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\title {Descartes \\ Lecture 02}
 
\maketitle
 

Lecture 02:

Descartes

\def \ititle {Lecture 02}
\def \isubtitle {Descartes}
\begin{center}
{\Large
\textbf{\ititle}: \isubtitle
}
 
\iemail %
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\emph{Overall Topic}: What, according to Descartes, is the relation between a sensory perception and the thing perceived?

✓

?

How can we acquire knowledge about the essential nature of the bodies located outside us?

Sensory perceptions provide only very obscure information about the essential nature of bodies.

∴ Not by treating sensory perceptions as a basis for judgements about them.

This is all by way of a demonstration that Descartes was right. Sensory perceptions really do provide only very obscure information about the essential nature of bodies.
This is what we did last time ...
have argued that Descartes is right but not considered his reasons yet. [yyrama task is: Why did Descartes hold that sensory perceptions provide only very obscure information about the essential nature of bodies?]
 

The World: Light and Sound

 
\section{The World: Light and Sound}
 
\section{The World: Light and Sound}
\section{Against Resemblance}
Do sensory perceptions resemble their causes?

‘In putting forward an account of light, the first point I want to draw to your attention is that it is possible for there to be a difference between the sensation that we have of it, that is, the idea that we form of it in our imagination through the intermediary of our eyes, and what it is in the objects that produces the sensation in us, that is, what it is in the flame or in the Sun that we term ‘light’’

\citep[][p. 81 (AT XI:3)]{descartes:1998_world}

Descartes, The World (AT 3)

This quote is quite complex. Let's try to simplify. (Do this when quoting in your own work.)

The perceptual sensation of light is nothing like light itself.

Therefore, sensory perceptions provide only very obscure information about the essential nature of bodies.

Seems like a good argument to me.
But it’s not what Descartes wrote. Descartes’ argument is actually more subtle.

words

‘bear no resemblance to the things they signify’

‘yet they make us think of those things’

laughter & tears

bear no resemblance to joy or sadness

yet ‘make us read joy and sadness on faces’

sensations

‘why could nature not also have ’stablished some sign

which would make us have the sensation of light

even if the sign contained nothing in itself which is similar to the sensation?’

‘if words, which signify something only through human convention, are sufficient to make us think of things to which they bear no resemblance, why could not Nature also have established some sign which would make us have a sensation of light, even if that sign had in it nothing that resembled this sensation? And is it not thus that Nature has established laughter and tears, to make us read joy and sorrow on the face of men?’ \citep[][p.~81 (AT XI:4)]{descartes:1998_world}.

Words and expressions of emotion make us think of things which they do not resemble.

Therefore, sensory perceptions need not resemble the things they make us think of.

This argument seems closer to what Descartes had in mind.

How can we acquire knowledge about the essential nature of the bodies located outside us?

Each body has a form, which is its essential nature.

When a body is perceived, its form thereby enters the mind.

When a body is perceived, your sensory perception resembles the body’s form.

Thanks to this resemblance, your sensory perception acquaints you with the forms (essential natures) of bodies.

Which of these claim’s does Descartes claim about the proper purpose of sensory perceptions justify us in rejecting?
Has Descartes shown that this is incorrect? Not yet: he’s undermined the assumption that it *must* be correct. But why reject it?

a further argument

‘Do you think that, when we attend solely to the sound of words without attending to their signification, the idea of that sound which is formed in our thought is at all like the object that is the cause of it?

A man opens his mouth, moves his tongue, and breathes out:

I see nothing in all these actions which is in any way similar to the idea of the sound that they cause us to imagine.

And most philosophers maintain that sound is only a certain vibration of the air striking our ears.

Thus if the sense of hearing transmitted to our thought the true image of its object, then instead of making us think of the sound, it would have to make us think about the motion of the parts of the air that are vibrating against our ears.’

\citep[][p. 4--5 (AT IX:5)]{descartes:1998_world}
What do you think the argument here is? Reconstruct it!

Sound is only a certain vibration of the air striking our ears.

The sensory perception of sound is nothing like vibration of the air.

Therefore, sensory perceptions do not in general resemble their causes.

