## Cogito Ergo Sum

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• Sorry, this may be off topic , but I am just responding to Joe s question to me. Joe writes:
Message 1 of 9 , Feb 26, 2008
Sorry, this may be "off topic", but I am just responding to Joe's
question to me.

Joe writes:

<< Descartes' claim is that proceeding from 'I experience' to 'I am'
is not a syllogism --- what we today would call deduction by modus
ponens. Heidegger agrees; but, assumes that there is no other
justification for the 'ergo' in the cogito.

do you agree with that assumption?

I consider the forensic inference to be a rudimentary form of a
transcendental argument about a century before Kant developed it
more fully.

do you see any difference between a transcendental argument and a
deduction by modus ponens? >>

Wikipedia writes:

<< Modus ponens is a very common rule of inference, and takes the
following form:

If P, then Q.
P.
Therefore, Q.

A transcendental argument is a philosophical argument that starts
from what a person experiences, and then deduces what must be the
case for the person to have that experience. >>

Jim writes:

According to these definitions from wikipedia, transcendental
aruments are examples of modus ponens inferences, so if Descartes
did deny his "cogito ergo sum" was a modus ponens then he surely has
to also deny that it was a transcendental argument.

As I keep saying, Descartes was keen to avoid using logical
inference whilst he was doubting God's existence, so Descartes had a
good reason for denying that "cogito ergo sum" was a modus ponens
inference.

The rest of us can accept that "cogito ergo sum" is an example of
modus ponens. It also counts as a transcendental argument, according
to the above definition.

I am happy to accept that "cogito ergo sum" is a sound modus ponens
argument. But what significance has it got on its own? As far as I
can tell, it doesn't help one bit in my quest to know if I am an
immaterial soul, or a brain, or a Dasein.

Back to you, Joe.

Jim
• ... to see the difference between the two types of argument, try to put the cogito argument into the format of the modus ponens which you ve quoted ... let me
Message 2 of 9 , Feb 29, 2008
jimstuart51 wrote:

>>Descartes' claim is that proceeding from 'I experience' to 'I am' is
>>not a syllogism --- what we today would call deduction by modus
>>ponens. Heidegger agrees; but, assumes that there is no other
>>justification for the 'ergo' in the cogito.

>>do you agree with that assumption?

>>I consider the forensic inference to be a rudimentary form of a
>>transcendental argument about a century before Kant developed it more
>>fully.

>>do you see any difference between a transcendental argument and a
>>deduction by modus ponens?

>Wikipedia writes:

>Modus ponens is a very common rule of inference, and takes the
>following form:

>If P, then Q.
>P.
>Therefore, Q.

>A transcendental argument is a philosophical argument that starts
>from what a person experiences, and then deduces what must be the
>case for the person to have that experience.

>Jim writes:

>According to these definitions from wikipedia, transcendental
>aruments are examples of modus ponens inferences, so if Descartes
>did deny his "cogito ergo sum" was a modus ponens then he surely has
>to also deny that it was a transcendental argument.

to see the difference between the two types of argument, try to put the
cogito argument into the format of the modus ponens which you've quoted
above:

>I am happy to accept that "cogito ergo sum" is a sound modus ponens
>argument.

let me make sure I understand this.

Descartes claims that the cogito is not a syllogism (modus ponens); and,
Heidegger agrees.

you claim that Descartes was wrong to say that the cogito is not a
syllogism.

doesn't that mean that Heidegger is also wrong on this point?

Joe

--
Philosophy is, after all, done ultimately in the first person for the
first person. --- H-N Castaneda

@^@~~~~~~~~~~~~~~~~~~~~~~@^@
http://what-am-i.net
@^@~~~~~~~~~~~~~~~~~~~~~~@^@
• Joe, Cogito ergo sum as a Modus Ponens argument: If I think then I am I think Therefore I am As I have already said twice before, Descartes says cogito ergo
Message 3 of 9 , Feb 29, 2008
Joe,

"Cogito ergo sum" as a Modus Ponens argument:

If I think then I am
I think
Therefore I am

As I have already said twice before, Descartes says "cogito ergo sum"
is not a syllogism (modus ponens) because he cannot use logical
inference at the stage in his overall argument when he has doubted
everything (including the existence of God) and he has not yet got God
back through one of his proofs. (Reason: Whilst God's existence is in
doubt, he says that the evil demon could deceive him into believing
arithmetical fallacies or logical fallacies.)

