## The logic of "Cogito ergo sum"

Philosophical, mathematical and computational logic, linguistics, formal argument, game theory, fallacies, paradoxes, puzzles and other related issues.

### The logic of "Cogito ergo sum"

Could someone tell me how Descartes came to the logical statement think()≡exist()├(think(self)├exist(self))? I.E. The function of thinking is equivalent to the function of existing therefore function think of "self" implies function exist of "self". I'm referring to the popular phrase "Cogito ergo sum" (I think therefore I am). What makes the function of thinking and the function of existing equivalent in their products? Do they have the same formula? If not, then are they only distinguishable by syntax (semantics)?

It seems to me that Descartes assumed that the self existed because it was psychologically appealing. Could you imagine yourself not existing? Of course not, you end up in some kind of morbid blanka rosa thought. He figured that if there is an "I" that thinks then there is an "I" that be. But, as said, this is egotistic and makes the assumption of "I" because we are presumably encapsulated in subject "I".

So how can one know that they exist through logical means? Is it only by instinct, intuition, and social relation that we develop concept of self and become self-aware?
avanover

### Re: The logic of "Cogito ergo sum"

Hello avanover,

Well I would rather say: it is by observation that we become self-aware. But you are right: cogito, like most of Descartes' work (mathematics aside) was by today's standards, bad logic.

Lomax

Lomax

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### Re: The logic of "Cogito ergo sum"

I have a big problem with the statrment. The closest I have got to finding a proper gauge to define ones' own existence is "I think therefore I thought, I can prove I thought therefore I am" Its a thorny question and leaves much to interpretation. Its logic is very suspect by todays standards. You may like to view the postings on "Philosophy of the self" in anything philosophy and you will see what I mean. I wish you luck!
Louis_B

### Re: The logic of "Cogito ergo sum"

Hello Louis B,

Louis_B wrote:I have a big problem with the statrment. The closest I have got to finding a proper gauge to define ones' own existence is "I think therefore I thought, I can prove I thought therefore I am"

It doesn't follow anyway. "I think therefore I thought" is a token-reflexive fallacy, and "I can prove I thought" doesn't follow from the rest. I would suggest that, for all its flaws, "I think therefore I am" is a more tenable argument than the one you suggest.

Lomax

Lomax

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### Re: The logic of "Cogito ergo sum"

I think the problem you are having is making use of 'ergo' as if it implies the result of an argument that can be subjected to logic. (Of course it can be and in fact it has usefully been critiqued in this way. However...) While it may be a conclusion on the part of Descartes that we are thinking beings, or perhaps initially are thinking things so long as we are thinking, or even more specifically, so long as we are aware we are doubting (considered as a subset of thinking, generally), this is the result of his reaching it by his method of doubt, not by logic. He is looking for certainty in knowledge by seeking justification in a different way entirely. Truth seeking isn't entirely in the hands of logic, imho. Indeed, to what extent has logic supplied us with certain knowledge? Possibly in the domains of mathematics and computer science. But where logic fits in, in my view, is in being helpful by telling us why our arguments are good or bad. In doing so they may contribute to the acquisition of knowledge, but I don't think they are a substitute for it. Knowledge acquisition and its justification have qualities about them seem to supervene the formal structures laid down by logic. (imho)

James
owleye

### Re: The logic of "Cogito ergo sum"

Greetings everybody.

I think we are probably dealing with an enthymeme here. The expression:

I think therefore I exist.

Can be rephrased like:

1. I think.
C. I exist.

Of course, if you look the argument that way, you will simply say "it is wrong, that doesn't follow". But let us return to Carnap for a moment and let us involve charity. If we put Descartes's dictum in a context, we may say there is a missing premise there, which is: "Everything that thinks, exists", because we have to remember that "thinking", for Descartes, was a substance, the "thinking substance". So, if we add the missing premise, we get:

1. I think ::= Tj
2. Everything that thinks, exists ::= (∀x)(Tx > (∃y)x=y)
C. I exist ::= (∃x)j=x

Which is valid, maybe trivial, but valid anyway. I think it is not a problem of logic in any case, but a problem with the soundness of the premises: that "thinking substance" turns out to be a "tricky substance".