How can we acquire knowledge about the essential nature of the bodies located outside us?

Each body has a form, which is its essential nature.

When a body is perceived, its form thereby enters the mind.

When a body is perceived, your sensory perception resembles the body’s form.

Thanks to this resemblance, your sensory perception acquaints you with the forms (essential natures) of bodies.

Which of these claim’s does Descartes claim about the proper purpose of sensory perceptions justify us in rejecting?
Until now we didn’t see Descartes argue agains the view
But now we have a good argument

?

How can we acquire knowledge about the essential nature of the bodies located outside us?

Sensory perceptions provide only very obscure information about the essential nature of bodies.

∴ Not by treating sensory perceptions as a basis for judgements about them.

So now we have an argument for the claim that Sensory perceptions provide only very obscure information about the essential nature of bodies.

Method:

Identify a kind of sensory perception

Investigate the essential nature of its causes

Establish whether there is resemblance

Further illustration (not from The World). Descartes’ explanation of why the rainbow is a bow. Relevant because of the gap between sensory perception and the things which cause it. And shows Descartes examines sensory perceptions.

sensory perceptions
do not resemble
their causes

Descartes is more subtle in his argument In the intro to The World, he does not conclude that sensory perceptions do not resemble their causes. Instead ...

‘I have not brought up these examples to make you believe categorically that the light in the objects is something different from what it is in our eyes

I merely wanted you to suspect that there might be a difference’

\citep[][p.~82 (AT XI:6)]{descartes:1998_world}.

Descartes, The World (AT IX:6)

Compare Descartes’ strategy in The Meditations:

The usefulness of extensive doubt ‘lies in freeing us from our preconceived opinions, and providing the easiest route by which the mind may be led away from the senses.’

Meditations (Synopsis)

The World vs The Meditations

Why is the argument of The Meditations so different?

Descartes only thought of this argument later.

1629 begins work on The World

1633 Galileo condemned by the Church; abandons The World

1639 begins work on The Meditations; solicits approval of clergy

1641 publication of The Meditations

1663-1960 Descartes’ key works on the Index of Prohibited Works

The World vs The Meditations

Why is the argument of The Meditations so different?

Descartes only thought of this argument later.

The World was written before the Mediatations but never published.

Publishing The World would have got Descartes banned.

(as he eventually was anyway).
In writing philosophy, and in particular in writing the meditations, he had a very specific purpose: ‘In order to make his physics acceptable he had either to revise it in a way that would conciliate the Church, or to disguise its consequences, or to erect the whole doctrine on principles that not even the most hidebound of his religious critics could object to. Eventually, in the Meditations and the Principles of Philosophy, he adopted the third of these approaches’ (Sorell 2001, p. 36)
Actually what was Descartes’ argument in the Mediatations?
 

Doubt

 
\section{Doubt}
 
\section{Doubt}

?

How can we acquire knowledge about the essential nature of the bodies located outside us?

Sensory perceptions provide only very obscure information about the essential nature of bodies.

∴ Not by treating sensory perceptions as a basis for judgements about them.

We saw how in The World Descartes gives an argument for considering the claim that Sensory perceptions provide only very obscure information about the essential nature of bodies.
How does the argument go in The Meditations? [This is the task for next week’s seminars]

That we have grounds to doubt something

doesn’t imply we know it is false ...

So what can we conclude if we discover that we have reason to doubt something?

... but only that we have reason to withhold assent.

Argument ideas from Meditation 1

The senses sometimes deceive us

My brain may be ‘damaged by the persistent vapours of melancholia’

The dream argument

The deceiving God hypothesis

Cosmic deception

‘I see plainly that there are never any sure signs by means of which being awake can be distinguished from being asleep’

Meditation 1

‘... the principal reason for doubt, namely my inability to distinguish between being asleep and being awake. For ... there is a vast difference between the two, in that dreams are never linked by memory with all the other actions of life

‘when I distinctly see where things come from and where and when they come to me, and when I can connect my perceptions of them with the whole of the rest of my life without a break, then I am quite certain that when I encounter these things I am not asleep but awake.’

