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Do the Senses Deceive?

Sensory perceptions of tastes, smells, sounds, heat, cold, light, colors and the like ‘do not represent anything located outside our thought’

Principles

(\citealp[p.~ 219, AT VIII:35]{descartes:1985_csm1} cited by \citealp[p.~348]{simmons:1999_are})

‘from time to time I have found that the senses deceive’

\citep[p.~17, AT VII:18]{descartes:1985_csm2}

Meditation 1

How to resolve the puzzle?

‘when I see a stick, it [is] simply that rays of light are reflected off the stick and set up certain movements in the optic nerve and, via the optic nerve, in the brain

This movement in the brain ... is the first grade of sensory response.

the second grade ... extends to the mere perception of the colour and light reflected from the stick [...]

Nothing more than this should be referred to the sensory faculty, if we wish to distinguish it carefully from the intellect.

But suppose that ... I make a rational calculation about the ... shape ... of the stick:

although such reasoning is commonly assigned to the senses (which is why I have here referred it to the third grade of sensory response), it ... depends solely on the intellect.

Sixth Replies

Sensory perceptions of tastes, smells, sounds, heat, cold, light, colors and the like ‘do not represent anything located outside our thought’

Principles

(\citealp[p.~ 219, AT VIII:35]{descartes:1985_csm1} cited by \citealp[p.~348]{simmons:1999_are})

‘from time to time I have found that the senses deceive’

\citep[p.~17, AT VII:18]{descartes:1985_csm2}

Meditation 1

How to resolve the puzzle? Descartes is talking in the ordinary way, where such reasoning is ‘commonly assigned to the senses’ He doesn’t really mean it.

Or?

Always consider objections to your views!
In the Sixth Meditation, Descates returns to the topic and appears to say that the sense do deceive.
‘there may be some occurrence, not in the foot but in one of the other areas through which the nerves travel in their route from the foot to the brain, or even in the brain itself; and if this cause produces the same motion which is generally produced by injury to the foot, then pain will be felt as if it were in the foot. This deception of the senses is natural’ \citep[p.~61, AT VII:88]{descartes:1985_csm2}.

‘there may be some occurrence, not in the foot but in one of the other areas through which the nerves travel in their route from the foot to the brain, or even in the brain itself;

and if this cause produces the same motion which is generally produced by injury to the foot, then pain will be felt as if it were in the foot.

This deception of the senses is natural’

Sixth Meditation

Can we explain this away using the same strategy (ie its the third grade of sensory response)?

On Descartes’ view, can the senses deceive?

Sensory perceptions of tastes, smells, sounds, heat, cold, light, colors and the like ‘do not represent anything located outside our thought’

Principles

(\citealp[p.~ 219, AT VIII:35]{descartes:1985_csm1} cited by \citealp[p.~348]{simmons:1999_are})

‘from time to time I have found that the senses deceive’

\citep[p.~17, AT VII:18]{descartes:1985_csm2}

Meditation 1

‘pain will be felt as if it were in the foot [...] This deception of the senses is natural’

Meditation 6

How to resolve the puzzle?