| 451 | Thinking implies existence, because thinking depends on it [Parmenides] |
| Full Idea: To think is the same as the thought that IT IS, for you will not find thinking without Being, on which it depends for its expression. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 2573 | To perceive or think is to be conscious of our existence [Aristotle] |
| Full Idea: To be conscious that we are perceiving or thinking is to be conscious of our existence (for we have seen that existence is sensation or thought). | |
| From: Aristotle (Nicomachean Ethics [c.334 BCE], 1170a32) | |
| A reaction: A lovely glimpse of Descartes' Cogito, which was made more explicit by Augustine. Is an animal (which presumably perceives) conscious of its existence? |
| 3912 | I must exist in order to be mistaken, so that even if I am mistaken, I can't be wrong about my own existence [Augustine] |
| Full Idea: Since therefore I must exist in order to be mistaken, then even if I am mistaken, there can be no doubt that I am not mistaken in my knowledge that I exist…. I know that I exist, and I also know that I know. | |
| From: Augustine (City of God [c.427], Ch.XI.26) | |
| A reaction: Fine, but the main problem is his over-confidence about a stable personal identity that does the thinking. |
| 3622 | The Cogito is not a syllogism but a self-evident intuition [Descartes] |
| Full Idea: When someone says 'I am thinking, therefore I am, or I exist', he does not deduce existence from thought by means of a syllogism, but recognises it as something self-evident by a simple intuition of the mind. | |
| From: René Descartes (Reply to Second Objections [1641], 140) |
| 24020 | We all see intuitively that we exist, where intuition is attentive, clear and distinct rational understanding [Descartes] |
| Full Idea: By intuition I mean the conception of an attentive mind, so distinct and clear that it has no doubt about what it understands, …a conception that is borne of the sole light of reason. Thus everyone can see intuitively that he exists. | |
| From: René Descartes (Rules for the Direction of the Mind [1628], 03) | |
| A reaction: By 'intuition' he means self-evident certainty, whereas my concept is of a judgement of which I am reasonably confident, but without sufficient grounds for certainty. This is an early assertion of the Cogito, with a clear statement of its grounding. |
| 24031 | When Socrates doubts, he know he doubts, and that truth is possible [Descartes] |
| Full Idea: If Socrates says he doubts everything, it necessarily follows that he at least understands that he doubts, and that he knows that something can be true or false: for these are notions that necessarily accompany doubt. | |
| From: René Descartes (Rules for the Direction of the Mind [1628], 12) | |
| A reaction: An early commitment to the Cogito. But note that the inescapable commitment is not just to his existence, but also to his own reasoning, and his own commitment, and to the possibility of truth. Many, many things are undeniable. |
| 3607 | In thinking everything else false, my own existence remains totally certain [Descartes] |
| Full Idea: While I decided to think that everything was false, it followed necessarily that I who thought thus must be something; the truth 'I think therefore I am' was so certain that the most extravagant scepticism could never shake it. | |
| From: René Descartes (A Discourse on Method [1637], §4.32) |
| 6929 | Modern philosophy set the self-conscious ego in place of God [Descartes, by Feuerbach] |
| Full Idea: Modern philosophy set the thinking being, the ego, and the self-conscious mind in the place of the merely ideated being, in place of God. | |
| From: report of René Descartes (Meditations [1641]) by Ludwig Feuerbach - Principles of Philosophy of the Future §37 | |
| A reaction: Descartes would be shocked by this interpretation, but God comes third in his logical priorities, after the existence of his ego, and its reliance on what is clear and distinct. |
| 3849 | "I think therefore I am" is the absolute truth of consciousness [Sartre on Descartes] |
| Full Idea: "I think therefore I am" is the absolute truth of consciousness as it attains to itself. | |
| From: comment on René Descartes (Meditations [1641], §2) by Jean-Paul Sartre - Existentialism and Humanism p.44 |
| 2258 | I must even exist if I am being deceived by something [Descartes] |
| Full Idea: Doubtless I exist if I persuade myself of something. But there is some powerful and cunning deceiver who is deliberately deceiving me. Then too there is no doubt that I exist, if he is deceiving me. | |
| From: René Descartes (Meditations [1641], §2.25) |
| 2259 | "I am, I exist" is necessarily true every time I utter it or conceive it in my mind [Descartes] |
| Full Idea: "I am, I exist" is necessarily true every time I utter it or conceive it in my mind. | |
| From: René Descartes (Meditations [1641], §2.25) |
