Rene Descartes methodic doubt

INTRODUCTION
The notion of how knowledge is acquired has continue to chose a fundamental controversy in Philosophy which has led to the emergence of two schools of thoughts; the rationalists and empiricists. The former affirms the acquisition of knowledge through reason unaided by experience while the later adhered to sense experience as the means by which knowledge is acquired.
Despised this two conflicting doctrines, Immanuel Kant tries to reconcile or rather is swift to strike a balance. Between these two schools of thoughts knowledge can be acquired through both ways.
However, in line with these opposing doctrines their surveys seeks to examine the rationalists view of this notions in a particular respect to one of the Philosophers namely Rene Descartes. Rene Descartes is our key study in this work and will look into  his major philosophical work concerning knowledge.
More so, in order to have a better understanding of our subject at hand, this work will give us an inkling of some of the terms on which our topic lies on, by this, it shall avail us the chance to a better understanding. Empiricism is that theory which holes that experience is the source of all knowledge, which thereby denies that human being posses inborn knowledge; while Rationalism is that philosophical view which emphasizes the ability of human reason to grasp fundamental truths about the world without the aid of sense impressions.
CLARIFICATION OF TERMS: Empiricism and Rationalism.
Empiricism is derived from the Greek word “emperia” meaning experience. In this sense, it has both a common sense popular sense and a technical; more oppositely epistemological dimensions.
In the popular usage, empiricism describes a hardheaded refusal to be swaged by anything but the fact the thinker has observed for himself, a blunt resistance to received opinion or abstract reason.
In its most general sense, empiricism holds that all knowledge come from, and must be tested by sense experience.
Rationalism:
Generally, the term rationalism refers to any view appealing to reason as a source of knowledge or justification. In this sense, the term applies to the doctrine that true and absolute knowledge is found only in reason.
Reason, in this sense, refers to man’s cognitive powers generally and is hence opposed to articles of faith and grace. In opposition to the empiricists claim that all knowledge of fact stems from perception, the rationalists argued at knowledge arises through direct apprehension of the intellect; in knowledge acquisition, the faculty of reason lays hold of truth beyond the reach of sense perception, both in certainty and generality.
DESCARTES METHOD OF PHILOSOPHY:
Rationalism is a theory which emphasize that the acquisition of knowledge is through reasoning. This theory opposes empiricism which lay emphasis on sense experience as the source of acquiring knowledge.
In defending the theory of rationalism, there are three representatives of the rationalist school of thought. These three Thinkers are : Leibniz, Baruch Spinoza and Rene Descartes who happens to be the subject of our discussion.
Descartes deny the fact that human knowledge is gotten from sense experience. His belief in innate ideas which he said cannot come from experience of constructed or invented in one’s imagination. He brought up two issues to back up his arguments  which are God and Mathematical objects.
DESCARTES METHODIC DOUBT:
As we mention earlier Descartes decided to set aside all the confusion and uncertainty of the past and to start philosophy afresh. Since the cause of his confusion and uncertainty in the past was in the view of Descartes philosophy which was on a weak foundation and so Descartes decided to reconstruct philosophy on a solid foundation, that is, the fundamental truth beyond human doubt. To begin with everything which was previously known which could be put to doubt is to be set aside. And he quoted “I thought that it was necessary for me to adopt an apparently opposite course and to reject as absolutely false everything concern which I could imagine the least ground of doubt in order to see whether afterward there remain anything in my beliefs which was entirely certain. (Joseph.). The senses are unreliable, they sometimes deceive me, and therefore I cannot be sure that what I perceive with the senses is true and certain. “I doubt everything that I used to know or believe. I am not even sure any more that (2+2 =4) because it is possible that an evil spirit is deceiving me and making me belief that mathematical prepositions are true”.
SPACE AND TIME
Space according to Descartes is inseparable from the material substance that occupies it, since the essence of material substance is extension and every space is occupy by substance. It follows that can be nothing else than man the extension of material substance. There is no material substance that occupies space nor is there any space that is not occupied by material substance. Hence there is no such thing as vacuum or an empty space.
Like Aristotle, Descartes consider time as the measure of motion. And motion, according to him, is the transference of one thing from the vicinity of other thing which is in close contact with it to vicinity of other thing. When one corporal substance leaves the vicinity of certain corporal substance to the vicinity of others, it is said to have undergone motion. God caused motion in the world when he created it, and the amount of motion in the world is constant. Neither increasing nor decreasing.
EXISTENCE OF GOD
The idea of a perfect being, called God, to Descartes can only be innate. He argued that, that idea has properties which do not appear in our experience. The knowledge of God is something that is inborn and so automatically sticks, to the mind without someone experiencing it first before knowing it. Everybody in this world has never seen God but yet, belief that God exists. This is because we have the innate knowledge of God and though we have never experienced Him (GOD), we belief of His existence.
If we were to experience God first before believing in His existence, then no one would even belief up to date because none have ever seen Him. That is why if we depend on experience as the source of knowledge, then there would be no knowledge. (Samuel p.80).
MATHEMATICAL OBJECTS.
This is the second argument Descartes brought in order to back up the argument on knowledge through reasoning under innate idea. Any circle we see is not perfectly round but the circle we think about is perfectly round. In other words, when we reason, then it is perfectly round (with that reasoning, we came to know that circle are shaped round, and not only round but perfectly round.