Cheers.
1900

### Re: The logic of "Cogito ergo sum"

owleye wrote:I think the problem you are having is making use of 'ergo' as if it implies the result of an argument that can be subjected to logic. (Of course it can be and in fact it has usefully been critiqued in this way. However...) While it may be a conclusion on the part of Descartes that we are thinking beings, or perhaps initially are thinking things so long as we are thinking, or even more specifically, so long as we are aware we are doubting (considered as a subset of thinking, generally), this is the result of his reaching it by his method of doubt, not by logic. He is looking for certainty in knowledge by seeking justification in a different way entirely. Truth seeking isn't entirely in the hands of logic, imho. Indeed, to what extent has logic supplied us with certain knowledge? Possibly in the domains of mathematics and computer science. But where logic fits in, in my view, is in being helpful by telling us why our arguments are good or bad. In doing so they may contribute to the acquisition of knowledge, but I don't think they are a substitute for it. Knowledge acquisition and its justification have qualities about them seem to supervene the formal structures laid down by logic. (imho)

James

Well, I generally consider logic the law of sound thought. So all verifiable knowledge must be linked with logic in some way. You make foundations and then build upon them to discover more. For logic to work at all we have to, of course, have data. The data comes from sensory perception. So it's necessary to trust the senses in order to be knowledgeable. The only time that we shouldn't trust our senses is when we recognize that it's an illusion and we can do this very simply.

Ask a person whether or not they sense particular objects exist and ask if they sense certain properties of those objects. Since you both share a high number of synchronicities then it is probable (and practical) that you both share a common perceived reality (which would imply that this reality exist of your collective minds or exists externally to your minds). Whenever there is an inconsistency with your common perceived reality then you understand one or the other to be an illusion. Usually you pick the one which is least likely to be the illusion (and this requires a posteriori knowledge of this reality).

Now, if one is person is illusory then the other is either referring to himself or the illusion was constructed by an unknown entity which is referring to the other. In either case: either yourself is referring to yourself or something else is referring to yourself. Therefore, the self exists. If both persons are illusory then whence cometh perception? How can illusion refer to illusion? So, I think social interaction (and necessary brain matter) first allowed for self-awareness and introspection (an abstract process derived from extrospection, the self is part of the world so it's first necessary to observe the world).

Anyways, this is the idea that I've come to. Perhaps someone could put it in formal modal logic. Thank you for all your responses. Please critique where necessary.
avanover

### Re: The logic of "Cogito ergo sum"

1900 wrote:Greetings everybody.

I think we are probably dealing with an enthymeme here. The expression:

I think therefore I exist.

Can be rephrased like:

1. I think.
C. I exist.

Of course, if you look the argument that way, you will simply say "it is wrong, that doesn't follow". But let us return to Carnap for a moment and let us involve charity. If we put Descartes's dictum in a context, we may say there is a missing premise there, which is: "Everything that thinks, exists", because we have to remember that "thinking", for Descartes, was a substance, the "thinking substance". So, if we add the missing premise, we get:

1. I think ::= Tj
2. Everything that thinks, exists ::= (∀x)(Tx > (∃y)x=y)
C. I exist ::= (∃x)j=x

Which is valid, maybe trivial, but valid anyway. I think it is not a problem of logic in any case, but a problem with the soundness of the premises: that "thinking substance" turns out to be a "tricky substance".

Cheers.

Premise two is the similar of the "thinking" function being equivalent to the "existing" function (which is the odd way that I understand it, haha). I suppose this is something which is up to debate in metaphysics. I can see where panpsychism originally comes from.
avanover

### Re: The logic of "Cogito ergo sum"

Edit
Last edited by 1900 on August 6th, 2010, 10:01 pm, edited 1 time in total.
1900

### Re: The logic of "Cogito ergo sum"

Greetings, anaover.

avanover wrote:Premise two is the similar of the "thinking" function being equivalent to the "existing" function (which is the odd way that I understand it, haha). I suppose this is something which is up to debate in metaphysics. I can see where panpsychism originally comes from.

While I don't understand exactly why you use the word "function" (a Fregean interpretation maybe?), I can see your point very clearly. Indeed, the problem seems to be a metaphysical one, not a logical. Now let me say something else regarding this metaphysical problem: there is no need to interpret Descartes' dictum (Dd) as an equivalence between "to think" and "to exist"; we only need one direction of the implication which, in Descartes' opinion, goes from "think" to "exist", and not the other way around (because the other substance is non-thinking and yet, exists). So, having said that, I think Dd is quite appealing because of the following: the negation of it leads to a contradiction.