Do you understand this point I am making?

I think Heidegger was just accepting Descartes conditions surrounding
the cogito. Thus Descartes says the cogito was not a syllogism (for
the reasons given above), so Heidegger went along with Descartes, for
the sake of argument.

Jim
• ... the first line If I think then I am would be the major premise, a general statement or universal principle that is known to be true. the second line is
Message 4 of 9 , Mar 1, 2008
jimstuart51 wrote:

>"Cogito ergo sum" as a Modus Ponens argument:

>If I think then I am
>I think
>Therefore I am

the first line 'If I think then I am' would be the major premise, a
general statement or universal principle that is known to be true. the
second line is the minor premise. in order to make a modus ponens
argument work, the two premises have to be known before the conclusion
is drawn.

compare this to Descartes' own description of his thought processes in
the Discourse on Method [CSM I, 127]:

I resolved to pretend that all the things that had ever entered my
mind were no more true than the illusions of my dreams. But
immediately I noticed that while I was trying thus to think everything
false, it was necessary that I, who was thinking this, was something.
And observing that this truth 'I am thinking, therefore I exist' was
so firm and sure that all the most extravagant suppositions of the
sceptics were incapable of shaking it, I decided that I could accept
it without scruple as the first principle of the philosophy that I was
seeking.

Next I examined attentively what I was. I saw that while I could
pretend that I had no body and that there was no world and no place
for me to be in, I could not for all that pretend that I did not
exist. I saw on the contrary that from the mere fact that I thought of
doubting the truth of other things, it followed quite evidently and
certainly that I existed; whereas if I had merely ceased thinking,
even if everthing else I had ever imagined had been true, I should
have had no reason to believe that I existed. From this I knew I was a
substance whose whole essence or nature is simply to think, and which
does not require any place, or depend on any material thing, in order
to exist. Accordingly this 'I' --- that is, the soul by which I am
what I am --- is entirely distinct from the body, and indeed is easier
to know than the body, and would not fail to be whatever it is, even
if the body did not exist.

After this I considered in general what is required of a proposition
in order for it to be true and certain; for, since I had just found
one that I knew to be such, I thought that I ought also to know what
this certainty consists in. I observed that there is nothing at all in
the proposition 'I am thinking, therefore I exist' to assure me that I
am speaking the truth, except that I see very clearly that in order to
think it is necessary to exist.

when you cast "cogito; ergo, sum" as a modus ponens you present the
major premise as "If I think then I am". the corresponding statement in
the quoted passage, "in order to think it is necessary to exist", does
not appear until the end of the passage --- after the conclusion 'I am

consequently, casting the cogito argument as a modus ponens or
hypothetical syllogism does not accurately represent Descartes' thought
processes.

>As I have already said twice before, Descartes says "cogito ergo sum"
>is not a syllogism (modus ponens) because he cannot use logical
>inference at the stage in his overall argument when he has doubted
>everything (including the existence of God) and he has not yet got God
>back through one of his proofs. (Reason: Whilst God's existence is in
>doubt, he says that the evil demon could deceive him into believing
>arithmetical fallacies or logical fallacies.)

>Do you understand this point I am making?

yes; but, you are trading on an ambiguity that needs clarification. you
are suggesting that the reasons Descartes gave for claiming the cogito
was not a syllogism are identical to his 'real reasons', the strategic
motives you say he had for claiming the cogito was not a syllogism.

>I think Heidegger was just accepting Descartes conditions surrounding
>the cogito. Thus Descartes says the cogito was not a syllogism (for
>the reasons given above), so Heidegger went along with Descartes, for
>the sake of argument.

