing either through learning about or experiencing it which is a process that has to 
do with the verb 'know'.

On the other had, Chambers Encyclopedic Dictionary emphasizing more on what 
'to know' means averred that:

To know: therefore, can mean any of the following; to 
be aware of something; to be certain about it; to learn 
and remember something's, to have understanding or 
grasp of the: object of knowledge; to be familiar with 
something; to be able to recognize or identify 
something; ability to distinguish between things; to 
have enough experience and training, to be intimate 
with something” Ibrahim, 2012 :110.

From the above views given about 'to know', it becomes clear that since there are various 
opinions about what 'to know'  is, it will be difficult to coin or have a univocal view of 
what knowledge is. This is because different people will define knowledge based on their 
conception and understanding of the word 'to know'.

The above explication was aimed at giving a background to why there is no 
univocal definition of knowledge and to what one may consider to be definition. The 
controversy and disparity in opinion concerning what knowledge is or should be 
considered as did not start today. This controversy has been right from the ancient period 
through the medieval, modern and down to the contemporary period. A historical view of 
what knowledge is will help explain this position better.

In the ancient period as seen in the Thaeatetus, “knowledge was defined as 
perception. The things we perceive constitute what we know” This was the view of the 
man called Thaeatetus as seen in the dialogue Thaeatetus. However, Socrates objected to 

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this position by asking 'can't one be mistaken in his/her process of perception and world 
one still therefore not be justified in claiming to have knowledge since knowledge is 
perception? What Socrates was trying to say was; if perception means knowledge, then, a 
misperception will double as knowledge and non-knowledge at the same time and this 
will be contradictory” (Ibrahim, 2012, p. 111). Thus, Socrates argued that knowledge 
should be something more certain then mere perception. This led to the task of defining 
knowledge by Plato who was a student of Socrates. 

For Plato, knowledge should be something that is true, and is believed to be true 
and there is a rational justification for such belief. This rational justification is the rational 
explanation given to support belief. This led Plato towards comparing what is regarded as 
knowledge and what is regarded as mere belief or opinion. With the take-off point that 
Plato had, he ended up positing that knowledge is that opinion or belief that is true and 
there is a rational explanation given for its. Thus, Plato's definition of knowledge come to 
be regarded as “justified true belief” Idang, 2008:61.

In the medieval period which was the period dominated by the church, dogmatism 
and belief without much recourse to reason, knowledge was seen as that revealed alone by 
God. One is just to believe and have faith without questioning laid down rules, knowledge 
claim or postulations. This was the era that authoritative and revealed knowledge 
flourished.

In the modern period, with the revolution posed by Martin Luther, Descartes came 
up with a seniors level of revolution and refutation of the position of knowledge claims 
held by the church. According to Ibrahim “Descartes, a rationalist of the modern period, 
insisted on a kind of agnostic foundation on which to hinge his entire theory of 
knowledge. Though his systematic or methodic doubt he arrived at the logito… Descartes 
identified the criteria of distinctness and clarity as the marks of true knowledge. Thus, true 
knowledge for Descartes must come from self-reflection, geared by intuition that springs 
from pure light of the human mind and deduction.

Contemporary thoughts about knowledge tend to show that there are some 
elements of disagreements found between the ancient view and some of the contemporary 
period. For instance, Edmund L. Gettier in an article published 1963 titled “Is justified 
tree belief knowledge?” put forward, position that tends to rival the claim that knowledge 
is justified true belief held in the ancient period. He argued that, though justification, truth 
and belief are necessary conditions for knowledge claim, they are not sufficient 
conditions. He showed through two thought experiments how weak the 'justified true 
belief' account of knowledge is without a fourth condition to support it. Though he did not 
give the fourth condition, he set the pace for the search of the fourth condition in his new 
and more powerful way.

Despite the search for the fourth condition, Omoregbe asserted that “knowledge 
presuppose consciousness. All thinking, all acquisition of knowledge, and even 
skepticism itself presuppose consciousness” Omoregbe,1998:1. Thus, it can be said that 
knowledge for Omoregbe deals with one's consciousness of a particular thing or event. 
Omoregbe further buttressed his point by evening that:

Consciousness is basic to epistemology and is the 
veritable starting point for any discussion about 
knowledge. For, it is because man has consciousness 

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(reflective consciousness) that he can think, that he 
can acquire knowledge, can justify his knowledge or 
can even doubt.