My two cents.
1900

### Re: The logic of "Cogito ergo sum"

avanover wrote:Well, I generally consider logic the law of sound thought. So all verifiable knowledge must be linked with logic in some way. You make foundations and then build upon them to discover more. For logic to work at all we have to, of course, have data. The data comes from sensory perception. So it's necessary to trust the senses in order to be knowledgeable. The only time that we shouldn't trust our senses is when we recognize that it's an illusion and we can do this very simply.

If I grant the first two claims, in what way does the rest of the paragraph help in understanding the way knowledge is linked with logic? I hope it wasn't intended to support it, because I don't see the connection.

avanover wrote:Ask a person whether or not they sense particular objects exist and ask if they sense certain properties of those objects. Since you both share a high number of synchronicities then it is probable (and practical) that you both share a common perceived reality (which would imply that this reality exist of your collective minds or exists externally to your minds). Whenever there is an inconsistency with your common perceived reality then you understand one or the other to be an illusion. Usually you pick the one which is least likely to be the illusion (and this requires a posteriori knowledge of this reality).

Interesting you find the need to support your position about easily dispelling illusions and how you go about doing so. It has the ring of a psychological explanation. If a knowledge claim is disputed it makes sense then yes, I suppose, alternative claims might be considered, but unless there is a dispute (when, for example, we always hang around those who believe the same things we do), then I'm not so sure it can be rendered as a problem 'easily" overcome. Rather than switch to the "most likely", whatever that means, it might be that we dig in our heels and claim the disputants are wrong.

In any case, I'm thinking here that what is needed is a philosophical reason to support your claims, not a psychological one. In philosophy, epistemology is not a science and so it would be appropriate, I think, to heed to some of the difficulties philosophers have with knowledge. Terms like 'most likely' and 'trust' may be interesting observations of the way you go about gaining knowledge, but if you're going to argue this viewpoint, then it's going to sound like what you mean by 'truth' is having a certain kind of loyalty to what one believes in (as, for example, it is used in the notion of 'true love' or 'true to one's word'. If this is attractive to you, then go for it. I can't see as how logic plays a role in it, however.

James
owleye

### Re: The logic of "Cogito ergo sum"

owleye wrote:
avanover wrote:Well, I generally consider logic the law of sound thought. So all verifiable knowledge must be linked with logic in some way. You make foundations and then build upon them to discover more. For logic to work at all we have to, of course, have data. The data comes from sensory perception. So it's necessary to trust the senses in order to be knowledgeable. The only time that we shouldn't trust our senses is when we recognize that it's an illusion and we can do this very simply.

If I grant the first two claims, in what way does the rest of the paragraph help in understanding the way knowledge is linked with logic? I hope it wasn't intended to support it, because I don't see the connection.

avanover wrote:Ask a person whether or not they sense particular objects exist and ask if they sense certain properties of those objects. Since you both share a high number of synchronicities then it is probable (and practical) that you both share a common perceived reality (which would imply that this reality exist of your collective minds or exists externally to your minds). Whenever there is an inconsistency with your common perceived reality then you understand one or the other to be an illusion. Usually you pick the one which is least likely to be the illusion (and this requires a posteriori knowledge of this reality).

Interesting you find the need to support your position about easily dispelling illusions and how you go about doing so. It has the ring of a psychological explanation. If a knowledge claim is disputed it makes sense then yes, I suppose, alternative claims might be considered, but unless there is a dispute (when, for example, we always hang around those who believe the same things we do), then I'm not so sure it can be rendered as a problem 'easily" overcome. Rather than switch to the "most likely", whatever that means, it might be that we dig in our heels and claim the disputants are wrong.

In any case, I'm thinking here that what is needed is a philosophical reason to support your claims, not a psychological one. In philosophy, epistemology is not a science and so it would be appropriate, I think, to heed to some of the difficulties philosophers have with knowledge. Terms like 'most likely' and 'trust' may be interesting observations of the way you go about gaining knowledge, but if you're going to argue this viewpoint, then it's going to sound like what you mean by 'truth' is having a certain kind of loyalty to what one believes in (as, for example, it is used in the notion of 'true love' or 'true to one's word'. If this is attractive to you, then go for it. I can't see as how logic plays a role in it, however.

