Knowledge and Reality

Descartes' Meditations

René Descartes' Life

Descartes was born in La Haye , a small town in Touraine France in 1596. He was educated at a Jesuit school. But later said he learned little of substance there besides mathematics. He joined the army for a brief time during which he had dreams which he interpreted as a divine sign that he should found a unified science of nature based upon mathematics.

Descartes lived in Holland from 1628-1641. While there he wrote his first uncompleted book, which went unpublished until 1701, was the "Rules For The Direction of the Mind" in which he outlines his methodology for attaining knowledge. The method was based upon mathematics, but was intended for use in any inquiry. Methodology would dominate Descartes' thinking in much of his work.

He wrote a work in cosmology, Le Monde, but suppressed it when he heard of Gallieo 's condemnation by the church. He published work in French, not Latin, on mathematical and physical subjects where he offered mathematical treatments of terrestrial motions and from which we inherit analytic geometry.

He eventually left Holland in 1649 to join Queen Christina of Sweden as her tutor in philosophy. He died of pneumonia the next year. I've been told that the Queen required Descartes to lecture her in her freezing cold bedroom at six in the morning.

Knowledge and Reality

Descartes' Meditations

What is Descartes' Project?

"...I accepted many falsehoods as true in my youth, that what I built on the foundation of those falsehoods was dubious, and therefore, that once in my life, I would need to tear down everything and begin anew from the foundations if I wanted to establish any firm and lasting knowledge." (med. I p.112)

Some Preliminaries

Things that I will gloss-over

-Descartes wishes to define knowledge for ideas. Now his notion of ideas has our

notion of belief as a proper subset. I'll just talk about belief.

-Descartes wants to define knowledge for ideas and his definition of knowledge includes neither our notions of justification and belief, nor our notion of truth. However, he certainly thinks that one knows only things which are veridical.

Foundationalism about the structure of human beliefs:

The theory that all of your beliefs about the world are built upon/derived from a relatively small set of foundational beliefs. All of your beliefs, therefore, are either foundational or dependent upon foundational beliefs.

Foundationalist theories of knowledge:

The most common theory of knowledge is that knowledge is justified, true belief. Foundationalists traditionally hold that one's foundational beliefs are self- justifying, specifically, undoubtable and incorrigible by their very nature. They also hold that all non-foundational beliefs can only be justified (and hence known)
by deriving them from one's foundational beliefs in an appropriate manner.

Knowledge and Reality

Descartes' Meditations

What is Descartes' Project?

Some Premilinaries

How does Descartes begin his project?

Scepticism (also spelled Skepticism):

Scepticism is the thesis that someone or anyone does not have knowledge with regard to some area. For example, you may be sceptical of my knowledge of your family history. You may be sceptical of anyone's ability to know what your feeling or thinking. You may be sceptical of your own knowledge of how decisions are really made in Washington. A sceptical thesis has a particular scope (area of potential human belief). Descartes begins the Meditations by developing an external world scepticism. A thesis that he cannot know anything regarding the existence or nature of the external world. (Actually, even more he sometimes questions our ability to know mathematical truths, etc.)

Descartes' theory of justification:

"...I ought to withhold my assent just as carefully from what is not obviously certain and undoubtable as from what is obviously false, I can justify my rejection of my beliefs if I can find some ground for doubt in each." (Med p.112)

Knowledge and Reality

Descartes' Meditations

What is Descartes' Project?

Descartes seeks to first destroy his old "knowledge" structure by calling into question the justification of his most foundational beliefs. He will do this by trying to find reason to doubt each of them. Once he has destroyed everything that does not depend upon utter certainty, he will take only those beliefs which are utterly certain and rebuild his system of beliefs upon this strong foundation and in a way which will preserve the certainty of the foundational beliefs.

How does Descartes undermine his foundational beliefs about the external world?

All of my knowledge of the external world comes from my senses. If I can call my senses into question, if I can find reasons to doubt that they provide me with knowledge of the existence and nature of the external world, then I have reason to doubt all of those beliefs, and hence, they don't count as knowledge.

