HUMA1010 Lecture Notes - Lecture 9: Mind, Ontological Argument, Mental Substance
28 May 2018
School
Department
Course
Professor
Some background
Descartes (1596-1650)
•
French thinker, important in both mathematics and philosophy.
•
An important figure in the transition from medieval to modern thinking.
•
Sometimes described as the father of modern philosophy.
•
Perhaps more than anyone else, Descartes was responsible for making
epistemology the centre of philosophy.
•
He is famous for posing skeptical questions; but in order to establish certain
truths e.g. ‘I think, therefore I am’
•
This first truth is the basis for a system of certain knowledge
•
His most famous work, Meditations (1641), sets out the path we must follow
to attain knowledge of the world.
•
Descartes was a rationalist. Rationalism can be contrasted with empiricism.
•
Empiricism: all knowledge comes from experience.
•
Rationalism: some knowledge comes from pure reason.
•
Descartes wants to do is use reason to put knowledge on a firm foundation.
•
The Meditations
Descartes’ Meditations consists of 6 sections or ‘meditations’
•
Meditations 1 and 2 deal with systematic doubt and establishing the
certainty of one’s own existence
•
Meditations 3 and 5 involve arguments concerning the existence of God, and
Descartes’ account of the existence of the external world is in Meditation 6.
•
General approach
Descartes’ aim is to put his knowledge of the world on a firm footing
•
We can’t first have knowledge of the world and then look at what justifies us
having this knowledge.
•
For Descartes we have to first establish the foundations of knowledge, and
then go on to develop it. Hence, these are meditations on ‘first philosophy’.
•
Meditation 1
Descartes wants to use sceptical questioning to critically examine his
existing beliefs.
•
He aims to reject every belief there is the slightest reason for doubting, to
isolate beliefs that can’t be called into question. These will be a foundation
on which to build a new system of knowledge.
•
The basis of all his former beliefs is ‘sense experience’. Descartes aims to
show that we can’t be certain of any beliefs we acquire through the senses.
•
There are 3 stages in Descartes’ overall argument in the first Meditation:
1. the argument from sense-deception
•
2. the dream argument
•
3. the deceiving God or evil demon argument.
•
1. ARGUMENT FROM ILLUSION
Our senses sometimes deceive us (illusions, hallucinations etc)
•
We might be deceived with respect to objects that are very small or in the
distance, but how can we doubt what our senses tell us about our immediate
surroundings?
•
2. DREAM ARGUMENT
But: what if I am in fact asleep and dreaming rather than awake?
•
There is no certain way of distinguishing between dreaming and waking
experience.
•
the possibility that I might be dreaming makes it possible for me to doubt
even the most obvious and seemingly certain sense-based beliefs about the
world.
•
3. EVIL DEMON ARGUMENT
The upshot of these arguments is that the input of the senses cannot
function as the absolutely firm foundation Descartes is looking for.
•
what about mathematical truths? Could simple truths of mathematics
function as the absolutely firm foundation? E.g. 2 + 3 = 5.
•
But: couldn’t an all-powerful God make me go wrong even in mathematics
and geometry?
•
A good God would not deceive us – but an evil demon could.
•
The evil demon hypothesis is enough to destroy all Descartes’ former beliefs
about the world. There may be no external world at all.
•
Conclusion: Descartes cannot be certain of any of the beliefs about the world
which he has acquired through the senses; or even about basic
mathematical truths.
•
Meditation 2
In Meditation 2, Descartes establishes
1. that there is at least one thing I cannot call into question, that I exist.
2. what this self is
1. I EXIST
If I doubt, I must exist as the one who does the doubting.
•
In other words, if I am doubting/thinking, then I must exist – in order to do the
thinking.
•
Hence: I think therefore I am
•
This is the ‘cogito’ argument (‘cogito is Latin for ‘I think’)
•
2. WHAT THEN AM I?
The only personal characteristic that resists the evil demon hypothesis is my
thinking.
•
Conclusion: I am essentially a thing that thinks, a thinking thing.
•
That is, I am a substance whose essence is thinking, an intellectual or
mental substance.