James

Religious beliefs are an abstraction and this is why it's illogical to go with the majority. It's not the same with direct sensory perception which gives us immediate data. I mentioned above how to tell whether or not the data is artificial or not. The fact is, we can't for sure, but we can use modal logic to see which is most practical and usable. It's something that all agree on (unless experiencing illusion, virtually none in everyday experience). Technically, you might say that we have a faith in our sensory perceptions but the mind will inquire "What alternative is there?". Therefore, there is good reason for this "faith" (practicality). Religious beliefs need to be tested on data which is founded on our common perceived reality. Logic is used to verify them. People observe and verify with logic and we then understand our observations to be true and we now have knowledge. Loyalty to belief is more equivalent to faith than truth. "True love" is actually a misnomer, accurately it would read "Faithful love". It's like I said "logic is the law of sound thought".
avanover

### Re: The logic of "Cogito ergo sum"

avanover wrote:Religious beliefs are an abstraction and this is why it's illogical to go with the majority. It's not the same with direct sensory perception which gives us immediate data. I mentioned above how to tell whether or not the data is artificial or not. The fact is, we can't for sure, but we can use modal logic to see which is most practical and usable. It's something that all agree on (unless experiencing illusion, virtually none in everyday experience). Technically, you might say that we have a faith in our sensory perceptions but the mind will inquire "What alternative is there?". Therefore, there is good reason for this "faith" (practicality). Religious beliefs need to be tested on data which is founded on our common perceived reality. Logic is used to verify them. People observe and verify with logic and we then understand our observations to be true and we now have knowledge. Loyalty to belief is more equivalent to faith than truth. "True love" is actually a misnomer, accurately it would read "Faithful love". It's like I said "logic is the law of sound thought".

You seem to ask a lot of charity, by which I mean your claims require considerable work on my part to find a charitable appreciation of what you mean. Apparently you are using 'logic' in a different way than I at first read what you declared about logic being the law of thought. I had originally taken it as an imperative. We ought to think logically. But, assuming this is what you had in mind, then given the form: It is illogical to think that MR is a principle that should be applied to RB, because RB is an A. We are not thinking logically when we make such a claim. However, this doesn't really make sense. On this view, it would seem, all implications with this form are illogical. An awful lot has to be filled in (and this is where charity is supposed to help out) before it can make sense. Others may be able to read between the lines, but I'm afraid I'm not able to at this time.

In any case, I'm glad to see you are not advocating the interpretation of truth that sides with loyalty or is based on faith. But for me to proceed I need a bit more clarification. At the moment, it seems your use of logic has more kinship with our being rational about our judgments. While it is couched in terms of a kind of methodological argument, which I find a bit misleading, its essence seems to be that we should rely on our ability to reason to make decisions. Adam Smith and his followers, believed, generally speaking, we do just that. Recent economists seem to have taken up a different position, some emphasizing our emotions, others, being behavioral economists, make use of pain/pleasure principles. Anyway, this is getting pretty far away from the logic of the topic.

James
owleye

### Re: The logic of "Cogito ergo sum"

owleye wrote:
avanover wrote:Religious beliefs are an abstraction and this is why it's illogical to go with the majority. It's not the same with direct sensory perception which gives us immediate data. I mentioned above how to tell whether or not the data is artificial or not. The fact is, we can't for sure, but we can use modal logic to see which is most practical and usable. It's something that all agree on (unless experiencing illusion, virtually none in everyday experience). Technically, you might say that we have a faith in our sensory perceptions but the mind will inquire "What alternative is there?". Therefore, there is good reason for this "faith" (practicality). Religious beliefs need to be tested on data which is founded on our common perceived reality. Logic is used to verify them. People observe and verify with logic and we then understand our observations to be true and we now have knowledge. Loyalty to belief is more equivalent to faith than truth. "True love" is actually a misnomer, accurately it would read "Faithful love". It's like I said "logic is the law of sound thought".