Descartes also brought a point of clarity and distinctness. To him, “There are even some people who in their entire life, perceive nothing, so accurately as to be able to judge of it properly. For the knowledge on which a certain and incontestable judgment can be formed, ought not only to be clear, but distinct as well…”. Descartes gave an example pertaining the clarity and distinctness that an idea which is clear but not distinct is an experience that is so vivid or forceful which we cannot avoid being aware of it, but at the same time we are not certain of what we are experiencing. On a toothache, the experience is clear, one is forced to be aware of it, but one is not certain of what the ache is or where it is, whether in the tooth or in the mind. Descartes belief that the pain is not from the tooth but rather, the mind. It is not from experience, it is from reasoning.
Intuition and deduction to Descartes are two methods that are the most certain routes to knowledge. Any approach other than this, to Descartes should be considered as suspect of error and dangerous. Intuition is an intellectual activity or vision of such clarity that it leaves no doubt in the mind. It is by intuition that we know one truth from another because it gives us not only clarity, but truths about reality.
Deduction on the other hand, similar to intuition is described by Descartes as all necessary inference from facts that are known with certainty. What makes deduction similar to intuition is that they both involve truth. By intuition, one grasp a simple truth completely and immediately, where as one arrives at a truth by a process (continuous and uninterrupted action of the mind) in deduction. Different from syllogism, deduction indicates the relationship of truth to each other rather than relating concepts to each other as syllogism requires.
THE RATIONALISM OF DESCARTES
Descartes method consists of harnessing the abilities of the mind with a special set of rules. He insisted upon the necessity of method, and upon systematic and orderly thinking. He was appalled at scholars who sought aimlessly for truth, and he compared them to people who, “burning with an unintelligent desire to find treasure, continuously roam the streets, seeking to find something that a passerby might have chanced to drop”. He continues that “it is very certain that unregulated inquires and confused reflections of this kind only confronts the natural light and blind our mental powers.” But by themselves our mental capacities can lead us astray unless they are carefully regulated. This method therefore, consists, in those rules by which our capacities of intuition and deduction are guided in an orderly way.
By the mathematical method, Descartes meant going step by step, from what is clearly known for certain without any possibility of doubt to other truths that follow necessarily from the proceeding ones. His aim was to bring into philosophy the clarity and certainty of mathematics and to remove once and for all the uncertainties and disputes in philosophy.
As a rationalist, Descartes despised and distrusted the sense as means of acquiring truth and certain knowledge. The sense, in his view is deceptive and unreliable; reason is the reliable means of acquiring clear, distinct and certain knowledge. Hence, whatever the mind grasps by intuition is free from error, the illusions of the senses and is therefore true without any grounds to doubt. Hence, the basic operation of the mind in its search for truth is intuition that is clearly and distinctly apprehending reality by the light of reason.
Descartes was a great rationalist whose mind was most powerful and focused on how to bring man to the understanding of how to acquire knowledge that is certain. Of course it was his love for mathematics, and especially for geometry that influenced him to look for such a prior foundation in nature. In his attempt of how to bring man to the reality of true and reliable knowledge, he claimed that the only way that man can acquire certain knowledge is through his reasoning faculty, for him any knowledge that is not acquired through reasoning cannot be true because knowledge is not outside reasoning and cannot in any way go beyond it.
He totally rejects any knowledge that is said to be acquired through the senses because the senses for him do not hold water in the process of knowledge acquisition. He moved further to prove that if knowledge is said to be acquired through the sense then there can never be certainty in knowledge because the sense fro him are changeable and anything that cannot be reliable nor trusted neither can it be source of true knowledge. Descartes moved further to give some examples for his doubt of the certainty of the senses; for instance, take a wax of honey, taste it, then take the same honey wax and throw into a burning fire, after some few minutes remove it out and taste it again, you will find out that the taste, smell in fact even the structure will totally change to something else. With such examples, Descartes hold that since the senses are not certain and reliable then, they cannot be considered in the process of acquiring true knowledge.
He considered the heaven, the universe, colours, shapes, sand, and all other physical things to be nothing more than illusions and dreams. He moved further to give more examples by using himself and I quote, “I shall consider myself as having no hands, no eyes, no flesh, no blood, nor any sense; yet forcely believing myself to posses all these things.” If by this means, it is not in any power to arrive at the knowledge of any truth, I may at least do what is in my power, suspend judgment, and thus avoid belief in anything false, and avoid being imposed upon by these arch deceivers.
Descartes in rejecting the certainty about the physical world, uprooted all his accepted ideas, whether they reach him from authority, custom, or through the senses. He had left his mind free, not indeed blank, in the senses of John Locke, but free of all ideas that comes from the senses except those innate in the mind. Like Socrates, he had arrived at the point where he knew only that he did not know; and from here, he wanted to construct himself and the world a new. He claims to do this by pure reason.
In trying to prove the existence of God, he holds that God’s existence is self-evident and that his perfection can only be conceived. That again to understand the nature of God is like for example the understanding the nature of a triangle. It is evident that the sum of its three angles is two right angles. For him, the universe does not exist outside the mind. Once relation to the universe has become personal; by the process of doubt for him man explores himself. This is the thought which Descartes put into one of the famous sentences in philosophy, “Cogito ergo sum” ( I think, therefore I am) he describes reality as a dualism consisting two basic substance; Thought and Extension. His methods are mathematical method, intuitive and deductive method.
The mathematical method has to do with mental, intellectual or thinking. While the intuition is an intellectual activity that leaves no doubt in the mind. Then the deductive necessarily inference from facts that are known with certainty.

CONCLUSION
In the light of the above, there is no gain saying to doubt rational  fact that; according to Rene Descartes true and certain knowledge is not greatly influenced by sense experience. It is by owing to this fact that the interpretation of all things sensible or not are not the activities of the sense, but ideas or reason. In his argument about the existence of God, he proves the certainty of reason as a means of acquiring a true knowledge; being that God as an infinite being has no hands, body etc. physically, yet through reason we explain some of these basic truths.