•
In his ‘cogito’ argument, Descartes has only established the existence of his
mind, not his body (or brain).
•
When Descartes eventually re-establishes the existence of the material
world and his body (in Meditation 6), he will also draw a sharp distinction
between himself as a mind or thinking substance, and his body.
•
This is Descartes’ ‘dualistic’ picture of the human being, as a combination of
mind and body, thinking substance and ‘extended substance’.
•
So at this point Descartes can be certain that he exists, and that he is a
mind, a thinking substance.
•
He can also be certain of the contents of this mind, certain that he has
certain thoughts or ideas
•
These ideas include his perceptions (though there may be no external object
corresponding to those perceptions).
•
He can also be certain of seemingly self-evident truths, things that can be
seen to be true just by inspecting the ideas involved e.g. a triangle has 3
sides. Nowadays we would call these ‘conceptual truths’
•
In Descartes’ terms, when we have a ‘clear and distinct’ perception of
something, there is no doubt about it. Whatever we perceive ‘clearly and
distinctly’ is true.
•
Descartes is referring here to a mental, purely intellectual, kind of perception
(the ‘natural light’).
•
Meditation 3
1. FIRST ARGUMENT
Amongst his ideas, Descartes finds the idea of a God. He aims to show that
he could not have this idea unless there is a real God to produce it in him.
•
He introduces a causal principle: ‘there must be at least as much reality in
the cause as in the effect of the cause’. This is supposedly manifest by the
‘natural light’.
•
2. ARGUMENT FOR THE EXISTENCE OF GOD
The task now for Descartes is to regain his certainty in the existence of the
external world.
To do this, Descartes thinks he has to establish the existence of a non-
deceiving God.
He has 2 arguments for the existence of God
This causal principle applied to ideas =
Ideas have a representational content. If an idea represents some object
with a certain characteristic, this characteristic is present representatively in
my idea.
The argument:
1. I have an idea of God as a supreme being who is eternal, infinite,
omniscient, omnipotent, perfect in every way.
2. this idea has to be caused or produced by something.
3. the cause of this idea must be something that actually has all the
properties to be found merely representatively in my idea (being eternal,
infinite, omniscient, omnipotent etc).
4. I cannot have produced the idea of God myself. The cause of this idea can
only be God himself.
5. Therefore, God exists.
Meditation 4
Descartes takes himself to have established the existence of god.
•
And God, as Descartes understands him, cannot be a deceiver. If God is
perfect, he is also morally perfect, and deceit is a moral imperfection
(Meditation 4).
•
So Descartes takes himself to have established the existence of a non-
deceiving god.
•
Meditation 5
1. WHAT IS A MATERIAL OBJECT?
A clear and distinct notion of material object is of something essentially
extended (has length, breadth and depth) – and capable of assuming an
infinite variety of shapes.
It is an extended substance.
2. SECOND ARGUMENT (Meditation 5):
1. God is defined as a supremely perfect being;
2. it is claimed that supreme perfection implies existence. A supremely
perfect being has all the perfections, and one of the perfections is
existence;
3. therefore God exists
Note: this is a version of the ontological argument
Meditations 5, 6
THE EXTERNAL WORLD
How does Descartes actually proceed to knowledge of the external world?
1.First, he arrives at a clear and distinct perception of what a material object
is (Meditation 5)
2. Then he argues that material things, as he conceives them, actually exist
(Meditation 6).
Meditation 6
2. ARGUMENT FOR EXISTENCE OF MATERIAL OBJECTS
Descartes knows that material things are capable of existing, at least as he
clearly and distinctly conceives them (i.e. as extended substance).
-
He formerly believed that his sense perceptions came from material objects
outside him, because they appear without his consent, and were more vivid
than what he could visualise.
-
In Meditation 1, systematic doubt including evil demon hypothesis called his
senses into question. But now he has established the existence of a non-
deceiving god.
-
He also proceeds to argue that, if he is nothing but a thinking thing, he
cannot be producing the sense perceptions.
-
So the sense perceptions must derive from something other than himself:
either from God or material objects.
-
It’s not God, because God is not a deceiver, and has given him a strong
inclination to believe sense perceptions are produced by material objects.