-The illusion argument:

-Generates doubt for only a some of my beliefs

-The dreaming argument:

-Dreams reflect the nature of reality, so I still have some knowledge

of the nature of the external world and that it exists.

-The evil demon argument:

-Destroys all certainty and undermines all of my beliefs about the

external world.

-Other versions of the evil demon argument:

-total recall

-brain in a vat

Knowledge and Reality

Descartes' Meditations

René Descartes' Life

What is Descartes' Project?

"...I accepted many falsehoods as true in my youth, that what I built on the foundation of those falsehoods was dubious, and therefore, that once in my life, I would need to tear down everything and begin anew from the foundations if I wanted to establish any firm and lasting knowledge." (med. I p.112)

Things that I will gloss-over

-Descartes wishes to define knowledge for ideas. Now his notion of ideas has our

notion of belief as a proper subset. I'll just talk about belief.

-Descartes wants to define knowledge for ideas and his definition of knowledge includes neither our notions of justification and belief, nor our notion of truth. However, he certainly thinks that one knows only things which are veridical.

Some Preliminaries

Foundationalism about the structure of human beliefs:

Some Premilinaries

Foundationalist theories of knowledge:

Knowledge = justified, true belief.

Foundational beliefs are self-justifying/undoubtable by their very nature.

Non-foundational beliefs can only be justified (and hence known) by deriving them from one's foundational beliefs in an appropriate manner.

Knowledge and Reality

Descartes' Meditations

What is Descartes' Project?

Some Premilinaries

How does Descartes begin his project?

Scepticism (also spelled Skepticism):

Descartes' theory of justification:

"...I ought to withhold my assent just as carefully from what is not obviously certain and undoubtable as from what is obviously false, I can justify my rejection of my beliefs if I can find some ground for doubt in each." (Med p.112)

Knowledge and Reality

Descartes' Meditations

What is Descartes' Project?

How does Descartes undermine his foundational beliefs about the external world?

-The illusion argument:

-Generates doubt for only a some of my beliefs

-The dreaming argument:

-Dreams reflect the nature of reality, so I still have some knowledge

of the nature of the external world and that it exists.

-The evil demon argument:

-Destroys all certainty and undermines all of my beliefs about the

external world.

-Other versions of the evil demon argument:

-total recall

-brain in a vat

Knowledge and Reality

Descartes' Meditations

Descartes' Cogito Ergo Sum

So we see that Descartes has found a sceptical hypothesis in meditation one which undermines all of his knowledge of the external world. In mediation two he further pursues his line of thought to determine if anything can withstand the sceptical hypothesis.

As Descartes aptly describes his vision of this project:

"Archimedes, in order that he might draw the terrestrial globe out of its place, and transport it elsewhere, demanded only that one point be fixed and immovable; in the same way I shall have the right to conceive high hopes if I am happy enough to discover one thing only which is certain and undoubtable." (p.194)

Descartes notices that his evil demon hypothesis requires that he exist:

"But there is a deceiver, supremely powerful and cunning, whose aim is to see

that I am always deceived. Then surely I exist, since I am deceived." (114)

So, Descartes realizes that his mental experiences, even if they are deceptive require that he exists. His very act of doubting establishes his existence, for how could he doubt if he did not exist? Here he has found his Archimedean point.

Knowledge and Reality

Descartes' Meditations

Descartes' Cogito Ergo Sum

So we that Descartes has found a sceptical hypothesis in meditation one which undermines all of his knowledge of the external world. In mediation two he further pursues his line of thought to determine if anything can withstand the sceptical hypothesis.

Descartes notices that his evil demon hypothesis requires that he exist:

"But there is a deceiver, supremely powerful and cunning, whose aim is to see

that I am always deceived. Then surely I exist, since I am deceived." (194)

So, Descartes realizes that his mental experiences, even if they are deceptive require that he exists. His very act of doubting establishes his existence, for how could he doubt if he did not exist?

