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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Cogito, ergo sum | 3/5 | https://en.wikipedia.org/wiki/Cogito,_ergo_sum | reference | science, encyclopedia | 2026-05-05T13:43:56.776204+00:00 | kb-cron |
There are three important notes to keep in mind here. First, he claims only the certainty of his own existence from the first-person point of view — he has not proved the existence of other minds at this point. This is something that has to be thought through by each of us for ourselves, as we follow the course of the meditations. Second, he does not say that his existence is necessary; he says that if he thinks, then necessarily he exists (see the instantiation principle). Third, this proposition "I am, I exist" is held true not based on a deduction (as mentioned above) or on empirical induction but on the clarity and self-evidence of the proposition. Descartes does not use this first certainty, the cogito, as a foundation upon which to build further knowledge; rather, it is the firm ground upon which he can stand as he works to discover further truths. As he puts it:
Archimedes used to demand just one firm and immovable point in order to shift the entire earth; so I too can hope for great things if I manage to find just one thing, however slight, that is certain and unshakable. (AT VII 24; CSM II 16) According to many Descartes specialists, including Étienne Gilson, the goal of Descartes in establishing this first truth is to demonstrate the capacity of his criterion — the immediate clarity and distinctiveness of self-evident propositions — to establish true and justified propositions despite having adopted a method of generalized doubt. As a consequence of this demonstration, Descartes considers science and mathematics to be justified to the extent that their proposals are established on a similarly immediate clarity, distinctiveness, and self-evidence that presents itself to the mind. The originality of Descartes's thinking, therefore, is not so much in expressing the cogito—a feat accomplished by other predecessors, as we shall see—but on using the cogito as demonstrating the most fundamental epistemological principle, that science and mathematics are justified by relying on clarity, distinctiveness, and self-evidence. Baruch Spinoza in "Principia philosophiae cartesianae" at its Prolegomenon identified "cogito ergo sum" the "ego sum cogitans" (I am a thinking being) as the thinking substance with his ontological interpretation.
== Predecessors == Although the idea expressed in cogito, ergo sum is widely attributed to Descartes, he was not the first to mention it. In the late sixth or early fifth century BC, Parmenides is quoted as saying "For to be aware and to be are the same". (Fragment B3) Plato spoke about the "knowledge of knowledge" (Greek: νόησις νοήσεως, nóesis noéseos) and Aristotle explained the idea saying "whenever we perceive, we are conscious that we perceive, and whenever we think, we are conscious that we think, and to be conscious that we are perceiving or thinking is to be conscious that we exist" (Nicomachean Ethics, 1170a 25 ff.) The Cartesian statement was interpreted to be an Aristotelian syllogism where the premise that all thinkers are also beings is not made explicit. In the early fifth century AD, Augustine of Hippo in De Civitate Dei (book XI, 26) affirmed his certain knowledge of his own existence, and added: "So far as these truths are concerned, I do not at all fear the arguments of the Academics when they say, What if you are mistaken? For if I am mistaken, I exist." This formulation (si fallor, sum) is sometimes called the Augustinian cogito. In 1640, Descartes wrote to thank Andreas Colvius (a friend of Descartes's mentor, Isaac Beeckman) for drawing his attention to Augustine:
I am obliged to you for drawing my attention to the passage of St Augustine relevant to my I am thinking, therefore I exist. I went today to the library of this town to read it, and I do indeed find that he does use it to prove the certainty of our existence. He goes on to show that there is a certain likeness of the Trinity in us, in that we exist, we know that we exist, and we love the existence and the knowledge we have. I, on the other hand, use the argument to show that this I which is thinking is an immaterial substance with no bodily element. These are two very different things. In itself it is such a simple and natural thing to infer that one exists from the fact that one is doubting that it could have occurred to any writer. But I am very glad to find myself in agreement with St Augustine, if only to hush the little minds who have tried to find fault with the principle. Another predecessor was Avicenna's "Floating Man" thought experiment on human self-awareness and self-consciousness. The 8th century Hindu philosopher Adi Shankara wrote, in a similar fashion, that no one thinks 'I am not', arguing that one's existence cannot be doubted, as there must be someone there to doubt. Spanish philosopher Gómez Pereira in his 1554 work Antoniana Margarita, wrote "nosco me aliquid noscere, & quidquid noscit, est, ergo ego sum" ('I know that I know something, anyone who knows is, therefore I am').
== Critique ==