This page is a brief and basic introduction to a few summary points about Rene' Descartes' life and philosophy. It is no substitute for an original source by the philosopher or a more in-depth analysis by experts in his work.

Most of what follows was derived from the Cottingham, Stoothoff, and Murdoch work, The Philosophical Writings of Descartes, known as the CSM volumes, 1984, vols. 1–3. Cambridge: Cambridge University Press. Other items are summarized from the Stanford Encyclopedia's entry on Descartes (http://plato.stanford.edu/entries/descartes-works/).

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René Descartes- (1596-1650) French philosopher and mathematician. Descartes was born in a small town near Tours that is now named for him. At the age of ten, he was sent to Jesuit college by his maternal grandmother (his mother had died soon after his birth).

He remained a boarding pupil for nine years and studied history, classics, and rhetoric in combination with natural philosophy. At the age of twenty-two, Descartes set out on a trek across Europe to find answers and knowledge.

After coming to a number of realizations, Descartes began publishing in mathematics and many of the sciences. In 1641 he published "Meditations on First Philosophy" which is considered to be his masterpiece. A few years afterwards, "Principles of Philosophy" became his ordered style and refined version of the meditations. It was written to be a university textbook.

After reluctantly accepting an invitation to tutor Queen Christina of Sweden, Descartes died of pnemonia due to the odd schedule he was forced to keep at the royal palace.

He was required to tutor the Queen at five o'clock in the morning, breaking from his habit of sleeping in during the morning. He is famous for his development of the Cartesian system, including Cartesian Doubt. He is best known for his "Cogito Ergo Sum" statement in relation to existence. "I think therefore I am"

Cogito Ergo Sum, "I think, therefore I am"

This statement seems to be redundant in the sense that saying the first person word "I" means, at some level, "I am". Before one can think, one must "be", in the sense of existence. So, why did Descartes not jump ahead to the conclusion of this statement and exert, "I am" rather than utilize the antecedent of an inferential statement like, "I think, therefore I am"? Was Descartes trying to emphasize the "thinking" part of the statement? Or is it all much simpler?

It’s unclear. By saying "I" one is thinking, but this is evident introspectively and immediately. Does this mean that one is necessarily existing? Well, we must first consider the nature of existence.

Can something not exist? Existence, I would assert, is a false notion that stems from the human condition. I exist. When will I not exist? Will I not exist when I die? In a sense, existence means the condition at the moment of introspection. "I exist- now, like this."

But, when I die, I will not be able to say that I exist. However, the ‘stuff’ that I’m made up of will still be around (or will it?). Therefore, existence seems to be only the capability to assert symbolically (mentally, verbally, etc...) that one is existing.

A tree can not assert that it exists, because it lacks any mental capacity. But, in the same light, do we really have any more mental capacity to exert our own existence than the tree? (This sounds strange...but has some interesting implications).

Introspection is something that we should be cautious of. It shows us amazing things, wonderful images, and poses questions that we may never be able to answer.

Why? I believe that the problem lies in the nature of introspection. When we look inward, we can see only those things that our minds produce, we certainly can not observe the workings of our minds- if we could there would be little need for philosophy.

These are merely 'surface' understandings of Descartes, short and direct.

    1. Doubt and Perception
    2. Knowledge, Judgement, Substance, and Attributes
    3. The Nature of Body, Space, Matter, and the Vacuum

For more on doubt, perception, and knowledge read my more extensive and in-depth essay: Breaking the Cartesian Circle.

1. DOUBT AND PERCEPTION:
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Descartes recommends doubt because it is the only way to free ourselves from the preconceived notions and assumptions that we have acquired since birth. This is the only way we can find the truth.

One reason why Descartes thinks we should doubt the evidence of our senses is because he knows that the senses can be in error. Madmen often see their physical reality differently than a sane man would see it, therefore their senses may be deceiving them.

A second reason for doubting one’s senses according to Descartes is because it is difficult to tell physical reality from the reality of a dream. Therefore, it may be that we are imagining everything in our physical world.

Descartes is unable to doubt that he is thinking. He knows that in any case, he is thinking about the reality around him, whether it be true or false. This leads him to conclude that he exists, because he is thinking.