God would be a deceiver if the sense perceptions came from a source other
than that.
-
Therefore material things exist.-
So on the basis that God exists and is not a deceiver, Descartes is arguing
that the things we seem to see do in fact exist. The input of our senses is
mostly reliable.
-
So, Descartes ends up with a philosophical justification for saying that the
senses are a source of knowledge. Our sense impressions are produced by
material objects, understood as extended substance.
-
Comments
Two comments about this:
Firstly, Descartes is forced to rely almost entirely on God in demonstrating
the existence of the material world. God is the bridge from his mind to the
external world.
•
Descartes’ use of God to establish the existence of the external world is not
very convincing; nor are his arguments for the existence of God. The
religious bridge readily collapses.
•
If we accept the Cartesian starting point that all we have direct access to are
the contents of our own minds, we are left with the problem of whether any
knowledge of an external world is possible.
•
The Cartesian legacy is to set up the problem of knowledge in this way, and
it becomes a dominant issue in subsequent accounts of knowledge.
•
Secondly, Descartes thinks he has crossed the bridge from his mind to the
external world, and that knowledge of the external world is possible.
•
The things we seem to see do in fact exist. The input of our senses is mostly
reliable. So, Descartes ends up saying the senses are a source of
knowledge.
•
This is broadly what was argued by the empiricist practitioners of the new
natural sciences.
•
But there are two important differences between Descartes and the
practitioners of the new sciences
1. Descartes thinks that it is also possible to acquire knowledge of the world
through reason alone, without reference to experience
2. For the practitioners of the new sciences, the idea that the senses are a
source of knowledge is an assumption. For Descartes, it is the conclusion of
a long and involved argument
Week 9: Rene Descartes
Wednesday, 10 May 2017
9:19 am
Some background
Descartes (1596-1650)
•
French thinker, important in both mathematics and philosophy.
•
An important figure in the transition from medieval to modern thinking.
•
Sometimes described as the father of modern philosophy.
•
Perhaps more than anyone else, Descartes was responsible for making
epistemology the centre of philosophy.
•
He is famous for posing skeptical questions; but in order to establish certain
truths e.g. ‘I think, therefore I am’
•
This first truth is the basis for a system of certain knowledge
•
His most famous work, Meditations (1641), sets out the path we must follow
to attain knowledge of the world.
•
Descartes was a rationalist. Rationalism can be contrasted with empiricism.
•
Empiricism: all knowledge comes from experience.
•
Rationalism: some knowledge comes from pure reason.
•
Descartes wants to do is use reason to put knowledge on a firm foundation.
•
The Meditations
Descartes’ Meditations consists of 6 sections or ‘meditations’
•
Meditations 1 and 2 deal with systematic doubt and establishing the
certainty of one’s own existence
•
Meditations 3 and 5 involve arguments concerning the existence of God, and
Descartes’ account of the existence of the external world is in Meditation 6.
•
General approach
Descartes’ aim is to put his knowledge of the world on a firm footing
•
We can’t first have knowledge of the world and then look at what justifies us
having this knowledge.
•
For Descartes we have to first establish the foundations of knowledge, and
then go on to develop it. Hence, these are meditations on ‘first philosophy’.
•
Meditation 1
Descartes wants to use sceptical questioning to critically examine his
existing beliefs.
•
He aims to reject every belief there is the slightest reason for doubting, to
isolate beliefs that can’t be called into question. These will be a foundation
on which to build a new system of knowledge.
•
The basis of all his former beliefs is ‘sense experience’. Descartes aims to
show that we can’t be certain of any beliefs we acquire through the senses.
•
There are 3 stages in Descartes’ overall argument in the first Meditation:
1. the argument from sense-deception
•
2. the dream argument
•
3. the deceiving God or evil demon argument.
•
1. ARGUMENT FROM ILLUSION
Our senses sometimes deceive us (illusions, hallucinations etc)
•
We might be deceived with respect to objects that are very small or in the
distance, but how can we doubt what our senses tell us about our immediate
surroundings?
•
2. DREAM ARGUMENT
But: what if I am in fact asleep and dreaming rather than awake?