Jim,

you sound like a mother who tells her children "if you ever see a
philosopher jump off a bridge for invalid reasons, you have to jump off
the bridge, too; but, as long as you're only doing it for the sake of
the argument, *your* reasons are valid even if his are not."

seriously, Jim, what are you trying to accomplish here?

let's say that you prove that you are correct to claim that the argument
in the cogito is a modus ponens; that Descartes was wrong to claim
it was not a syllogism; and, that Heidegger was wrong to agree with
Descartes that it was not a syllogism.

how could that possibly help Heidegger make a case against the cogito?

Heidegger's case is a two step process:

1. remove the 'ergo' from 'cogito; ergo, sum'
2. present a case against 'cogito, sum'

how does it help Heidegger if you prove that he was wrong to take that
first step?

Joe

--
Philosophy is, after all, done ultimately in the first person for the
first person. --- H-N Castaneda

@^@~~~~~~~~~~~~~~~~~~~~~~@^@
http://what-am-i.net
@^@~~~~~~~~~~~~~~~~~~~~~~@^@
• Joe, You write:
Message 5 of 9 , Mar 2, 2008
Joe,

You write:

<< seriously, Jim, what are you trying to accomplish here?

let's say that you prove that you are correct to claim that the
argument in the cogito is a modus ponens; that Descartes was wrong to
claim it was not a syllogism; and, that Heidegger was wrong to agree
with Descartes that it was not a syllogism.

how could that possibly help Heidegger make a case against the
cogito? >>

In my posts I have mainly been disputing some of the things you had
said.

ergo sum" as a "forensic inference" and a "transcendental argument".
I made the point that a transcendental argument was a type of modus
ponens (logical syllogism) argument, so you could not attribute it to
Descartes as he claimed the cogito was not a logical syllogism.

If the cogito argument is not to be a modus ponens argument, I don't
know how Descartes can justify the "therefore". It cannot be
the "therefore" of logical deduction for Descartes, so what can it be?

As regards "helping Heidegger make a case against the cogito", I
agree I have not been a great help to Heidegger, as I have not read
much Heidegger, and as you say, the central argument against the
cogito of B&T Part 2 was never written.

All I said "to help Heidegger" was that the whole of B&T
(particularly sections 12 & 13) can be read as an indirect argument
against Cartesianism, as Heidegger is putting forward an alternative
picture of the relationship between the individual and his world. I
find Heidegger's alternative picture more convincing as he argues
that the starting point for theoretical philosophizing is that the
individual finds himself already acting in his environment, and
philosophical contemplation is a secondary way-of-being which must be
seen as grounded in Dasein's basic state of being.

I am not sure that this thread is going anywhere. I am rather dubious
of your own project. You seem to be trying to construct an argument
on Heidegger's behalf, an argument he never got around to writing.
But you seem to be wanting to construct this missing argument for the
sole purpose of showing that the argument is no good.

Is that a fair account of your project?

Jim
• ... no. as I indicated in my initial post, I am interested in discussing the common ground shared by both Heidegger and Descartes. I even mentioned two
Message 6 of 9 , Mar 3, 2008
jimstuart51 wrote:

>Joe,

>You write:

>>seriously, Jim, what are you trying to accomplish here?

>>let's say that you prove that you are correct to claim that the
>>argument in the cogito is a modus ponens; that Descartes was wrong to
>>claim it was not a syllogism; and, that Heidegger was wrong to agree
>>with Descartes that it was not a syllogism.

>>how could that possibly help Heidegger make a case against the cogito?

>In my posts I have mainly been disputing some of the things you had
>said.

>ergo sum" as a "forensic inference" and a "transcendental argument".
>I made the point that a transcendental argument was a type of modus
>ponens (logical syllogism) argument, so you could not attribute it to
>Descartes as he claimed the cogito was not a logical syllogism.

>If the cogito argument is not to be a modus ponens argument, I don't
>know how Descartes can justify the "therefore". It cannot be
>the "therefore" of logical deduction for Descartes, so what can it be?

>As regards "helping Heidegger make a case against the cogito", I
>agree I have not been a great help to Heidegger, as I have not read
>much Heidegger, and as you say, the central argument against the
>cogito of B&T Part 2 was never written.