From the above therefore, it appears for Omoregbe, knowledge about a particular is 
synonymous with consciousness or being conscious of that particular thing. From the 
foregoing, this research submits that knowledge is the familiarity, consciousness, claim 
and awareness one has about a particular as a result of experience, reasoning or fearing 
that can be rationally justified.

Some Types of Knowledge
The following are some of the types of knowledge there are:
1. Empirical Knowledge 
This is the type of knowledge that is derived through the sense organs like: the sense of 
seeing, learning, touching or feeling and tasting. Omoregbe posited that “empirical 
knowledge is the knowledge acquired through sense. Perception, that is, through any of 
the five senses. Empirical knowledge is always knowledge of an individual object, a 
particular object, not knowledge of a class or category of object” Omoregbe, 1998:24. 
Those philosophers who subscribe to this form of knowledge are called 'empiricists' and 
“this position in epistemology is known as empiricism' Idang, 2008:6. In a nutshell, 
empirical knowledge is that knowledge derived from observation, experience or 
experiment which is strongly aided by the human senses like; the eye, ear, hand, leg or 
other part of the body, nose, tongue etc.
2. Rational Knowledge 
This is the opposite of empirical knowledge. Rational knowledge is the knowledge that is 
based on reason. Asira, Ogar and Ibrahim postulated that rational knowledge is “any 
knowledge that is based on rational grounds like on reasoning, logic, mathematical 
procedures and other extra-sensory means that are not based on capricity, chance, lunch, 
or based on sheer imagination” (Asira, Ogar and Ibrahim, 2012, p. 41). In epistemology, 
this kind of knowledge falls under the school of thought called 'rationalism'.
3. Authoritative Knowledge 
This is the knowledge derived from an authority or a secondary source. Idang submits 
that:

The knowledge me acquire when we depend on a 
secondary source for information is said to be 
authoritative knowledge. For instance, we come know 
about Socrates by the testimony of his friends, pulpits, 
and contemporaries like Plato and Aristotle… 
authoritative knowledge is closely related to revealed 
knowledge, which is also certified by an indisputable 
authority (Idang, 2008, p. 63-64).

From the opinion of Idang, despite his claim that authoritative knowledge is closely 
related to revealed knowledge, this paper observes that it is also closely related and 
similar to testimonial knowledge.

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4. Intuitive Knowledge 
This type of knowledge is the type that is derived through a moment of insight and 
awareness. Idang averred that “the position on intuitions thus seems to be a supre-rational 
approach to truth based on a spontaneous apperception of reality” (Idang, 2008, p. 65). It 
should be borne in mind at this point that intuition is not the result of conscious reasoning 
or of immediate sense perception, but a moment of flash. 
In Omoregbe's view:

Intuitive knowledge is knowledge gained by intuition; 
it is knowledge that is acquired directly by an 
immediate contact of the mind with the object without 
going through the process of reasoning. Such 
knowledge is acquired by direct insight without 
making use of reasoning or concepts. It comes as a 
flash into the mind (Omoregbe, 1998, p. 29).

5. Conceptual Knowledge
Conceptual knowledge is defined as the knowledge that is based on universal concepts 
“acquired through the process of abstraction; hence it is also known as abstract 
knowledge or intellectual knowledge” according to Omoregbe (Omoregbe, 1998, p. 34). 
The process of abstraction is the process whereby abstract ideas are abstracted from 
particular concrete objects. 

For Hamlyn  “Understanding conceptual knowledge is linked up with the fact of 
language” (Hamlyn, 1970, p. 272). This is because, concepts are words and words are 
units of meaning or building blocks in mean information within a given language. This 
“using a concept means understanding the grammar of the language in which the concept 
is used. Wrong use of concept will obfuscate meaning and hinder communication and 
ultimately hinder knowledge” (Asira, Ogar and Ibrahim, 2012, p. 145).

