The World: Light and Sound

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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’

‘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?

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