>All I said "to help Heidegger" was that the whole of B&T
>(particularly sections 12 & 13) can be read as an indirect argument
>against Cartesianism, as Heidegger is putting forward an alternative
>picture of the relationship between the individual and his world. I
>find Heidegger's alternative picture more convincing as he argues
>that the starting point for theoretical philosophizing is that the
>individual finds himself already acting in his environment, and
>philosophical contemplation is a secondary way-of-being which must be
>seen as grounded in Dasein's basic state of being.

>I am not sure that this thread is going anywhere. I am rather dubious
>of your own project. You seem to be trying to construct an argument
>on Heidegger's behalf, an argument he never got around to writing.
>But you seem to be wanting to construct this missing argument for the
>sole purpose of showing that the argument is no good.

>Is that a fair account of your project?

no. as I indicated in my initial post, I am interested in discussing the
common ground shared by both Heidegger and Descartes. I even mentioned
two statements that both would consider true: 'I am' and 'I know that I
am; but, not what I am'.

of course, any discussion of the common ground will have to take into
account Heidegger's missing attack on cartesianism. my post concluded:

"I am hoping this post will provoke discussion on at least these two
points:"

"* has the extent of the common ground been correctly described; or,
have I included too much or too little?"

"* how can Heidegger focus his case against the 'cogito sum' (or
cartesian thinking, generally) so that his own conclusions about dasein
survive undamaged?"

let's say we avoid a theoretical dispute as to whether there is or is
not a difference between a transcendental argument and an argument based
on modus ponens. what then? casting the cogito argument as a modus
ponens justifies the 'ergo' which Heidegger wants to remove from
'cogito; ergo, sum'.

suppose that you do, somehow, manage to justify removing the 'ergo',
what then? we are left with 'I am' which I claim both Heidegger and
Descartes would accept as true.

what do you say?

Joe

--
Philosophy is, after all, done ultimately in the first person for the
first person. --- H-N Castaneda

@^@~~~~~~~~~~~~~~~~~~~~~~@^@
http://what-am-i.net
@^@~~~~~~~~~~~~~~~~~~~~~~@^@
• Joe, You write:
Message 7 of 9 , Mar 3, 2008
Joe,

You write:

<< suppose that you do, somehow, manage to justify removing the 'ergo',
what then? we are left with 'I am' which I claim both Heidegger and
Descartes would accept as true.

what do you say? >>

Yes, I agree that both Descartes and Heidegger will accept the "I am"
as true, but for Descartes the "I" is a res cogitans whilst for
Heidegger it is a Dasein.

One of Heidegger's aims in B&T is to argue that we cannot rely on what
is "self-evident" when starting out in philosophy. We must look into
the history of ourselves and Western philosophy as far back as the
Greeks, in order to clear away aspects of false consciousness.

Heidegger argues that traditional ontology has failed to investigate
adequately how "the central problematic of all ontology is rooted in
the phenomenon of time" (p. 40). Descartes is a prime example of a
philosopher who seeks to characterize the "I" of self-consciousness
without taking into account the temporality of Being.

Here are some quotes from the Introduction to "Being and Time" which
touch on this issue:

"Tradition takes what comes down to us and delivers it over to
which the categories and concepts handed down to us have been in part
quite genuinely drawn. Indeed it makes us forget that they have had
such an origin, and makes us suppose that the necessity of going back
to these sources is something which we need not even understand." (p. 43)

"[W]e must in the first instance raise the question whether and to
what extent the Interpretation of Being and the phenomenon of time
have been brought together thematically in the course of the history
of ontology, and whether the problematic of Temporality required for
this has ever been worked out in principle or ever could have been.
The first and only person who has gone any stretch of the way towards
investigating the dimension of Temporality or has even let himself be
drawn hither by the coercion of the phenomena themselves is Kant. .
[However] he failed to provide an ontology with Dasein as its theme or
(to put it in Kantian language) to give a preliminary ontological
analytic of the subjectivity of the subject. Instead of this, Kant
took over Descartes' position quite dogmatically, notwithstanding all
the essential respects in which he had gone beyond him. Furthermore,
in spite of the fact that he was bringing the phenomenon of time back
into the subject again, his analysis of it remained oriented towards
the long run this kept him from working out the phenomenon of a
`transcendental determination of time' in its own structure and
function. Because of this double effect of tradition the decisive
connection between time and the `I think' was shrouded in utter
darkness; it did not even become a problem.