You seem to ask a lot of charity, by which I mean your claims require considerable work on my part to find a charitable appreciation of what you mean. Apparently you are using 'logic' in a different way than I at first read what you declared about logic being the law of thought. I had originally taken it as an imperative. We ought to think logically. But, assuming this is what you had in mind, then given the form: It is illogical to think that MR is a principle that should be applied to RB, because RB is an A. We are not thinking logically when we make such a claim. However, this doesn't really make sense. On this view, it would seem, all implications with this form are illogical. An awful lot has to be filled in (and this is where charity is supposed to help out) before it can make sense. Others may be able to read between the lines, but I'm afraid I'm not able to at this time.

In any case, I'm glad to see you are not advocating the interpretation of truth that sides with loyalty or is based on faith. But for me to proceed I need a bit more clarification. At the moment, it seems your use of logic has more kinship with our being rational about our judgments. While it is couched in terms of a kind of methodological argument, which I find a bit misleading, its essence seems to be that we should rely on our ability to reason to make decisions. Adam Smith and his followers, believed, generally speaking, we do just that. Recent economists seem to have taken up a different position, some emphasizing our emotions, others, being behavioral economists, make use of pain/pleasure principles. Anyway, this is getting pretty far away from the logic of the topic.

James

An abstraction is something which only exists in the mind, e.g. religious belief. Argumentum ad populum is a logical fallacy which means "appeal to the people". It alleges "If many believe so, it is so". Things which are not abstractions, such as direct sensory perception, are not abstractions and thus a common perceived reality does not follow with the Argumentum ad populum fallacy. Sorry for not making myself very clear, hope this helps. So here's the logic of my statement:

Religious belief is a type of abstraction.
Abstraction is that which only exists in the mind, by definition.
That which only exists in the mind not necessarily true.
Religious belief, is thus, not necessarily true.
Therefore, it's illogical to concede religious belief is necessarily true because the majority believe so.
avanover

### Re: The logic of "Cogito ergo sum"

Lomax wrote:Hello avanover,

Well I would rather say: it is by observation that we become self-aware. But you are right: cogito, like most of Descartes' work (mathematics aside) was by today's standards, bad logic.

Lomax

I don't see the bad logic here.

If we define 'x exists' as there is some property that x has, then, I think implies I exist.
That is, if x has any particular property, then x exists.
I pee therefore I am, works too.
To be is to have a property.

Gx -> (x exists), for any primary predicate G. ie. Gx -> EF(Fx), is a theorem.
Gx -> (G exists), for any primary subject x. ie. Gx -> Ef(f(G)).
Owen4x

### Re: The logic of "Cogito ergo sum"

Hello Owen4x,

Well I don't deny that Ex(Tx & Ix) -> Ex(Ix) under most or all agreeable formal systems; I charge Descartes with bad logic because he wanted to prove much more than this; he wanted to show that Ex(Ix) is a priori and necessary, and that it can serve as an epistemic first principle. Here are my problems with that (and we already have loads of threads about this, by the way):

1. Ex(Tx&Ix) is not, itself, a priori and necessary
2. Descartes assumes foundationalism; that is, the a priori necesssity of logical deductions such as Ex(Tx & Ix) -> Ex(Ix) has yet to be established.
3. Descartes already accepts some form of logical axiom in order to call this deduction valid, and so, dubito cogito ergo sum is at best his second principle.

In other words: while I agree with you that the deduction is valid, I also agree with Avanover that Descartes did not establish what he wanted.

Lomax

Lomax

Posts: 3711
Joined: 01 Jul 2010
Location: Nuneaton, UK

### Re: The logic of "Cogito ergo sum"

Lomax wrote:Well I would rather say: it is by observation that we become self-aware. But you are right: cogito, like most of Descartes' work (mathematics aside) was by today's standards, bad logic.

Descartes' math was also bad logic by today's standards, too. Nobody reads his mathematics, of course, so this is not widely known.

From Reuben Hersh's What is Mathematics, Really? (2000):

Emily Grosholz and Carl Boyer point out errors in [Descartes'] Geometry. "When he turns his attention to the locus of five lines, he considers only a few cases, not bothering to complete the task, because, as he says, his method furnishes a way to describe them. But Descartes could not have completed the task, which amounted to giving a catalogue of the cubics.... Newton, because he was able to move with confidence between graph and equation, first attempted a catalogue of the cubics; he distinguished seventy-two species of cubics, and even then omitted six" ( Grosholz, referring to Whiteside).