Knowledge and Reality

Descartes' Meditations

I Exist, But What Am I, And How Do I Know I Exist?

Descartes has found his bedrock, that belief which presents itself in such a manner as to undoubtable. But, what does he know, what is he? And how does he know? He has no picture of himself? He formerly thought that all knowledge can through the senses, the pictures, smells etc. that filled his mind. How can it be that he knows that he exists when he hardly acknowledged the fact and has no perception of himself, and yet physical objects, those things that he has sensations of and that he thinks about always do not exist?

He can seem to know nothing of himself but that he exists as a thinking thing:

"But what then am I? A thinking thing. And what is that? Something that doubts, understands, affirms, denies, wills, refuses--and also imagines and senses." (195)

Descartes contemplates sensation, of a particular thing--a piece of wax.

He discovers that the wax remains identical even though it loses all of the properties it at first had. How can this be? How can he see, smell, touch that same piece of wax if it has none of its original properties?

Descartes concludes that it is the understanding that grasps the wax and not the senses which present pictures, smells, etc. all of which change:

"Thus I comprehend with my judgement, which is in my mind, objects that once

I believed myself to see with my eyes." (197)

So, Descartes concludes that

"I now know that physical objects are not really known through sensation or imagination, but are grasped by the understanding alone. And, from the fact that physical objects are grasped in virtue of their being understandable (rather than tangible or visible), I infer that I can't know anything more easily or plainly than my mind." (117)

Knowledge and Reality

Descartes' Meditations

Descartes' Cogito Ergo Sum

Descartes notices that his evil demon hypothesis requires that he exist:

"But there is a deceiver, supremely powerful and cunning, whose aim is to see

that I am always deceived. Then surely I exist, since I am deceived." (194)

So, Descartes realizes that his mental experiences, even if they are deceptive require that he exists. His very act of doubting establishes his existence, for how could he doubt if he did not exist?

Knowledge and Reality

Descartes' Meditations

I Exist, But What Am I, And How Do I Know I Exist?

He can seem to know nothing of himself but that he exists as a thinking thing:

"But what then am I? A thinking thing. And what is that? Something that doubts, understands, affirms, denies, wills, refuses--and also imagines and senses." (195)

Descartes concludes that it is the understanding that grasps the wax and not the senses which present pictures, smells, etc. all of which change:

"Thus I comprehend with my judgement, which is in my mind, objects that once

I believed myself to see with my eyes." (197)

So, Descartes concludes that

"I now know that physical objects are not really known through sensation or imagination, but are grasped by the understanding alone. And, from the fact that physical objects are grasped in virtue of their being understandable (rather than tangible or visible), I infer that I can't know anything more easily or plainly than my mind." (197)

Knowledge and Reality

Descartes' Meditations

Descartes' Notion of his Ideas

Descartes views his ideas as modifications of his own thought. He notices further that his ideas he formerly associated with the external world seem to come to him independent of his own will.

Descartes realizes that he does not know either the source of these ideas (they might come from himself or something external). He also does not know if the source is external, whether these internal modifications of his thought are veridical, i.e., "...have a similarity or conformity to things outside me." (199)

The Epistemological Problem

Descartes recognizes that his epistemological problem is one of whether or not these internal modifications of his thought (ideas) which he associates with sensation come from an external world and if so whether they provide him with any insight into the nature of this external source.

Knowledge and Reality

Descartes' Meditations

Descartes' Solution

In the remaining mediations , Descartes appeals to God, whose existence he establishes using a version of the ontological argument, as a guarantor of the veridicality of his perceptions. That is, God guarantees that his ideas accurately reflect the existence and nature of the external world.

A Snag, I have False Beliefs

Descartes realizes that God's existence seem to imply that there is no error. So, Descartes must show how error is possible.