Meditation 6

\subsection{Dreaming} ‘I see plainly that there are never any sure signs by means of which being awake can be distinguished from being asleep’ (Meditation I)
‘... the principal reason for doubt, namely my inability to distinguish between being asleep and being awake. For ... there is a vast difference between the two, in that dreams are never linked by memory with all the other actions of life’ (Meditation 6)
‘when I distinctly see where things come from and where and when they come to me, and when I can connect my perceptions of them with the whole of the rest of my life without a break, then I am quite certain that when I encounter these things I am not asleep but awake’ (Meditation 6).
Do any considerations about dreaming provide ‘reasons ... which give us possible grounds for doubt about all things, especially material things, so long as we have no foundation for the sciences other than those we have had up until now’?

‘reasons are provided which give us possible grounds for doubt about all things, especially material things, so long as we have no foundation for the sciences other than those we have had up until now’

Synopsis

What are these reasons?

What are these reasons?

Do any considerations about dreaming provide such reasons?

Argument ideas from Meditation 1

The senses sometimes deceive us

My brain may be ‘damaged by the persistent vapours of melancholia’

The dream argument

The deceiving God hypothesis

Cosmic deception

‘How do I know that he has not brought it about that there is no earth, no sky, no extended thing, no shape, no size, no place, while at the same time ensuring that all these things appear to me to exist just as they do now?

What is more, since I sometimes believe that others go astray in cases where they think they have the most perfect knowledge, may I not similarly go wrong every time I add two and three or count the sides of a square, or in some even simpler matter, if that is imaginable?’

Is this a reason to doubt all things?

\subsection{Cosmic deception} ‘How do I know that he has not brought it about that there is no earth, no sky, no extended thing, no shape, no size, no place, while at the same time ensuring that all these things appear to me to exist just as they do now? What is more, since I sometimes believe that others go astray in cases where they think they have the most perfect knowledge, may I not similarly go wrong every time I add two and three or count the sides of a square, or in some even simpler matter, if that is imaginable?’
Is this a reason to doubt all things?

You are not in a position to know that you aren’t cosmically deceived

You do know this: if you are drinking coffee, then you are not cosmically deceived

Suppose you knew you were drinking coffee.

Then you would be in a position to know you are not cosmically deceived

Therefore you couldn’t know you are drinking coffee

I think Descartes’ idea is that this first claim is true insofar as you rely only on the senses.

?

How can we acquire knowledge about the essential nature of the bodies located outside us?

Sensory perceptions provide only very obscure information about the essential nature of bodies.

∴ Not by treating sensory perceptions as a basis for judgements about them.

How does this bear on our ultimate aim?
Perhaps this is a key idea ...

obscure -> does not enable you to know you aren’t cosmically deceived

not obscure (clear?) -> does enable you to know you aren’t cosmically deceived

For all your sensory perceptions reveal, you are not in a position to know that you aren’t cosmically deceived

Therefore, sensory perceptions provide only very obscure information about the essential nature of bodies.

How close do you think this is to Descartes’ argument in Meditation 1? Can you do better
In thinking about Descartes’ arguments in the first Meditation, it is important to remember what he is using doubt for. He does not want to establish that sensory perceptions actually deceive us. He only wants to show that they cannot be relied on to provide information about the essential nature of bodies.
Recall from our discussion of The World

‘I have not brought up these examples to make you believe categorically that the light in the objects is something different from what it is in our eyes

I merely wanted you to suspect that there might be a difference’

Descartes, The World (AT IX:6)

Compare Descartes’ strategy in The Meditations:

The usefulness of extensive doubt ‘lies in freeing us from our preconceived opinions, and providing the easiest route by which the mind may be led away from the senses.’

Meditations (Synopsis)

conclusion

In conclusion, ...
To conclude so far ...

?

How can we acquire knowledge about the essential nature of the bodies located outside us?

Sensory perceptions provide only very obscure information about the essential nature of bodies.

∴ Not by treating sensory perceptions as a basis for judgements about them.

Considered the search for arguments about this claim. First, it is true (representational momentum). Second, Descartes provides some good arguments for it in The World. Third, Descartes’ arguments in the First Meditation are harder to discern ... and that’s your job in writing a mini essay for your seminar. Good luck!!