"Descartes stratified his hierarchy into levels of pairs of degrees, since (so he thought) from curves of degree n and n + 1 his apparatus of hinged rulers produced curves of degree n + 2 and n + 3. Fermat gave a counter-example to this generalization.

"Descartes classification into orders of two degrees each was based on the fact that the algebraic solution of the quartic leads to a resolvent cubic from which Descartes rashly concluded--incorrectly, as Hudde later showed--that an equation of degree 2n would in all cases lead to a resolvent of degree 2n - 1. . . . The method Descartes proposed for the study of the properties of a space curve is to project it upon two mutually perpendicular planes and to consider the two curves of projection. Unfortunately, the only illustrative property given here is erroneous for one reads that the normal to a curve in three-space at a point P on the curve is the line of intersection of the two planes through P, determined by the normal lines to the curves of projection at the points corresponding to P. This would be true of the tangent line, but does not in general hold for a normal.... Descartes, in these casual remarks, seems not to have been aware of the fact that for space of more than two dimensions a normal is not uniquely determined for a point on a curve."

(pg. 114)
xcthulhu

### Re: The logic of "Cogito ergo sum"

I clearly am in over my head dealing with folks who are comfortable working within the language of symbolic logic. I can recognize but not use sybolic logic. But I too have a problem with the cognito. It seems to me that "I think" leads clearly to "something thinks". And "something thinks" can clearly support the existence of that something. However the identification of the thing that thinks with "I" seems a bit shaky.
Charles miller

### Re: The logic of "Cogito ergo sum"

Truth seeking isn't entirely in the hands of logic
Agreed.
Logic has a certain ‘want to be’ as to its outcome, however there are truths that are championed not from logic but from emotion, and in human nature its seldom a mechanised dogma that dictates the outcome , think of the analogy in star wars. robots verse humans As if it were not logical that this empire could defeat the normal person

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### Re: The logic of "Cogito ergo sum"

avanover wrote:An abstraction is something which only exists in the mind, e.g. religious belief. Argumentum ad populum is a logical fallacy which means "appeal to the people". It alleges "If many believe so, it is so". Things which are not abstractions, such as direct sensory perception, are not abstractions and thus a common perceived reality does not follow with the Argumentum ad populum fallacy. Sorry for not making myself very clear, hope this helps. So here's the logic of my statement:

Religious belief is a type of abstraction.
Abstraction is that which only exists in the mind, by definition.
That which only exists in the mind not necessarily true.
Religious belief, is thus, not necessarily true.
Therefore, it's illogical to concede religious belief is necessarily true because the majority believe so.

My apologies. I hadn't noticed this response of yours until the recent post showed up in my "Your posts". Ok, I think I understand. I wouldn't have used the term 'illogical', and instead merely regard it as fallacious reasoning. Moreover, I wouldn't think you need anything like "necessarily true" to make your case. This seems too strong. Mere "true" would have covered it, I think. Nevertheless, what you say is now clearer in my mind.

James
owleye

### Re: The logic of "Cogito ergo sum"

I havn't read the whole thread but I would like to make a few comments. First, "I think therefore I am" was to me the most common sense thing I ever heard before I even knew what philosophy was. What I mean by that is; for philosophers to reevalute it is fine, but if they could replace it by an equally short and accessible, yet more accurate phrase, what would it be? Secondly last year I read Meditations, and I remember some insights I made. Descartes' Cogito ergo sum was followed by his proofs in God, included the one as follows: a person who knows of perfection, can't found himself, because then he would have been perfect. My thought on this is that he didn't nessesarily mean an empty consept that can never be fullfilled, but that he actually believed he saw perfection in his own cogito or consciousness. Mabye everything and anything we percieve can be further perfected except our own sense of self. People of course talk of states of higher (or more perfect) conscioussness even in his time but he could have overlooked that. Then this diffucult to explain 'perfection' which he percieved, was God to him.
stuartp523

### Re: The logic of "Cogito ergo sum"

stuartp523 wrote:I havn't read the whole thread but I would like to make a few comments. First, "I think therefore I am" was to me the most common sense thing I ever heard before I even knew what philosophy was. What I mean by that is; for philosophers to reevalute it is fine, but if they could replace it by an equally short and accessible, yet more accurate phrase, what would it be? ...

