DebateLabKIT/deepa2-corpus · Datasets at Hugging Face

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happens to inhabit.
Descartes applies the equivalent of Leibniz ’ Law – in particular, that half
of the equivalence that is the conditional principle now often referred to as
the “ indiscernibility of identicals ” – in a widely imitated general strategy
for demonstrating the nonidentity of two distinct things by arguing for a
difference in their properties. What is ahistorically called “ Leibniz ’ indiscernibility
of identicals principle ” holds that for any A and B, if A = B, then
A and B have all of their properties in common. Certainly Descartes would
not have known the principle by either of these names but takes it for
granted that distinctions between objects are drawn on the basis of a distinction
among their properties. Descartes has the same intuitive grasp of
the idea that identicals must have identical properties, and that any discrepancy
among the properties of distinctly designated objects implies that the
objects themselves are not identical. In order to prove that mind ≠ body in
Meditation 2, Descartes claims to have found a difference in the properties
of his mind and body, a property that his mind has but his body does not
have, or conversely.
Descartes singles out the property that he argues distinguishes his body
from his mind in two ways. He speaks of his mind as being “ better knowable
” or “ more easily knowable ” than his body and of his body as being
such that its existence can be rationally doubted under the assumptions of
a methodological skepticism while his mind is such that its existence cannot
be rationally doubted, since entertaining doubt is a conscious state and in
some cases an act of mind. The conclusion that Descartes can rationally
doubt the existence of his body but not of his mind is supported, in turn,
by Descartes ’ consideration that there might be an evil demon who systematically
deceives him concerning the reality of any of his sense impressions
that appear to reveal the existence and nature of an external world outside
of, but correctly representing, the contents of his thoughts (the evil demon
hypothesis). Descartes on pain of contradiction cannot consistently doubt
the existence of his mind, since the actual entertainment of doubt would
necessarily be an event actually occurring in and hence presupposing the
existence of his mind ( Cogito, sum , in Latin; or “ When I think [including
when I doubt], I exist ” ) (#35, #36).
Descartes motivates his discussion of mind – body nonidentity in
Meditation 2 by considering the sensible properties of a piece of wax that
he invites the reader to imagine him describing as he holds and observes it
in his hand. Descartes believes that the wax is better known to the intellect
than by the senses because when the sensible properties of the wax all
292 Dale Jacquette
undergo change as the wax is gradually introduced to the heat of a fl ame,
the senses alone do not tell us that it was the same wax that has undergone
changes to its shape, size, color, smell, and other empirically perceivable
properties. From this, Descartes draws the general conclusion that things
known by the mind, including the mind itself, are better knowable than
things, such as the body, known primarily or only with the aid of the senses.
Descartes ’ proposition that his body but not his mind has the property of
being such that its existence can be rationally doubted by his mind reinforces
the argument ’ s assumption that Descartes ’ mind is better knowable
than his body, in the sense that he must infer the existence of his body from
the evidence of the senses, while the existence of mind upon refl ection is
immediately known to itself and knows itself self - refl ectively and introspectively,
directly and without the intermediary of logical or inductive
inference.
Descartes ’ fi rst or Meditations 2 ’ s mind ≠ body argument has nevertheless
been criticized as subject to a fatal dilemma. The kind of property
Descartes maintains his mind has but his body does not have (better or
easier knowability) or that his body has but his mind does not have (such
that its existence is capable of being rationally doubted by his own mind)
seems to involve a mistaken, excessively general, application of what with
appropriate qualifi cations we shall continue to call “ Leibniz ’ principle of
the indiscernibility of identicals. ” Descartes ’ fi rst or Meditation 2 ’ s argument
for mind ≠ body depends on what is sometimes called a “ converse
intentional property, ” a property that belongs to an object by virtue of the
intentional attitude that a thinking subject adopts or might adopt toward
it. If I love Lisbon, then I have the intentional property of loving Lisbon,
and Lisbon has the converse intentional property of being loved by me. If
I doubt the existence of my body, then I have the intentional property of
doubting the existence of my body, and my body has the converse intentional
property of being such that its existence is doubted by me. Entities
are distinguished when they can be shown not to share all of their properties.
If it is a property of Lisbon that it is loved by me, and if I do not
equally love London, then, if converse intentional properties are included
among the shared properties of identical objects prescribed by Leibniz ’ Law,
it should follow in this case that Lisbon ≠ London. If I equally loved
London and Lisbon, then fortunately there would still remain many differences
between them by which their nonidentity could be established as a
consequence of Leibniz ’ Law. Lisbon and London have many things in
common despite being different cities, so why shouldn ’ t they have my equal
love for each of them in common?
Descartes ’ fi rst mind ≠ body (Meditation 2) argument makes a philosophically
more unfortunate use of converse intentional properties in applying
the indiscernibility of identicals principle. His argument is sometimes
Descartes’ Arguments for the Mind–Body Distinction 293
said to commit an “ intensional fallacy. ” The objection is that by defi nition
converse intentional properties do not belong intrinsically to objects but
only as a consequence of the extrinsic circumstance of being thought of
in a certain way by certain thinking subjects. Changes in object A ’ s and
object B ’ s converse intentional properties as a result would seem to leave
the object itself completely untouched as to the satisfaction or not of its
intrinsic identity conditions. We know that 1 + 1 = 2, for example, even
though someone might doubt that 1 + 1 is a prime number despite not
doubting that 2 is a prime number. We know that Mark Twain = Samuel
Clemens, regardless of whether or not someone happens to believe that
Mark Twain wrote Tom Sawyer while doubting that Samuel Clemens wrote
Tom Sawyer . Converse intentional properties invalidate Leibniz ’ Law as a
universal identity principle, which means that extrinsic converse intentional
properties should be barred from its applications. Unfortunately, Descartes ’
fi rst (Meditation 2) mind ≠ body argument commits precisely the “ intensional
fallacy ” of deducing the nonidentity of body and mind on the basis