Descartes conclusion about the ball of wax is that we judge what something is by thinking about it. Just as he assumes the figures outside his window are walking people, not automatons, he assumes the object before him is a ball of wax.

"Descartes", graphic drawing by Anthony Peter Iannini

L1. The ‘malicious demon’ plays an important role at the end of the First Meditation by Descartes. The demon is something which Descartes invents in order to contrast the conventional notion of god, because god is supposed to be ultimately good and would not deceive humans. Therefore, Descartes needs some entity that would have the power of god, but would be malicious towards humans. The creation of the ‘malicious demon’ serves to reinforce the doubt of his faculties, of his physical senses, and his mental ability to perceive the world around him. It is possible, he thinks, that the physical world, the earth, his body, the sky, the air, everything is merely an illusion. Descartes use of this evil figure serves to give possible validity to his doubts. Without the demon, or a similar deceptive entity, Descartes may not have reached such a strong motive or reason to question his senses. While the entity is fictitious, it is an extremely important part of the progression of Descartes’ thought and leads him to confirm his doubts when he is in danger of slipping back into acceptance of the world around him. The one remaining notion that Descartes is able to hold on to in his world of deception and falsities, is that he is thinking. In his mind, he thinks, therefore he exists.

In the 5th and 6th Objections and Replies, Descartes is defending his idea that we can only be sure of our existence through our knowing that we think. These are the only things that we can know absolutely.

Each of the objections brings forth a contradiction to what Descartes has found through his various Meditations. The 5th Objection is opposed to Descartes’ belief that thinking is the basis for existence because, in the view of the author, anything that acts, or is in motion, qualifies as existing.

The 5th reply meets the opposition by arguing that motion, or action, does not meet the qualifications for existence. Descartes states that he may not make the statement, "I am walking, therefore I exist…" Instead, the awareness of walking, not the walking itself, is the criteria for existence. Descartes uses the familiar example of walking in a dream, where one is actually asleep, but perceives walking. Therefore, it is once again thought that is absolute.

The 6th Objection raises a much stronger point in opposition to Descartes. The author believes that one can not know that one is actually thinking because thought itself is not understood.

Until the nature of thought is uncovered, then thinking, and existence is still in question. Therefore, even thought comes into the realm of doubt, and is not the ultimate proof of existence. Descartes meets this opposition by saying that such knowledge of thought is not required, and that such a knowledge of anything is impossible because it is a paradox (ad infinitum). Descartes resorts to talking about "internal awareness" as the criteria for knowing of thought.

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[1] First Meditation, para. 13
[2] Fifth Objections | CSM II 180
[3] Fifth Replies | CSM II 244
[4] Sixth Replies | CSM II 285

2. KNOWLEDGE, JUDGEMENT, SUBSTANCE, and ATTRIBUTES:
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Descartes thinks that, before we can extend our knowledge beyond the certainty that we exist, we must know God.

So that we do not make false judgements, Descartes thinks that we should never extend our will beyond the scope of our intellect. This is because the will is infinite, whereas the intellect is confined to finite perception.

Descartes mentions three different kinds of substance. The first substance is mind, the substance in which thought resides. The second substance is body, the substance of shape and position. The third substance is God, the substance of ultimate perfection.

Descartes thinks that each substance has a principle attribute and many (perhaps innumerable) regular attributes.

The principle attribute is the attribute that constitutes the essence and nature of the substance in question. For example, Descartes states that the principle attribute of mind is thought, and the principle attribute of body is extension.

According to Descartes, God never deceives us, yet we still make errors. Initially, Descartes explains that it is the nature of a created intellect to be finite. Because we are created by God, and we are finite, then the scope of our intellect does not cover everything.

And, because the will has a broader scope than intellect, we are able to make false judgements. No one, says Descartes, wants to go wrong.

Rather, we go wrong when we assert our will over that which we do not actually know. In this way, people often pass judgement on things that they lack perception of. However, Descartes goes into more detail about how we are not to blame God for our errors. If it is the case that we do make a false judgement, it is because there is fault in the way we act, or in the way we have used our freedom of will. God, according to Descartes, created our nature, which includes our free will, or ability to choose. Therefore, we are to blame when we do not sufficiently perceive something using what God has given us to perceive with. Also, we are not to blame God for keeping us from possessing and intellect that would be able to always discern truths from falsehoods because we have no right to do so. Descartes does address the thought that God could have prevented us from ever going wrong by stating that the power men were given was given such that we should be able to discourage others from evil. Descartes ends his defense of God with praise and thanks, and asks that we not complain about possible attributes of intellect that could have been given to us.

