The Move From Doubt To Certainty; A Look Essay, Research Paper
The Move from Doubt to Certainty; A Look
at the Theories of Descartes and Locke
Descartes is interested in the certainty of his
existence and the existence of other people and things.
Descartes’ beliefs vary from those of Socrates. Descartes
argues that knowledge is acquired through awareness and
experience. Using this approach, Descartes moves through
doubt to certainty of his existence. He asks himself
various questions about the certainty of his existence and
solves them through clear thought and logic. Using this
method Descartes establishes doubts to be truths and by the
end of the book, he has established that he does indeed
exist. In this paper, I will show how Descartes moves
through doubt to certainty. I will explain how Descartes
uses the cogito, proves the existence of God and what that
means to his existence. I will also discuss the general
rules of truth that Descartes establishes.
In the First Meditation Descartes begins to examine
what is certain and what is doubtful. Descartes wants to
establish that his knowledge is certain and not doubtful.
…I had accepted many false opinions as being
true, and that what I had based on such insecure
principles could only be most doubtful and
uncertain; so that I had to undertake seriously
once in my life to rid myself of all opinions I
had adopted up to then, and to begin, and to begin
afresh from the foundations, if I wished to
establish something firm and constant in the
By this Descartes means that he wishes to establish a
foundation for his knowledge based on certainty instead of
doubt. Descartes first looks at the senses. This is
important because the senses are the first thing to cause
doubt. He focuses on the perception of things. He says that
things far from him, in the distance, give him reason to
doubt their certainty, while things that are close to him
are indubitable and he is clear about their certainty.
However, Descartes realizes that dreams pose an
obstacle to his beliefs. Even up close, dreams can be
indubitable. Descartes believes that if a person has had a
dream that was so intense that the person could not
determine it form reality, then they have reason to doubt
objects that are close to us and appear to be indubitable.
In order to resolve this problem, Descartes suggests that
one must examine whether they are dreaming or not.
Descartes realizes that he can not rely on his senses
anymore to give him dubitable truths. He turns to find
something that is indubitable. Descartes tries to use
science as a foundation for truth. He discards physics,
astronomy, and medicine because all three of them rely upon
the senses. “…we shall not be wrong in concluding that
physics, astronomy, and medicine, and all the other sciences
that depend on the consideration of composite things, are
most doubtful and uncertain…”(Descartes 98). However,
Descartes finds that such things as geometry and arithmetic
can be trusted because their are no senses involved. They
are based upon logic.
“…whether I am awake or asleep, two and three
added together always makes five, and a square
always has four sides; and it does not seem
possible that truths so apparent can be suspected
of any falsity or uncertainty”(98).
However, Descartes finds reason to even doubt this.
The only thing that could makes these truths dubitable is
through the intervention by an Evil Deceiver (God).
Descartes cannot prove that God is good and has to
acknowledge that God has the power to deceive. Therefore,
Descartes must doubt all things until he can prove their
certainty. Descartes comes to call this doubt Universal
In the Second Meditation, Descartes examine the
existence of himself. He concludes that if he cannot prove
something exists then how does he know with certainty that
he exists. It is his doubt of his existence that Descartes
uses to prove his existence. Descartes realizes that if he
is able to doubt then he does indeed exists. He take the
approach that, “I think therefore I am” to establish a
certainty that he exists. This idea also known as the
cogito becomes the central point that Descartes will use for
the remaining of his meditations. Descartes affirms his
existence every time he thinks, doubts, or is
persuaded(Descartes 103). Descartes affirms that if there is
an Evil Deceiver then Descartes must exist because in order
for God to deceive, Descartes he must first exist.
Although, Descartes has proved his existence he can
only prove it in the mental capacity. He does not know for
certain that he exists in the physical form. The only way,
at this time, that Descartes can prove the existence of his
body is through his senses. He has already established that
his senses are dubitable and therefore cannot tell him with
certainty that his body exists.
In order to get a better understanding of his
relationship between his body and mind, Descartes melts a
piece of wax. He observes the wax in two different states,
the first in a solid form and the second in a melted form.
He questions how his senses can show him two entirely
different forms of the same substance; yet he knows that the
substance, in both states, although completely different, is
wax. The mind was able to understand the essence of the
wax. Although the senses were not entirely capable of
making the connection between the two forms of wax, the
senses assisted the mind in determining what the substance
was. This experiment proves to be important to Descartes
because he is able to make a link between the senses and the
Using his experiment, Descartes enters his Third
Meditation using his general rule of truth that “…all
things we conceive very clearly and distinctly are
true”(Descartes 113). However, there is one flaw to his
thoughts. If God is an evil deceiver than this cannot be
true. Descartes proceeds to establish that God is good and
does not deceive.
Descartes uses three points to establish the existence
God. These points are ideas. The first one is adventitious
ideas; those ideas that come from outside experiences. The
second is invented ideas; those that are derived from the
imagination such as sirens and chimera. The final is innate
ideas; those that are within one when they are born.
Descartes uses two more points to further establish that God
He uses the ideas of “infinite” and “perfect”. These
two ideas, Descartes cannot account for. The only way for
such things to come about would be from an infinite and
perfect being such as God. These ideas have a direct
relationship with God. In order for a finite beings such as
Descartes to have a concept of infinite it must have been
planted there by an infinite being such as God. Descartes
concludes this idea to be true because one cannot derive the
idea of infinite by negating the finite(Descartes 125). An
example of this would be the use of a number line. The
number line will never be able to illustrate infinity. One
could negate every number on a number line and still not
arrive at infinity.