happens to inhabit.

Descartes applies the equivalent of Leibniz ’ Law – in particular, that half

of the equivalence that is the conditional principle now often referred to as

the “ indiscernibility of identicals ” – in a widely imitated general strategy

for demonstrating the nonidentity of two distinct things by arguing for a

difference in their properties. What is ahistorically called “ Leibniz ’ indiscernibility

of identicals principle ” holds that for any A and B, if A = B, then

A and B have all of their properties in common. Certainly Descartes would

not have known the principle by either of these names but takes it for

granted that distinctions between objects are drawn on the basis of a distinction

among their properties. Descartes has the same intuitive grasp of

the idea that identicals must have identical properties, and that any discrepancy

among the properties of distinctly designated objects implies that the

objects themselves are not identical. In order to prove that mind ≠ body in

Meditation 2, Descartes claims to have found a difference in the properties

of his mind and body, a property that his mind has but his body does not

have, or conversely.

Descartes singles out the property that he argues distinguishes his body

from his mind in two ways. He speaks of his mind as being “ better knowable

” or “ more easily knowable ” than his body and of his body as being

such that its existence can be rationally doubted under the assumptions of

a methodological skepticism while his mind is such that its existence cannot

be rationally doubted, since entertaining doubt is a conscious state and in

some cases an act of mind. The conclusion that Descartes can rationally

doubt the existence of his body but not of his mind is supported, in turn,

by Descartes ’ consideration that there might be an evil demon who systematically

deceives him concerning the reality of any of his sense impressions

that appear to reveal the existence and nature of an external world outside

of, but correctly representing, the contents of his thoughts (the evil demon

hypothesis). Descartes on pain of contradiction cannot consistently doubt

the existence of his mind, since the actual entertainment of doubt would

necessarily be an event actually occurring in and hence presupposing the

existence of his mind ( Cogito, sum , in Latin; or “ When I think [including

when I doubt], I exist ” ) (#35, #36).