•
There is no certain way of distinguishing between dreaming and waking
experience.
•
the possibility that I might be dreaming makes it possible for me to doubt
even the most obvious and seemingly certain sense-based beliefs about the
world.
•
3. EVIL DEMON ARGUMENT
The upshot of these arguments is that the input of the senses cannot
function as the absolutely firm foundation Descartes is looking for.
•
what about mathematical truths? Could simple truths of mathematics
function as the absolutely firm foundation? E.g. 2 + 3 = 5.
•
But: couldn’t an all-powerful God make me go wrong even in mathematics
and geometry?
•
A good God would not deceive us – but an evil demon could.
•
The evil demon hypothesis is enough to destroy all Descartes’ former beliefs
about the world. There may be no external world at all.
•
Conclusion: Descartes cannot be certain of any of the beliefs about the world
which he has acquired through the senses; or even about basic
mathematical truths.
•
Meditation 2
In Meditation 2, Descartes establishes
1. that there is at least one thing I cannot call into question, that I exist.
2. what this self is
1. I EXIST
If I doubt, I must exist as the one who does the doubting.
•
In other words, if I am doubting/thinking, then I must exist – in order to do the
thinking.
•
Hence: I think therefore I am
•
This is the ‘cogito’ argument (‘cogito is Latin for ‘I think’)
•
2. WHAT THEN AM I?
The only personal characteristic that resists the evil demon hypothesis is my
thinking.
•
Conclusion: I am essentially a thing that thinks, a thinking thing.
•
That is, I am a substance whose essence is thinking, an intellectual or
mental substance.
•
In his ‘cogito’ argument, Descartes has only established the existence of his
mind, not his body (or brain).
•
When Descartes eventually re-establishes the existence of the material
world and his body (in Meditation 6), he will also draw a sharp distinction
between himself as a mind or thinking substance, and his body.
•
This is Descartes’ ‘dualistic’ picture of the human being, as a combination of
mind and body, thinking substance and ‘extended substance’.
•
So at this point Descartes can be certain that he exists, and that he is a
mind, a thinking substance.
•
He can also be certain of the contents of this mind, certain that he has
certain thoughts or ideas
•
These ideas include his perceptions (though there may be no external object
corresponding to those perceptions).
•
He can also be certain of seemingly self-evident truths, things that can be
seen to be true just by inspecting the ideas involved e.g. a triangle has 3
sides. Nowadays we would call these ‘conceptual truths’
•
In Descartes’ terms, when we have a ‘clear and distinct’ perception of
something, there is no doubt about it. Whatever we perceive ‘clearly and
distinctly’ is true.
•
Descartes is referring here to a mental, purely intellectual, kind of perception
(the ‘natural light’).
•
Meditation 3
1. FIRST ARGUMENT
Amongst his ideas, Descartes finds the idea of a God. He aims to show that
he could not have this idea unless there is a real God to produce it in him.
•
He introduces a causal principle: ‘there must be at least as much reality in
the cause as in the effect of the cause’. This is supposedly manifest by the
‘natural light’.
•
2. ARGUMENT FOR THE EXISTENCE OF GOD
The task now for Descartes is to regain his certainty in the existence of the
external world.
To do this, Descartes thinks he has to establish the existence of a non-
deceiving God.
He has 2 arguments for the existence of God
This causal principle applied to ideas =
Ideas have a representational content. If an idea represents some object
with a certain characteristic, this characteristic is present representatively in
my idea.
The argument:
1. I have an idea of God as a supreme being who is eternal, infinite,
omniscient, omnipotent, perfect in every way.
2. this idea has to be caused or produced by something.
3. the cause of this idea must be something that actually has all the
properties to be found merely representatively in my idea (being eternal,
infinite, omniscient, omnipotent etc).
4. I cannot have produced the idea of God myself. The cause of this idea can
only be God himself.
5. Therefore, God exists.
Meditation 4
Descartes takes himself to have established the existence of god.
•
And God, as Descartes understands him, cannot be a deceiver. If God is
perfect, he is also morally perfect, and deceit is a moral imperfection
(Meditation 4).
•
So Descartes takes himself to have established the existence of a non-
deceiving god.