Some Theories of the Sources of Knowledge
There are many theories of knowledge; but two of these theories are very 

outstanding. They are rationalism and Empiricism. This paper shall focus on the 
examination of these two theories with at least one other one:

1. Rationalism:
This is an epistemological doctrine that holds that knowledge comes through 

reasoning. Esikot postulated that “rationalism is the school of thought that holds that 
knowledge of the real world is acquired independently of experience” (Esikot, 2019, p. 
33). In other words, this position stands against the senses as a source of knowledge. Thus, 
rationalism is opposed to any form of knowledge that comes from the sense or experience. 
Those philosophers who support this view are called 'rationalists'. For Esikot: 

They contend that there are some truths that accessible 
to the human mind and these constitute the only 
reliable foundation to our knowledge claims. Such 
truths are evident in geometry and logic (Esikot, 2019, 

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p. 33).

From the above therefore, rationalism is that theory of knowledge that is against sense - 
perception. Another name for this theory is 'a priori' theory of knowledge.
2. Empiricism
Empiricism is that epistemological doctrine that holds that knowledge is derived through 
the senses and experience. For Esikot:

The central thesis of empiricism is that perception is at 
some point or other indubitable; hence some forms of 
knowledge, if not all knowledge, come ultimately 
from experience (Esikot, 2019, p. 32).

Hamlyn held similar opinion when he averred that: 
Thus empiricism in its strongest version comes down 
to the thesis that the indubitable propositions that must 
form the basis of the defense of knowledge against the 
skeptic are to be found in experience (Hamlyn, 1970, 
p. 37).

From the above two definitions, generally expressed, empiricism is the philosophical 
doctrine that holds that human knowledge (of the world) is acquired totally from the 
senses and experience. Thus, observation is said play a vital role as long as this position is 
concerned. Those philosophers who subscribes to this position are called empiricists.
3. Intuitionism
According to Mbat (Mbat, 2003, p. 38), “intuitionism is a philosophical doctrine that 
knowledge by intuition is the primary and only source of knowledge”. In other word, this 
position argues that the only true source of knowledge is institution. This kind of 
knowledge does not depend either on the senses, perception or on reasoning.

Some Sources of Knowledge
According to Esikot, “sources of knowledge refer to the ways or medium though 

which we come to acquire or possess knowledge” (Esikot, 2019, p. 31). There are a lot of 
sources through which human can know a thing. The following are some of those sources:
1.  The Senses (Empiricism)
One of the sources of human knowledge is the senses like the eye, nose, mouth, lands etc. 
the philosophical position that supports the senses as a reliable source of human 
knowledge is called empiricism. Mbat postulated that empiricism as an epistemological 
theory holds that “all our knowledge derived from, or are founded in our sense perceptual 
experiences, which include touch, smell, hearing, taste and sight” (Mbat, 2003, p. 36). 
This position in nutshell holds that, the senses is the only means through which humans 
can gain knowledge about reality. Some philosophers who support this position are: John 
Locke, Bishop Berkeley, and David Hume. In the opinion of Esikot:

Modern empiricists are of the view that all 
propositions that can be known are related in some 
way to experience apart from the propositions of logic 

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and mathematics, which depnd for the truth on the 
meanings of the terms involved; but that we are not 
really provided with new information by means of 
them (Esikot, 2019, p. 32).

2. Reason (Rationalism)
Reason is acclaimed as one of the sources of knowledge, perhaps, to some 

philosophers, it is the only true source of knowledge. Reason or reasoning as a source of 
knowledge is opposed to sense-perceptual experience. Reason as a source of knowledge 
falls under the epistemological school of thought called rationalism. Mbat posited that 
“rationalism is a major rival school of epistemology to empiricism. Rationalism is the 
claim that true knowledge is derived from reason” (Mbat, 2003, p. 37).  In other words, 
rationalism challenge physical sense-perceptual experience as deceptive. Rationalism 
holds that possible-certain truth about anything one wishes to know; including the 
ultimate nature of reality, the laws of nature, essence of God and moral laws can be known 
through reason.