Descartes motivates his discussion of mind – body nonidentity in

Meditation 2 by considering the sensible properties of a piece of wax that

he invites the reader to imagine him describing as he holds and observes it

in his hand. Descartes believes that the wax is better known to the intellect

than by the senses because when the sensible properties of the wax all

292 Dale Jacquette

undergo change as the wax is gradually introduced to the heat of a fl ame,

the senses alone do not tell us that it was the same wax that has undergone

changes to its shape, size, color, smell, and other empirically perceivable

properties. From this, Descartes draws the general conclusion that things

known by the mind, including the mind itself, are better knowable than

things, such as the body, known primarily or only with the aid of the senses.

Descartes ’ proposition that his body but not his mind has the property of

being such that its existence can be rationally doubted by his mind reinforces

the argument ’ s assumption that Descartes ’ mind is better knowable

than his body, in the sense that he must infer the existence of his body from

the evidence of the senses, while the existence of mind upon refl ection is

immediately known to itself and knows itself self - refl ectively and introspectively,

directly and without the intermediary of logical or inductive

inference.

Descartes ’ fi rst or Meditations 2 ’ s mind ≠ body argument has nevertheless

been criticized as subject to a fatal dilemma. The kind of property

Descartes maintains his mind has but his body does not have (better or

easier knowability) or that his body has but his mind does not have (such

that its existence is capable of being rationally doubted by his own mind)

seems to involve a mistaken, excessively general, application of what with

appropriate qualifi cations we shall continue to call “ Leibniz ’ principle of

the indiscernibility of identicals. ” Descartes ’ fi rst or Meditation 2 ’ s argument

for mind ≠ body depends on what is sometimes called a “ converse

intentional property, ” a property that belongs to an object by virtue of the

intentional attitude that a thinking subject adopts or might adopt toward

it. If I love Lisbon, then I have the intentional property of loving Lisbon,

and Lisbon has the converse intentional property of being loved by me. If

I doubt the existence of my body, then I have the intentional property of

doubting the existence of my body, and my body has the converse intentional

property of being such that its existence is doubted by me. Entities

are distinguished when they can be shown not to share all of their properties.

If it is a property of Lisbon that it is loved by me, and if I do not

equally love London, then, if converse intentional properties are included

among the shared properties of identical objects prescribed by Leibniz ’ Law,

it should follow in this case that Lisbon ≠ London. If I equally loved

London and Lisbon, then fortunately there would still remain many differences

between them by which their nonidentity could be established as a

consequence of Leibniz ’ Law. Lisbon and London have many things in

common despite being different cities, so why shouldn ’ t they have my equal

love for each of them in common?

Descartes ’ fi rst mind ≠ body (Meditation 2) argument makes a philosophically

more unfortunate use of converse intentional properties in applying

the indiscernibility of identicals principle. His argument is sometimes

Descartes’ Arguments for the Mind–Body Distinction 293

said to commit an “ intensional fallacy. ” The objection is that by defi nition

converse intentional properties do not belong intrinsically to objects but

only as a consequence of the extrinsic circumstance of being thought of

in a certain way by certain thinking subjects. Changes in object A ’ s and

object B ’ s converse intentional properties as a result would seem to leave

the object itself completely untouched as to the satisfaction or not of its

intrinsic identity conditions. We know that 1 + 1 = 2, for example, even

though someone might doubt that 1 + 1 is a prime number despite not

doubting that 2 is a prime number. We know that Mark Twain = Samuel

Clemens, regardless of whether or not someone happens to believe that

Mark Twain wrote Tom Sawyer while doubting that Samuel Clemens wrote

Tom Sawyer . Converse intentional properties invalidate Leibniz ’ Law as a

universal identity principle, which means that extrinsic converse intentional

properties should be barred from its applications. Unfortunately, Descartes ’

fi rst (Meditation 2) mind ≠ body argument commits precisely the “ intensional

fallacy ” of deducing the nonidentity of body and mind on the basis