•
Meditation 5
1. WHAT IS A MATERIAL OBJECT?
A clear and distinct notion of material object is of something essentially
extended (has length, breadth and depth) – and capable of assuming an
infinite variety of shapes.
It is an extended substance.
2. SECOND ARGUMENT (Meditation 5):
1. God is defined as a supremely perfect being;
2. it is claimed that supreme perfection implies existence. A supremely
perfect being has all the perfections, and one of the perfections is
existence;
3. therefore God exists
Note: this is a version of the ontological argument
Meditations 5, 6
THE EXTERNAL WORLD
How does Descartes actually proceed to knowledge of the external world?
1.First, he arrives at a clear and distinct perception of what a material object
is (Meditation 5)
2. Then he argues that material things, as he conceives them, actually exist
(Meditation 6).
Meditation 6
2. ARGUMENT FOR EXISTENCE OF MATERIAL OBJECTS
Descartes knows that material things are capable of existing, at least as he
clearly and distinctly conceives them (i.e. as extended substance).
-
He formerly believed that his sense perceptions came from material objects
outside him, because they appear without his consent, and were more vivid
than what he could visualise.
-
In Meditation 1, systematic doubt including evil demon hypothesis called his
senses into question. But now he has established the existence of a non-
deceiving god.
-
He also proceeds to argue that, if he is nothing but a thinking thing, he
cannot be producing the sense perceptions.
-
So the sense perceptions must derive from something other than himself:
either from God or material objects.
-
It’s not God, because God is not a deceiver, and has given him a strong
inclination to believe sense perceptions are produced by material objects.
God would be a deceiver if the sense perceptions came from a source other
than that.
-
Therefore material things exist.-
So on the basis that God exists and is not a deceiver, Descartes is arguing
that the things we seem to see do in fact exist. The input of our senses is
mostly reliable.
-
So, Descartes ends up with a philosophical justification for saying that the
senses are a source of knowledge. Our sense impressions are produced by
material objects, understood as extended substance.
-
Comments
Two comments about this:
Firstly, Descartes is forced to rely almost entirely on God in demonstrating
the existence of the material world. God is the bridge from his mind to the
external world.
•
Descartes’ use of God to establish the existence of the external world is not
very convincing; nor are his arguments for the existence of God. The
religious bridge readily collapses.
•
If we accept the Cartesian starting point that all we have direct access to are
the contents of our own minds, we are left with the problem of whether any
knowledge of an external world is possible.
•
The Cartesian legacy is to set up the problem of knowledge in this way, and
it becomes a dominant issue in subsequent accounts of knowledge.
•
Secondly, Descartes thinks he has crossed the bridge from his mind to the
external world, and that knowledge of the external world is possible.
•
The things we seem to see do in fact exist. The input of our senses is mostly
reliable. So, Descartes ends up saying the senses are a source of
knowledge.
•
This is broadly what was argued by the empiricist practitioners of the new
natural sciences.
•
But there are two important differences between Descartes and the
practitioners of the new sciences
1. Descartes thinks that it is also possible to acquire knowledge of the world
through reason alone, without reference to experience
2. For the practitioners of the new sciences, the idea that the senses are a
source of knowledge is an assumption. For Descartes, it is the conclusion of
a long and involved argument
Week 9: Rene Descartes
Wednesday, 10 May 2017 9:19 am
Document Summary
French thinker, important in both mathematics and philosophy. An important figure in the transition from medieval to modern thinking. Sometimes described as the father of modern philosophy. Perhaps more than anyone else, descartes was responsible for making epistemology the centre of philosophy. He is famous for posing skeptical questions; but in order to establish certain truths e. g. i think, therefore i am". This first truth is the basis for a system of certain knowledge. His most famous work, meditations (1641), sets out the path we must follow to attain knowledge of the world. Descartes wants to do is use reason to put knowledge on a firm foundation. Descartes" meditations consists of 6 sections or meditations". Meditations 1 and 2 deal with systematic doubt and establishing the certainty of one"s own existence. Meditations 3 and 5 involve arguments concerning the existence of god, and. Descartes" account of the existence of the external world is in meditation 6.