| 3160 | The Cogito is a transcendental argument, not a piece of a priori knowledge [Rey on Descartes] |
| Full Idea: The Cogito is a transcendental argument; Descartes doesn't claim that it is a priori that he exists, but that any doubt or denial that he exists would presuppose his existence. | |
| From: comment on René Descartes (Meditations [1641], §2.26) by Georges Rey - Contemporary Philosophy of Mind 3.2.1 |
| 2260 | If I don't think, there is no reason to think that I exist [Descartes] |
| Full Idea: It could be that if I were to cease all thinking I would then utterly cease to exist. …I am therefore precisely nothing but a thinking thing; that is, a mind, or intellect, or understanding, or reason. | |
| From: René Descartes (Meditations [1641], §2.27) |
| 6914 | Descartes transformed 'God is thinkable, so he exists' into 'I think, so I exist' [Descartes, by Feuerbach] |
| Full Idea: Descartes transformed the proposition 'because God is thinkable, therefore he exists' into the proposition 'I think, therefore I am'. | |
| From: report of René Descartes (Meditations [1641], 2) by Ludwig Feuerbach - Principles of Philosophy of the Future §18 | |
| A reaction: This implies that Descartes' foundation is the Ontological Argument rather than the Cogito. It certainly shows how a priori synthetic thinking is basic in Descartes - that views of existence derive from pure thought. Was Descartes an idealist? |
| 4641 | In the Meditations version of the Cogito he says "I am; I exist", which avoids presenting it as an argument [Descartes, by Baggini /Fosl] |
| Full Idea: Descartes may have been aware of the danger of begging the question (in claiming "I think therefore I am") because in 'Meditations' he says "I am; I exist", which is not presented in the form of an argument. | |
| From: report of René Descartes (Meditations [1641], 2) by J Baggini / PS Fosl - The Philosopher's Toolkit §3.22 | |
| A reaction: Certainly the word 'therefore' cries out for a strict analysis of what is being inferred from what, but presenting the Cogito as a self-evident intuition for the 'natural light' has its own problems. |
| 3658 | Total doubt can't include your existence while doubting [Descartes] |
| Full Idea: He who decides to doubt everything cannot nevertheless doubt that he exists while he doubts. | |
| From: René Descartes (Principles of Philosophy [1646], Pref) |
| 5005 | I think, therefore I am, because for a thinking thing to not exist is a contradiction [Descartes] |
| Full Idea: There is a contradiction in conceiving that what thinks does not (at the same time as it thinks) exist. Hence this conclusion I think, therefore I am, is the first and most certain that occurs to one who philosophises in an orderly way. | |
| From: René Descartes (Principles of Philosophy [1646], I.07) | |
| A reaction: The classic statement of his argument. The significance here is that it seems to have the structure of an argument, as it involves 'philosophising', which leads to a 'contradiction', and hence to the famous conclusion. It is not just intuitive. |
| 5006 | 'Thought' is all our conscious awareness, including feeling as well as understanding [Descartes] |
| Full Idea: By the word 'thought' I understand everything we are conscious of as operating in us. And that is why not only understanding, willing, imagining, but also feeling, are here the same thing as thinking. | |
| From: René Descartes (Principles of Philosophy [1646], I.09) | |
| A reaction: There is a bit of tension here between Descartes' correct need to include feeling in thought for his Cogito argument, and his tendency to dismiss animal consciousness, on the grounds that they only sense things, and don't make judgements. |
| 12564 | I am as certain of the thing doubting, as I am of the doubt [Locke] |
| Full Idea: If I know I doubt, I have as certain a perception of the existence of the thing doubting, as of that thought which I call doubt. | |
| From: John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 4.09.03) | |
| A reaction: The challenge to this Lockean assertion of the Cogito is what he means by a 'thing', and what grounds he has for asserting the existence of the 'thing', as opposed to some vague assertion about whatever makes doubting possible. |
| 12905 | I cannot think my non-existence, nor exist without being myself [Leibniz] |
| Full Idea: I am assured that as long as I think, I am myself. For I cannot think that I do not exist, nor exist so that I be not myself. | |
| From: Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1686.05.13) | |
| A reaction: Elsewhere he qualifies the Cogito, but here he seems to straighforwardly endorse it. |
| 23659 | If someone denies that he is thinking when he is conscious of it, we can only laugh [Reid] |
| Full Idea: If any man could be found so frantic as to deny that he thinks, while he is conscious of it, I may wonder, I may laugh, or I may pity him, but I cannot reason the matter with him. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: An example of the influence of Descartes' Cogito running through all subsequent European philosophy. There remain the usual questions about personal identity which then arise, but Reid addresses those. |