4. Authority
Another source of knowledge that is worthy of note here is authority. Esikot averred that 
“by knowledge from authority we mean such kinds of knowledge that we acquire from 
person other than ourselves” (Esikot, 2019, p. 33). It should be understood that an 
authority is an expert in a particular field or discipline whose pronouncement or opinion is 
often considered as trustworthy and valid. Mbat posited that:

A good lot of the things we claim to know are neither 
things that we personally experience nor they are 
things that we infer from our reason. Besides knowing 
certain facts through experience and reason, 
authoritarians claim that we can also know facts about 
the world by learning them from some authority 
(Mbat, 2003, p. 39).

Evaluation
From the foregoing, it is apparent that the lack of a univocal definition of 

knowledge may not be unrelated with the fact that there are various sources of knowledge 
and types of knowledge as well. This is so because, in as much as there are a lot of 
positions given on how humans can gain knowledge, one should expect that there will be 
accompanying varieties of definitions of knowledge. Be that as it may, this paper mainly 
focuses on the sources of knowledge.

There are other sources of knowledge that has been postulated, but this paper 
submits three for examination because of the following reasons: 

1. Not to go off the scope and limit of this work.
2. The other sources of knowledge; when critically analyse, studied and examined 

are seen to (in one way or the other) fall under these aforementioned three sources.
The above discussed sources are not without flaws even as they are tenable to a large 
extend. As one of the objectives of this paper, an examination of these sources will be 

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carried out at this juncture to ascertain their weaknesses and strengths. Let's begin with 
empiricism (the senses). 

Empiricism stands very tall as long as knowledge acquisition is concerned. This is 
because, whatever one claims to know, such must have passed through the process of 
observation, either directly by the one who claims to have the knowledge or by some other 
person who serves as an authoritative figure (authority) from which such claim emanated 
from. Thus, one cannot totally get rid of the senses in the process of knowledge 
acquisition. However, as Esikot argued: 

The acceptance of empiricism either in the traditional 
or modern rendition rules out certain claims to 
knowledge. For instance, knowledge of the soul, 
God… one problem with empiricism is that it is 
restricted and limits that which is knowable to 
perception, and perception is not reliable (Esikot, 
2019, p. 32).

In other words, Esikot is arguing that since the senses is associated with perception, and 
perception may be deceptive because of the weakness of the senses, empiricism may also 
be misleading since it depends on the senses. Mbat held and raised similar contemplations 
about the validity and justification of the claim of knowledge from the senses when he 
averred that:
While it may not be right for us to deny the facts that experience provides us in formation 
about the physical world, and serves as source for our formation of ideas… empiricism 
has some serious problems. For example, Descartes… questioned: if we have for one time 
been deceived by our senses, what guarantee do we have that they may not always 
deceived us? (Mbat, 2003, p. 36).

On the other hand, rationalism and authority as sources of knowledge are not with 
flaws. For instance, rationalism discard the senses in the process of knowledge 
acquisition forgetting that one cannot reason or think about nothing. One must have seen 
something, touched it, smelt it, felt it or heard about such a thing before contemplating or 
rationalizing an such a thing. As such, the senses cannot be totally thrown away for they 
are the medium through which such is possible. Thus, rationalism may not function 
effectively well without the senses.

On authority, it is believed that the authority must have derived his/her facts or 
foundation of knowledge from either the senses or reason. As such, authority as a source 
of knowledge is still linked back to the senses or reason. Despite this, when the reliability 
of knowledge from authority disagrees with another authority on the same claim, there is 
need to be cautions by withholding judgment on the matter. Furthermore, sometimes it is 
seen that a careful examination of the claims of an authority unravels some weaknesses of 
such claims, thus, one must be careful when accepting knowledge claim based on 
authority.

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Conclusion
In conclusion, this paper submits that as controversial as the definition of 

knowledge is, there is still a definition of knowledge based on the school of thought one 
subscribes thought. This school of thought is also influenced by the believed one holds as 
his or her source of knowledge. Be that as it may, there are two foundational sources of 
knowledge which humans subscribe to; they are empiricism and rationalism. The former 
emphasizes the senses; the latter emphasizes reason. A careful examination of these two 
sources shows that man cannot do without them. At some point man makes use of reason 
and at another time he makes use of the senses; whether consciously or unconsciously. 

 
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