In taking over Descartes' ontological position Kant made an essential
omission: he failed to provide an ontology of Dasein. This omission
was a decisive one in the spirit [im Sinne] of Descartes' ownmost
Tendencies. With the `cogito sum' Descartes had claimed that he was
putting philosophy on a new and firm footing. But what he left
undetermined when he began in this `radical' way, was the kind of
Being which belongs to the res cogitans, or  more precisely  the
meaning of the Being of the `sum'. By working out the unexpressed
ontological foundations of the `cogito sum', we shall complete our
sojourn at the second station along the path of our destructive
retrospect of the history of ontology. Our Interpretation will not
only prove that Descartes had to neglect the question of Being
altogether; it will also show why he came to suppose that the absolute
`Being-certain' ["gewissein"] of the cogito exempted him from raising
the question of the meaning of the Being which this entity
possesses.""(pp. 44-6)

Heidegger goes on for two more paragraphs sketching out how and where
Descartes went wrong. Admittedly this is only a preliminary sketch for
the missing argument of B&T Part 2, but I think there is enough in B&T
to form a strong case against Cartesianism.

I read Heidegger's argument as a bit like how a person who believes
that the earth rotates around the sun (every year), and around its own
axis (every day) might try to convert the person who thinks that the
earth is stationary. The person who thinks that the earth is
stationary appeals to "self-evidence" in the same manner that
Descartes does with his "cogito ergo sum". The person who believes
that the earth moves has to appeal to a background theory to convince
the other that what he thinks is self-evident is in fact false.
Similarly, Heidegger has to spend a long time drawing up a complex
background theory to show how supposed self-evident Cartesianism is in
fact mistaken.

Yes, it is a pity, Heidegger never got around to writing Part 2 of
B&T, but even without a direct argument against Descartes' cogito, I
think Heidegger does enough to undermine Descartes' viewpoint.

As I have said before, Heidegger, like all philosophical geniuses, is
trying to replace an ingrained picture of ourselves with a radically
different one, and this takes a lot of hard work by both author and

"The question of Being does not achieve its true concreteness until we
have carried through the process of destroying the ontological

Finally, I'd like to thank you, Joe, for your thought-provoking and
well-argued posts. If nothing else, you have got me reading "Being and
Time" again.

Jim
• Two of Heidegger s texts have been described by scholars as the virtual Vol II of B&T: The Basic Problems of Phenomenology ; and Contributions to Philosophy
Message 8 of 9 , Mar 3, 2008
Two of Heidegger's texts have been described by scholars as the virtual
Vol II of B&T: "The Basic Problems of Phenomenology"; and
"Contributions to Philosophy - From Enowning" (usually called The
Enowning Texts). The latter seems the more germane and is certainly the
more interesting.

Wil

-----Original Message-----
From: jimstuart51 <jjimstuart1@...>
To: existlist@yahoogroups.com
Sent: Mon, 3 Mar 2008 11:36 am
Subject: [existlist] Re: Cogito Ergo Sum

Joe,

You write:

<< suppose that you do, somehow, manage to justify removing the 'ergo',

what then? we are left with 'I am' which I claim both Heidegger and

Descartes would accept as true.

what do you say? >>

Yes, I agree that both Descartes and Heidegger will accept the "I am"

as true, but for Descartes the "I" is a res cogitans whilst for

Heidegger it is a Dasein.

One of Heidegger's aims in B&T is to argue that we cannot rely on what

is "self-evident" when starting out in philosophy. We must look into

the history of ourselves and Western philosophy as far back as the

Greeks, in order to clear away aspects of false consciousness.

Heidegger argues that traditional ontology has failed to investigate

adequately how "the central problematic of all ontology is rooted in

the phenomenon of time" (p. 40). Descartes is a prime example of a

philosopher who seeks to characterize the "I" of self-consciousness

without taking into account the temporality of Being.

