In his writings Descartes is trying to achieve certainty, and that cannot be done with probable beliefs. So, he must use knowledge. He needs to find a safe starting point, a foundation. The way he establishes his foundation is through doubt. If a belief can be doubted then it is not certain and does not make a good foundation. He first considered authorities such as parents, teachers, priests, etc. but found that they are not good sources of absolute truth. The reason why is because those people have certain beliefs which can be based on nothing, and testimony of others can never provide certainty. Next, he considered the senses but again rejects this as a foundation because of the dream argument. The dream argument states that if I am dreaming, then my beliefs based on my sen

Descartes having proven that he, an immaterial substance exists considers the various ideas he finds within his consciousness and whether or not he could be the cause of them. An idea is any conscious mental state. He finds that he possesses the idea of a perfect being. A perfect being has all perfectible qualities to an infinite extent. The way he goes on proving god exists is that if Descartes, an imperfect being, who makes mistakes, has an idea of a perfect being the being must exist. The way he explains this is ideas are effects, so every idea has a cause, and all events have a cause. The cause of an idea must be at least as real and perfect as what the idea is about. So, the cause of my idea of a perfect being can’t be less real or perfect then what my idea is about. This means I am not the cause of this idea, since I am not perfect and I have doubts.

Descartes is a strong dualist. He believes a mind can exist without a body but a body can’t exist without a mind. What farther helps him in reinforcing his belief is that it is historically respected in the Christian religion that there is an afterlife and a resurrection. When a person goes to heaven the body stays behind and the soul or the mind goes on. Materialism is the belief that the only things that exist and are real are things which have physical properties and bodies. This is a weak theory because if only material things exist then minds do not exist.

At this point, Descartes feels he cannot be sure of anything but he is mistaken. He considers this, I necessarily exist. This statement is definitely true said or thought because it is self-evident. The I stands for an immaterial substance. I cannot doubt that I exist but I can doubt that I have a body. Substances or things have properties which can only exist if they are attached to something. Substances can be either physical or non-physical, and properties are essential or non-essential. The essential property of self, a non-essential substance is self-consciousness. An essential property of a thing is the properties such as if you remove it or them you destroy the thing. So, all Descartes is sure of right now is that he exists, he is not sure if anything in the external world exists.

Some topics in this essay:
, Math God, God Mind, external world, cause idea, ideas matter, idea perfect, self-evident ideas, essential property, external ideas, science religion, external world exists, beliefs based, dream argument, real perfect idea, cause idea perfect,