Therefore, Descartes concludes that God does exist and
therefore is not an evil deceiver. Because God has supplied
us with the innate ideas of perfection and infinity, God,
therefore, must be infinite and perfect. Descartes states
that, “Whence it is clear enough that he cannot be a
deceiver, for the natural light teaches us that deceit stems
necessarily from some defect”(Descartes 131). Since God is
perfect he is not an evil deceiver.
It is important to realize that by the time Descartes
has reached his Fourth Meditation he has proved three
important things. The first is that doubt is not universal.
The second is that there is a general rule of truth. The
third is that God exists and cannot be an evil deceiver.
However, Descartes raises a question: If God exists and
cannot be an evil deceiver then why are humans imperfect and
perpetually making errors? Descartes explains this through
the explanation of free will.
Descartes states that God has given all humans free
will. This is the cause of human error. Because we have
free will, humans are able to make choices and decisions
free from the influence of God. Sometimes free will
interferes with God’s ability to help humans and therefore
humans sometimes make poor decisions. If God did not give
humans free will than God would play a direct role in every
decision made by humans. It is because God gives humans
free will that allows for human error.
Descartes Fifth and Sixth Meditations begins with the
establishment of his remaining doubts and the application of
what he has discovered. The first question deals with the
essence of color, mathematical, and geometrical truths. The
second is the existence of people and things. The third is
determining the difference between dreams and reality.
Descartes reiterates that God is not an evil deceiver and
therefore he can clearly conceive something to be true. He
reiterates that if he conceives God correctly then God is
perfect. Imperfection is not compatible with God’s
omnipotence. A non-existent thing cannot be perfect. Even
a non-existent perfect thing is imperfect and all perfect
things are perfect. Descartes also restates that a perfect
thing cannot deceive. With this knowledge, Descartes
proceeds to solve his second problem.
The existence of corporeal(physical things) exist with
certainty. Since God is not an evil deceiver, the idea of
physical things is accurate. Although some perceptions will
still be blurry and may confuse Descartes objects do indeed
exist. He concludes that he just has to be more judgmental
of those perceptions.
But as concerns other things, which are either
only particular, as,, for example, that the sun is
of such a size and shape, etc., or are perceived
less clearly and distinctly, as in the case of
light, sound and pain and so on, although they are
very doubtful and uncertain, nevertheless, from
the fact alone that God is not a deceiver, and has
consequently permitted no falsity in my
Descartes now knows for certain that he has a body.
Descartes realizes that, “…I have a body, which is ill
disposed when I feel pain, which needs to eat and drink when
I have feelings of hunger or thirst etc.”(Descartes 159).
Because of these feeling that Descartes has and because God
is not an evil deceiver than Descartes is indeed lodged in a
body and is an entire entity with it.
Descartes finally analyzes his third doubt. He now has
the ability to distinguish between being awake and dreaming.
When we are awake, Descartes states, are mind flows in an
uninterrupted, continuous sequence. When we are dreaming,
our mind does not flow in a consistent, and undisturbed
sequence. When a person has a break in the consistency of
events, they are dreaming.
…when I perceive things which I clearly know
both the place they come from and that in which
they are, and the time at which they appear to me,
and when, without any interruption, I can link the
perception I have of them with the whole of the
rest of my life, I am fully assured that it is not
in sleep that I am perceiving them but while I am
After establishing certainty to his doubts, Descartes
states, “And I must reject all the doubts of the last few
days as hyperbolic and ridiculous, particularly the general
uncertainty about sleep, which I could not distinguish for a
wakeful state…”(Descartes 168). With that Descartes
concludes his meditations and uncertainties.
Although Descartes makes a sound argument there were
some people that disagreed with his theories. One of those
people was John Locke. The beliefs of Locke, who was an
empiricists, were similar to those of the Sophist during the
time of Socrates. He argued that when a person was born
their mind was empty. A person obtained knowledge through
experiences. He also felt that if a person misinterpreted
an experience it could lead to doubt or skepticism. Locke
tries to prove Descartes wrong by saying that there are no
innate ideas. He states that by understanding our own mind
we can deter doubt.
Locke proposes three separate possibilities about
truth. The first is that there is no such thing as truth.
The second is that there is no way to obtain truth. The
third reason is that we can understand implied things but
not be absolutely certain about them. Locke believed that
we never deal with certainty and everyday we deal with
…and it will be unpardonable, as well as
childish peevishness, if we undervalue the
advantage of our knowledge and neglect to improve
it to ends for which it has given us, because
there are some things that are set out of the
reach of it.(Locke 57).
Locke states that not all innate ideas come from
“natural ability”. He says that a universal consent does
not prove innate ideas. They could arise from experience.
Locke supports this theory by saying that innate ideas are
neither in children nor idiots. If these ideas were innate
then everyone would have them. He further states that
mathematical truths are learned from experience and are not
Descartes and Locke were two men with completely
different views. They each set out to prove their own
existence in a different fashion. Although they do not
agree with each other, each one of them presents a clear and
intelligent argument. It is these arguments that have
encouraged the human race to consider the possibility of
existence long after the death of Descartes and Locke.
People will continue to debate their viewpoints for years to
come and maybe, one day we will know the meaning of
Descartes, Rene. Discourse on Method and the Meditations.
Trans. F.E. Sutcliffe. New York: Penguin, 1996.
Locke, John. An Essay Concerning Human Understanding. ed.
Roger Woolhouse. New York: Penguin, 1997.