Here are some quotes from the Introduction to "Being and Time" which

touch on this issue:

"Tradition takes what comes down to us and delivers it over to

which the categories and concepts handed down to us have been in part

quite genuinely drawn. Indeed it makes us forget that they have had

such an origin, and makes us suppose that the necessity of going back

to these sources is something which we need not even understand." (p.
43)

"[W]e must in the first instance raise the question whether and to

what extent the Interpretation of Being and the phenomenon of time

have been brought together thematically in the course of the history

of ontology, and whether the problematic of Temporality required for

this has ever been worked out in principle or ever could have been.

The first and only person who has gone any stretch of the way towards

investigating the dimension of Temporality or has even let himself be

drawn hither by the coercion of the phenomena themselves is Kant. ….

[However] he failed to provide an ontology with Dasein as its theme or

(to put it in Kantian language) to give a preliminary ontological

analytic of the subjectivity of the subject. Instead of this, Kant

took over Descartes' position quite dogmatically, notwithstanding all

the essential respects in which he had gone beyond him. Furthermore,

in spite of the fact that he was bringing the phenomenon of time back

into the subject again, his analysis of it remained oriented towards

the long run this kept him from working out the phenomenon of a

`transcendental determination of time' in its own structure and

function. Because of this double effect of tradition the decisive

connection between time and the `I think' was shrouded in utter

darkness; it did not even become a problem.

In taking over Descartes' ontological position Kant made an essential

omission: he failed to provide an ontology of Dasein. This omission

was a decisive one in the spirit [im Sinne] of Descartes' ownmost

Tendencies. With the `cogito sum' Descartes had claimed that he was

putting philosophy on a new and firm footing. But what he left

undetermined when he began in this `radical' way, was the kind of

Being which belongs to the res cogitans, or – more precisely – the

meaning of the Being of the `sum'. By working out the unexpressed

ontological foundations of the `cogito sum', we shall complete our

sojourn at the second station along the path of our destructive

retrospect of the history of ontology. Our Interpretation will not

only prove that Descartes had to neglect the question of Being

altogether; it will also show why he came to suppose that the absolute

`Being-certain' ["gewissein"] of the cogito exempted him from raising

the question of the meaning of the Being which this entity

possesses.""(pp. 44-6)

Heidegger goes on for two more paragraphs sketching out how and where

Descartes went wrong. Admittedly this is only a preliminary sketch for

the missing argument of B&T Part 2, but I think there is enough in B&T

to form a strong case against Cartesianism.

I read Heidegger's argument as a bit like how a person who believes

that the earth rotates around the sun (every year), and around its own

axis (every day) might try to convert the person who thinks that the

earth is stationary. The person who thinks that the earth is

stationary appeals to "self-evidence" in the same manner that

Descartes does with his "cogito ergo sum". The person who believes

that the earth moves has to appeal to a background theory to convince

the other that what he thinks is self-evident is in fact false.

Similarly, Heidegger has to spend a long time drawing up a complex

background theory to show how supposed self-evident Cartesianism is in

fact mistaken.

Yes, it is a pity, Heidegger never got around to writing Part 2 of

B&T, but even without a direct argument against Descartes' cogito, I

think Heidegger does enough to undermine Descartes' viewpoint.

As I have said before, Heidegger, like all philosophical geniuses, is

trying to replace an ingrained picture of ourselves with a radically

different one, and this takes a lot of hard work by both author and

"The question of Being does not achieve its true concreteness until we

have carried through the process of destroying the ontological

Finally, I'd like to thank you, Joe, for your thought-provoking and

well-argued posts. If nothing else, you have got me reading "Being and

Time" again.

Jim
• Thanks, Wil. I shall add these texts to my reading list. Jim
Message 9 of 9 , Mar 4, 2008
Thanks, Wil.

Jim

--- In existlist@yahoogroups.com, eupraxis@... wrote:
>
> Two of Heidegger's texts have been described by scholars as the virtual
> Vol II of B&T: "The Basic Problems of Phenomenology"; and
> "Contributions to Philosophy - From Enowning" (usually called The
> Enowning Texts). The latter seems the more germane and is certainly the
> more interesting.
>
> Wil
>
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