No problem. Philosophers have been tackling "common sense" and the obvious for as long as philosophy has been around. You might consider "Cogito ergo sum" as a stepping stone in the understanding of who we are. On the empirical side of things, the ego portion of this has undergone quite a bit of skepticism, especially as it is reduced to a logic, while on the phenomenological side of things, it retains considerable power, one that "throws itself" into the world, doing so, behind a veil of emptiness, making it even more powerful.

James
owleye

### Re: The logic of "Cogito ergo sum"

Charles miller wrote:I clearly am in over my head dealing with folks who are comfortable working within the language of symbolic logic. I can recognize but not use sybolic logic. But I too have a problem with the cognito. It seems to me that "I think" leads clearly to "something thinks". And "something thinks" can clearly support the existence of that something. However the identification of the thing that thinks with "I" seems a bit shaky.

I really am glad I stumbled upon this thread. This issue of the problem with Descartes's statement vexes me as well. I think the best alternative comes from the realm of Zen Buddhism.

http://www.dharmafield.org/coursehandouts/dependentarising/ergosum.pdf

From Steve Hagen:

--
"To get his statement more in line with direct experience, Descartes might have said “cogitatio ergo esse”—“Thought, therefore to be.” Or, “Thought, therefore existence.” Thought, therefore something (without naming it) is. Something’s going on, in other words.*

*But the word “esse”—“to be, to exist”—is still not quite reflective of actual experience, for it has a static quality about it. Since all our experience is in (or of) time, the phrase “thought is to be” does not quite hit the mark, for “to be” implies an abiding, unchanging thing. To get closer to actual experience, then, Descartes might have said “cogitatio ergo existere,” or better yet, “sensus ergo existere” (consciousness, therefore becoming)."

--

So "sensus ergo existere" might be the best replacement :)
Doug0915

### Re: The logic of "Cogito ergo sum"

What if you read the phrase, not as a philosophical axiom, nor as a logical formula, but as the recounting of an intensely personal experience?

"Seeking to discover what can be known and how we can know it, I looked into my mind. There, past all the rules and ideas that I had been taught, all the facts that I had apprehended through study, and all the sensory information that I had acquired through my physical body, I found an entity which does all this apprehending, acquiring and experiencing: the entity which thinks: my self. This is the one thing that did not come from outside; the one thing of which I am sure. The entity which can think this must exist.
I am. Cool. Now, let's see how I can test other truths."

Sounds to me like an experiment we all ought to try. (I'm pretty sure he threw in the guff about God and perfection for benefit of the inquisitors.)
Serpent
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### Re: The logic of "Cogito ergo sum"

Outdated, but had to chime in...

Bad logic nothing, I think you're missing the main point (and the beauty) of Descartes discovery/epiphany/argument…

Descartes was simply trying to see if he could definitively prove that he or " I " actually exist (existence here basically just meaning an independent mind capable of producing deliberate thought).

He proves this by running a very specific thought experiment, the famous, divinely inspired, words "I am" or "I exist" (or whatever words or symbols you consider to refer to " I " as in self, and "existence" as in whatever you consider the opposite of non-existence).

I said beauty earlier because the two words are very unique. It’s possible a Parrot could be trained to say them, but to think the words for yourself, inside yourself, and to really understand, on any level, the profound depth of the ability to even have the thought itself, is what Descartes was talking about.

Ego doesn't really come into it yet at this stage because as a philosophers Descartes is speaking to the very core of a person, the self, the mind, the entire package you consider to be within the " I " part of " I am" (even if you consider “everything” to be a part of you)...

And the parts of the mind, be it ego or whatever, are more psychology (granted a branch of philosophy, but an entirely independent branch) and not what Descartes was talking about at all (in fact he was oblivious to it)

Yet, he goes on to show why its impossible that you don't exist while you are thinking the thought that you do because only a mind that has existence is capable of having the thought, to itself, "I exist".

He's really not claiming a whole lot past that in this argument, only that he can be assured at the very least that his mind does really exist... and he tries to show how nothing, no trickery or deceit, not even God himself, could change the truth of his argument/experiment.

It’s not the so simple as the function of thinking is the same as the function of existing, instead its the ability, the capacity really, to be able to create the deliberate thought "I exist" that has the ability to prove (to oneself and no one else) that your mind does in fact exist (and exists independently at that!)