"...error is a lack rather than a real thing dependant upon God. And I therefore understand that I can err without God's having given me the special ability to do so: I fall into error because my God-given ability to judge the truth isn't infinite." (124)

"I will surely attain the truth if I attend only to the things that I understand perfectly, distinguishing them from those that I grasp more obscurely and confusedly." (127)

Knowledge and Reality

Descartes' Meditations

Also: Material Objects

The essential nature of the mind is a nonspatial, thinking thing--a substance that exists in time and is a unity.

The essential nature of the body is an extended and unthinking substance that exists in time and has all of the properties of mathematics, i.e., of geometry and number (magnitude, shape, position, motion).

I have knowledge of only the general properties of material objects that I can grasp clearly and distinctly, like size, shape, etc. "But what about particular properties, such as the size and shape of the sun? ... These are open to doubt. But, since God is no deciever , and since I therefore have the God-given ability to correct any falsity that may be in my beliefs, I have high hopes of finding the truth about these things." (132)

Also in Meditation Seven

The body intimately interacts with the mind through the brain (particularly the pineal gland), though the two are distinct things.

The Cartesian Circle

-Future generations see the problem with Descartes' project, as executed, is that it is circular. To ascend from the pit of scepticism, he must find a means of introducing nonbasic beliefs. Descartes does this by proving the existence and benevolence of God and using God's existence and benevolence to allow him to accept those beliefs which he sees clearly and distinctly. However, to prove God's existence he relies upon the truth of the deliverances of the "natural light," i.e. he holds that what he perceives clearly and distinctly must be true. Specifically, he needs the principle, "...there must at least be as much reality in the efficient and total cause as in its effect." (p.200). But, nothing but God's existence and benevolence would guarantee the deliverances of the natural light.

Knowledge and Reality

Descartes' Meditations

Descartes' Notion of his Ideas

Descartes views his ideas as modifications of his own thought.

Descartes realizes that he does not know either the source of these ideas (they might come from himself or something external). He also does not know if the source is external, whether these internal modifications of his thought are veridical, i.e., "...have a similarity or conformity to things outside me." (119)

The Epistemological Problem

Descartes recognizes that his epistemological problem is one of whether or not these internal modifications of his thought (ideas) which he associates with sensation come from an external world and if so whether they provide him with any insight into the nature of this external source.

Knowledge and Reality

Descartes' Meditations

Descartes' Solution

In the remaining mediations , Descartes appeals to God, whose existence he establishes using a version of the ontological argument, as a guarantor of the veridicality of his perceptions. That is, God seems to guarantee that his ideas accurately reflect the existence and nature of the external world.

A Snag, I have False Beliefs

Descartes realizes that God's existence seem to imply that there is no error. So, Descartes must show how error is possible.

"...error is a lack rather than a real thing dependant upon God. And I therefore understand that I can err without God's having given me the special ability to do so: I fall into error because my God-given ability to judge the truth isn't infinite." (124)

"I will surely attain the truth if I attend only to the things that I understand perfectly, distinguishing them from those that I grasp more obscurely and confusedly." (127)

Knowledge and Reality

Descartes' Meditations

Also: Material Objects

The essential nature of the mind is a nonspatial, thinking thing--a substance that exists in time and is a unity.

The essential nature of the body is an extended and unthinking substance that exists in time and has all of the properties of mathematics, i.e., of geometry and number (magnitude, shape, position, motion).

"But what about particular properties, such as the size and shape of the sun? ... These are open to doubt. But, since God is no deciever , and since I therefore have the God-given ability to correct any falsity that may be in my beliefs, I have high hopes of finding the truth about these things." (132)

Also in Meditation Seven

The body intimately interacts with the mind through the brain (particularly the pineal gland), though the two are distinct things.

The Cartesian Circle

-The problem: Descartes' project, as executed, is circular.

-To prove God's existence he relies upon the truth of the deliverances of the "natural light," i.e. he holds that what he perceives clearly and distinctly must be true. Specifically, he needs the principle, "...there must at least be as much reality in the efficient and total cause as in its effect." (p.200).

-But, nothing but God's existence and benevolence would guarantee the deliverances of the natural light.