Timeline for Existence as a Predicate
Current License: CC BY-SA 4.0
13 events
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| Dec 7, 2023 at 1:27 | history | edited | Hudjefa | CC BY-SA 4.0 |
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| Dec 7, 2023 at 0:39 | comment | added | Hudjefa | @MauroALLEGRANZA, Descartes' cogito can be formalized in sentential logic as T (cogito) --> E (sum). This conditional should become Ax(Tx --> Px) where Px = sum = I exist = an existence predicate. The issue is to claim (say) John exists, I have to say Ex(x = J). Should I then translate the sentential logic statement for the cogito as Td --> Ex(x = d) That would result (combined with the premise Td = Descartes thinks) in the conclusion Ex(x = d). Instantiating that means d = d (Descartes = Descartes). | |
| Dec 6, 2023 at 11:15 | comment | added | Mauro ALLEGRANZA | And the cogito is not the last step in the "proof" of the I existence, but is the first step in the proof of existence of God and the external world. | |
| Dec 6, 2023 at 11:14 | comment | added | Mauro ALLEGRANZA | See the post Can Cogito, ergo sum be formalized?: the most reasonable reading of D's argument is that it is not an inference but an intuition. '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 recognizes it as something self-evident by a simple intuition of the mind. (Replies 2, AT 7:140).' " | |
| Dec 6, 2023 at 10:28 | comment | added | Bumble | Why are you trying to prove that Descartes exists? That is not the point of the cogito. The point is to establish indubitably that I exist. According to Descartes, I cannot coherently doubt my own existence since to do so would be to doubt that I am doubting. One may object as many have done that it is unreasonable to assume that I is a coherent concept. But I can easily doubt that Descartes exists, or anybody else for that matter. Descartes' purpose is to establish an indubitable starting point for his epistemology. | |
| Dec 6, 2023 at 10:01 | comment | added | Hudjefa | @Bumble, are you sure that "there have been [...] the cogito formally"? Per the rules of predicate logic, we may instantiate an existential claim e.g. Ex(Tx) means Ta (by EI rule, there are caveats), but in existential claims in predicate logic there's entanglement between esse (being) and property (predicate). We may however use existential generalization like so: Td = Descartes is thinking. Ergo, Ex(Tx) = There exists something that is thinking. Td contains, within it, the claim that Descartes exists. However, we can't infer that Descartes is that thinking thing. | |
| Dec 6, 2023 at 8:23 | comment | added | Bumble | There have been many attempts to formulate the cogito formally. It is not as straightforward as it seems. Your current suggestion is not good. The cogito can really only be expressed in the first person. It is supposed to be an indubitable proof that I exist since I cannot ccherently doubt that I doubt. | |
| Dec 6, 2023 at 6:26 | history | edited | Hudjefa | CC BY-SA 4.0 |
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| Dec 6, 2023 at 3:36 | vote | accept | Hudjefa | ||
| Dec 6, 2023 at 0:27 | answer | added | David Gudeman | timeline score: 2 | |
| Dec 5, 2023 at 19:52 | comment | added | Mauro ALLEGRANZA | See Free Logic for an approach. | |
| Dec 5, 2023 at 18:47 | comment | added | Kristian Berry | Perhaps this goes to show that existence should not be inferred as such. Alternatively, reasoning in which existence is inferred is circular (for better or worse). As far as Descartes goes, we might want to look more for a derivation, "I exist as a thinking substance," which is more contentious (but for sort-of-Kantian reasons is perhaps doable, though not to the effect that thought is the matter of said substance). | |
| Dec 5, 2023 at 18:39 | history | asked | Hudjefa | CC BY-SA 4.0 |