So it's a two part-er:

1: capability or capacity to run his experiment (argument) in your head
2: while, and only while, your doing step 1, you can be 100% sure that you exist

The funny part is his formula doesn't grant existence to everyone, only those capable of running his little experiment.

It would blow Descartes mind to learn people still like to think about his thoughts
" DESCARTES BUMP "
zaq222

### Re: The logic of "Cogito ergo sum"

avanover wrote:Could someone tell me how Descartes came to the logical statement think()≡exist()├(think(self)├exist(self))? I.E. The function of thinking is equivalent to the function of existing therefore function think of "self" implies function exist of "self".

I think you totally miss the point of his reasoning.

Did you read the book? If so then it should be evident what he means by it.

If you did not read the book, well, philosophy is not twitter, you actually have to read more than one-liners to follow what someone is trying to say.

By the way a logical consequence (e.g. therefore) in predicate logic is not the same as the identity.
Venus

### Re: The logic of "Cogito ergo sum"

Descartes was a dualist who accepted the existence of a soul and his famous statement must be read in this context. For a monist who denies the existence of such an entity as a soul "I am therefore I think" makes a lot more sense. But still not enough.

Regards Leo
Obvious Leo

### Re: The logic of "Cogito ergo sum"

zaq222 wrote:Outdated, but had to chime in...

Bad logic nothing, I think you're missing the main point (and the beauty) of Descartes discovery/epiphany/argument…

Descartes was simply trying to see if he could definitively prove that he or " I " actually exist (existence here basically just meaning an independent mind capable of producing deliberate thought).

Time to go back and read the Discourse on Method, I think. Descartes explicitly states that dubito cogito ergo sum is the first principle of his philosophy, and beyond the reaches of Cartesian doubt. This despite all the inferences he had to make to arrive at it. Bad logic.

Lomax

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### Re: The logic of "Cogito ergo sum"

Lomax wrote:Time to go back and read the Discourse on Method, I think. Descartes explicitly states that dubito cogito ergo sum is the first principle of his philosophy, and beyond the reaches of Cartesian doubt. This despite all the inferences he had to make to arrive at it. Bad logic.

I feel like your making Descartes argument into an ideology and then condemning his entire philosophy as logically unsound. (and worse, self-condemning).

Are you seeing some sort of doubt-able perception left unexamined between the self, the mind, and the thought itself?

What inferences exactly did he have to sneak by to arrive at it (his first philosophy)?

"First philosophy" would mean that the doubt must end somewhere if there is any certainty to be had in the world and "OMG, i think i discovered the spot" - Descartes

Are you doubting the validity of his statement in light of the logical means, or just the means he uses to get there?

Plenty of doubt still exists if you feel like you need to use it to later logically justify his momentary "certainty of existence" anytime your not running his thought experiment (since during the thought experiment itself you no longer need the doubt)
zaq222

### Re: The logic of "Cogito ergo sum"

zaq222 wrote:
Lomax wrote:Time to go back and read the Discourse on Method, I think. Descartes explicitly states that dubito cogito ergo sum is the first principle of his philosophy, and beyond the reaches of Cartesian doubt. This despite all the inferences he had to make to arrive at it. Bad logic.

I feel like your making Descartes argument into an ideology and then condemning his entire philosophy as logically unsound. (and worse, self-condemning).

Are you seeing some sort of doubt-able perception left unexamined between the self, the mind, and the thought itself?

What inferences exactly did he have to sneak by to arrive at it (his first philosophy)?

"First philosophy" would mean that the doubt must end somewhere if there is any certainty to be had in the world and "OMG, i think i discovered the spot" - Descartes

Are you doubting the validity of his statement in light of the logical means, or just the means he uses to get there?

Plenty of doubt still exists if you feel like you need to use it to later logically justify his momentary "certainty of existence" anytime your not running his thought experiment (since during the thought experiment itself you no longer need the doubt)

Lomax will have a better response, but you are over-reacting, I think. You are providing an argument not for the purpose of defending the logic of "Cogito ergo sum", but rather for a methodology (though I might be wrong even here). I don't think he was trying to pour cold-water over Descartes in whatever you take to be his positive influence -- rather I think he is pointing out that the logic of this famous dictum isn't correctly stated in the form it is expressed -- namely that from "I doubt" it therefore logically follows that "I exist". The 'ergo' is not to be taken in its logical sense if you are going to defend it.

James
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