Lesson 5 - RATIONALISM
Arnel O. Rivera
Based on the presentation of:
Mr. Alexander Rodis
TWO MAIN THOERIES ABOUT THE
BASIS OF KNOWLEDGE
Where does knowledge come from?
What is the basis of knowledge?
Traditionally, philosophers have generally answered these
questions in two ways:
Those philosophers who have emphasized “reason” as the
source of knowledge (inside-out philosophers). This
position is often called rationalism from Latin word, “ratio”
which means reason.
Those philosophers who have emphasized “experience” as
the source of knowledge (outside-in philosophers). This
position is called empiricism from the Greek, “empeiria”
which means experience.
DETERMINE WHETHER THE SOURCE OF KNOWLEDGE
IS REASON OR EXPERIENCE
I know that water is liquid.
I know that gravity exist.
I know that the Earth is spherical.
I know that I exist.
I know that God exists
I know that swans are white
I know that there is love.
I know that this table exists.
I know that man has soul.
I know that all barking dogs bark.
I know that justice is good.
I know that I will rain tomorrow.
I know that there is energy in matter.
I know that all men are equal.
I know that the sun is hot.
REASON AS BASIS OF KNOWLEDGE
Rationalism is the belief that at least some knowledge
about reality can be acquired through reason,
independently of sense experience.
Rationalist believes that some knowledge about reality
can be acquired through reason alone. What they insist
on is that at least some of the truths about reality and
usually the most important truths about reality are
known apart from sense experience.
The rationalist claims that at least some propositions
which are about reality may be known independent of
sense experience and through reason alone.
THE RATIONALISM OF PLATO
Plato believed that the reason, which distinguishes humans from
the lower animals, comprises the essential nature of the human
Human good and happiness lie in the activity and fulfillment of
the rational faculty. That is they lie in the contemplation of
Plato believed that the only proper object of knowledge, or the
only thing that can really be known, is Being. This means that we
can have no real knowledge of the world about us, the relative
and fluctuating world of Becoming where we have only opinion
and not knowledge.
Sense experience is disdained as a hindrance to real knowledge
and true reality by its very nature as transcendent and non-
sensible, can be grasp adequately by the intellect alone.
PLATO’s rationalism is that knowledge is possible only because
it is INNATE, that is inborn.
THEORY OF INNATE IDEAS.
Let us the following statements:
Every event must have a cause.
It is morally wrong to kill people for the fun of it.
All individual are endowed with basic rights.
Do you possess any universal and certain knowledge
about reality? Think of some possible examples.
THEORY OF KNOWLEDGE AS
Plato believed in the preexistence of soul on the grounds
that we have in our minds certain ideas that we could not
possibly have derived from sense experience alone.
Plato believed that the only way to account for this
knowledge is that prior to its embodiment in this world,
the soul was in the presence of the FORMS, where it
acquired knowledge of the realities.
This knowledge was lost or forgotten through the trauma of
birth, though to some degree “recollected” subsequently to
birth on the occasion of our experience or encountered
imperfectly in the sensible world.
RATIONALISM OF DESCARTES
DESCARTES’ TWO FOLD BASIS OF KNOWLEDGE
He is more attracted to mathematics because the truths
of mathematics and the proofs of geometry are certain
because they are untainted by the tentativeness and
fluctuations and relativeness and illusions of sense
He conceived of a geometrical method of philosophy.
He reduced it to two operations of the intellect:
The faculty by which the truths are grasped immediately by
direct awareness, without the intervention of sense-
experience or other ideas.
It is a direct and immediate knowledge of something, which
means that knowledge are not mediated or passed along
through sense experience or through other ideas.
The intuition is not only capable of knowing logical truths
but also truths about reality:
“Every event must have a cause.”
“It is morally wrong to kill people.”
“All individual are endowed with basic rights.”
INTUITIONISM as a theory about the basis of knowledge is
the view that such truths may be known immediately and
Our knowledge is not limited to intuitions and it is
possible to deduce further ideas and truths from our
The faculty by which subsequent truths are known with
necessity from intuited truths, or from intuited truths
taken together with other deduced truths.
By the faculty of deduction, we are enabled to expand
from original intuition our knowledge indefinitely but
without loss of certainty.
It consist of an inference of one proposition from others
and in valid deductive reasoning, if the premises are
true, the conclusion must be true.
LET:US CONSIDER THE FOLLOWING ARGUMENT:
It is immoral to kill persons.
Capital punishment is the killing of persons.
Therefore, capital punishment is immoral.
Deduction is the process by which we draw a conclusion
from one or more premises and if the premises are
true, the conclusion must be true.
The proposition which follows from the others, that is,
the something to be shown, is called the conclusion
The propositions from which the conclusion follows,
that is, the evidence, are called premises.
DISCOURSE ON METHOD
Descartes presented rules which ensure that the intellect will eventually,
grasp all that can be known:
1. The first of these was to accept nothing as true which I did not
clearly recognize to be so: that is to say, carefully to avoid
precipitation and prejudice in judgments, and to accept in them
nothing more that what was presented to my mind so clearly and
distinctly that I could have no occasion to doubt.
2. They second was to divide up each of the difficulties which I
examined into as many parts as possible, and as seemed requisite in
order that I might be resolved in the best manner possible.
3. The third was to carry on my reflection in due order, commencing
with objects that were the most simple and easy to understand, in
order to rise little, or by degree, to knowledge of the most complex,
assuming an order, even if a fictitious one, among those which do not
follow a natural sequence relatively to one another.
4. The last as in all cases to make enumeration so complete and reviews
so general that I should be certain of having omitted nothing.
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.