"Oxford Camera", 2007, by Anthony Peter Iannini

Descartes gives an account of a substance in Principles Pt. 1 section 51 that defines and differentiates the term ‘substance’. He states that a substance is that which can exist completely independently of anything else. And, because God created all creatures and all substances, God is the only substance which can exist without the existence of other substances.

When Descartes says that ‘substance’ is a term that does not apply univocally to God and his creatures, he means that God is the one true substance, and all other substances derive from God. Therefore, Descartes is distinguishing between a primary substance, God, and other substances that can not exist without the existence.

The NATURE OF BODY, SPACE, MATTER, and the VACUUM:
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According to Descartes, the nature of body consists in extension. That is, matter or body in general, affects the senses (such as weight, hardness or color), and is extended in length, breadth and depth.

Descartes does not think there is a difference between space and corporeal substance, yet he does think there is a difference in the way we conceive space and corporeal substance.

Like matter, space must have length, breadth and depth. Therefore, they are the same. However, when we move something like a stone, the space remaining seems (deceptively) to be empty. But, because matter, like space, has length, breadth and depth, the space remaining where the stone was is the same (in its extension) as when the stone was there.

A vacuum is space in which there is nothing whatsoever. Descartes does not believe that a vacuum exists, because it contradicts the idea that space and matter are the same. The existence of a vacuum would constitute a space with no length, breadth and depth. And the definition of space and matter is that which has extension or length, breadth and depth.

Descartes argues that if a vacuum existed between two bodies (the sides of a container), then the two bodies would have no space between them, and would be in contact.

According to Descartes, the diversity of matter depends on motion. He states that matter in the universe is all the same, and our perception of that matter depends on the mobility of its parts. Motion causes all material or corporeal things to take on the characteristics that we perceive them to have.

Descartes thinks that we are justified in believing in the existence of material things because, firstly, our sensations come from something other than our mind. He states that it is not in our power to give ourselves sensation, but that sensation is dependent on something that is acting on our senses. According to Descartes, we have sensory awareness of, or clear and distinct perception of, some form of matter that has length, breadth and depth.

This matter, because of its differently shaped and variously moving parts, gives us our sensations of color, smell, and pain. He addresses the question of whether or not God creates this extended matter in our minds, or if God causes the idea of something extended that actually lacks extension, by returning to the conclusion that God does not deceive us.

If it were the case that the extension of matter was put in our minds by God, then he would be deceiving us.

And, because God does not deceive us, then we must conclude that there is something that is extended in length, breadth and depth that is different from our minds and from God. Therefore, we are justified in believing in the existence of this substance that Descartes calls ‘body’ or ‘matter’.

Descartes thinks that the properties we normally attribute to bodies are not really in them. The properties that he has in mind are those that our senses perceive, such as shape, size, smell, hardness, weight, and other such properties.

We should explain these properties in terms of their motion and how that motion affects our senses. Descartes believes that we perceive differently from the matter itself. An example he gives is that of a sword cutting into the body.

While the sword and body contain separate properties, the ensuing pain is unlike either of them. This is our sense perception interpreting the movement and contact of matter. Like this, Descartes thinks that color, hardness, shape and other "dispositions in those objects" are all interpretations by our senses of the movement and contact of matter. Another example is the property of hardness.

An object is hard because of the perception of hardness, yet if the object moves away from us at the same rate we press upon it, then we perceive no hardness.

If it were the case that hardness were the nature of matter, then the matter in question would loose its nature. Therefore, the only true nature of matter is extension- because all of the qualities that our senses attribute to bodies can be removed from those bodies and the true nature of the bodies will remain the same. That is, they will still have extension, or length, breadth and depth.

[1] Principles of Philosophy: Pt. 2 sec. 4
[2] PP: Pt. 2 sec. 1
[3] PP: Pt. 4 sec. 197
[4] PP: Pt. 4 sec. 198
[5] PP: Pt. 2 sec. 4