| 15636 | The Cogito is at the very centre of the entire concern of modern philosophy [Hegel] |
| Full Idea: The proposition 'Cogito Ergo Sum' stands at the very centre, so to speak, of the entire concern of modern philosophy. | |
| From: Georg W.F.Hegel (Logic (Encyclopedia I) [1817], §64 Rem) | |
| A reaction: I distinguish two approaches to philosophy: the Parmenidean (which starts from the nature of being), and the Cartesian (which starts from the fact of consciousness). This remark confirms that Hegel is firmly in the latter school. |
| 15611 | I develop philosophical science from the simplest appearance of immediate consciousness [Hegel, by Hegel] |
| Full Idea: In my 'Phenomenology of Spirit' the procedure adopted was to begin from the first and simplest appearance of the spirit, from immediate consciousness, and to develop the dialectic right up to the standpoint of philosophical science. | |
| From: report of Georg W.F.Hegel (Phenomenology of Spirit [1807]) by Georg W.F.Hegel - Logic (Encyclopedia I) §25 Rem | |
| A reaction: I take metaphysics to be either Parmenidean (starting from Being) or Cartesian (starting from mind), and this (surprisingly, given his lengthy talk of Being) shows Hegel to be a quintessentially Cartesian philosopher. Aristotle is the great Parmenidean. |
| 4165 | Descartes found the true beginning of philosophy with the Cogito, in the consciousness of the individual [Schopenhauer] |
| Full Idea: By taking Cogito Ergo Sum as the only certainty, and by his provisionally regarding the existence of the world as problematical, the essential starting point of all philosophy was found, and its true focus in the subjective, the individual consciousness. | |
| From: Arthur Schopenhauer (The World as Will and Idea [1819], I Supp) | |
| A reaction: Some people think this was a disaster, not a triumph. Descartes could have doubted himself and accepted the world as his starting point. |
| 21220 | The physical given, unlike the mental given, could be non-existing [Husserl] |
| Full Idea: Anything physical which is given in person can be non-existing, no mental process which is given in person can be non-existing. | |
| From: Edmund Husserl (Ideas: intro to pure phenomenology [1913], II.2.046), quoted by Victor Velarde-Mayol - On Husserl 3.3.5 | |
| A reaction: This endorsement of Descartes shows how strong the influence of the Cogito remained in later continental philosophy. Phenomenology is a footnote to Descartes. |
| 5359 | Descartes showed that subjective things are the most certain [Russell] |
| Full Idea: By showing that subjective things are the most certain, Descartes performed a great service to philosophy. | |
| From: Bertrand Russell (Problems of Philosophy [1912], Ch. 2) | |
| A reaction: This praise comes from an empiricist, who has just said that 'sense-data' are the most certain things. I presume that animals are more certain of the world than they are of subjective things. In fact, probably on philosophers agree with Russell. |
| 21862 | Consciousness is based on 'I can', not on 'I think' [Merleau-Ponty] |
| Full Idea: Consciousness is in the first place not a matter of 'I think' but of 'I can'. | |
| From: Maurice Merleau-Ponty (Phenomenology of Perception [1945], p.159), quoted by Beth Lord - Spinoza's Ethics 2 'Sensation' | |
| A reaction: The point here (quoted during a discussion of Spinoza) is that you can't leave out the role of the body, which seems correct. |
| 3828 | Thinking must involve a self, not just an "it" [Searle] |
| Full Idea: We should not say "It thinks" in preference to "I think". If thinking is an active, voluntary process, there must be a self who thinks. | |
| From: John Searle (Rationality in Action [2001], Ch.3.IX) |
| 8221 | We cannot judge the Cogito. Must we begin? Must we start from certainty? Can 'I' relate to thought? [Deleuze/Guattari] |
| Full Idea: There is no point in wondering whether Descartes' Cogito is right or wrong. Is it necessary "to begin", and, if so, is it necessary to start from the point of view of a subjective certainty? Can thought be the verb of an I? There is no direct answer. | |
| From: G Deleuze / F Guattari (What is Philosophy? [1991], 1.1) | |
| A reaction: A nice first sentence for a work of philosophy would be "It is necessary to begin". Is the Cogito the only idea that is beyond judgement? I fear a slippery slope here, which would paralyse all of our judgements - and would therefore be ridiculous. |
| 3881 | In the Cogito argument consciousness develops into self-consciousness [Scruton] |
| Full Idea: In the course of the argument the first person has acquired a character; he is not merely conscious, but self-conscious. | |
| From: Roger Scruton (Modern Philosophy:introduction and survey [1994], 4) |