Timeline for Aristotle's Logic and Human Thought
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
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| May 24, 2019 at 13:32 | comment | added | Logikal | @speakpigeon, my point is deductive reasoning is useful because it CAN LEAD TO NEW KNOWLEDGE if done correctly. To people in math and those humans who think logic & math are identical you hear them Express to other humans that logic can't derive new information but only repeat what you put in or logic doesn't deal in truths. Well if TRUTH is in the definition of validity how is this possible? It is possible because someone misunderstood the concept!! Can you provide an example of an realistic argument that does not have empirical propositions speakpigeon? | |
| May 24, 2019 at 13:23 | comment | added | Logikal | @Speakpigon, only people into mathematics regurgitate logic is about validity. Validity has changed context & you dont seem to realize it. Validity used to imply that any correctly formed syllogism argument would hold regardless of the content matter aka subject content. If I can show the same form of argument with different subject matter the argument would still yield a TRUE conclusion. We would have objective knowledge necessarily. If I can change the truth value of the conclusion to FALSE depending on what we argue about your argument FORM CAN'T be correct.This is called a counterexample | |
| May 24, 2019 at 13:12 | comment | added | Logikal | @PeterJ, I would disagree that logic can't deal with TRUTH when my whole point was all syllogisms are to BE SOUND arguments. That means the premises must be true and the argument be valid. In this way we have a system of thought. Any other way we have a system that doesn't work 100 percent which is what validity used to imply. | |
| May 24, 2019 at 13:03 | comment | added | user20253 | @Speakpigeon - I have some sympathy with your comments and those of Logikal. I'd agree that logic cannot establish truth or 'what is the case', only truths relative to the axioms. I believe Aristotle notes this somewhere. My interest is not so much in syllogisms or other systems of proof as in the underlying logic on which these proofs depend, the RCP, LEM, LNC and so forth, and no doubt some of the confusion here is caused by my rather woolly question. . , | |
| May 24, 2019 at 9:20 | comment | added | Speakpigeon | Let us continue this discussion in chat. | |
| May 24, 2019 at 8:51 | comment | added | Speakpigeon | @Logikal Sorry if I misunderstood you but if I really did, then I still do. The question here is about Aristotelian logic and logic isn't about deciding whether empirical propositions, such as whether all swans are white, are true or false. It is about deciding whether a conclusion follows from the premises. Nothing else. The truth of empirical propositions, such as your example about time portals, is assessed entirely outside of logic. Logic has absolutely nothing to say about that. Nor does mathematics. There isn't much else to say on the subject. | |
| May 23, 2019 at 17:04 | comment | added | Logikal | @speakpigeon, again you err. The conclusion of a VALID ARGUMENT Is indeed necessary but it is impossible to have a valid argument with TRUE premises and a non true conclusion. This means the conclusion must be certain in the given circumstances. Again we circle about How do you know any x is true? What criteria would you accept if I state all black holes of a particular mass are objects that are time portals? If logic has nothing whatsoever to do with truth then why is TRUTH in the definition of validity? I am saying you should not be claiming something is logic if you misuse the terms. | |
| May 23, 2019 at 16:58 | comment | added | Logikal | @speakpigeon You are misunderstanding what I wrote. I did NOT SAY or Express logic is about the truth of the premises. I stayed that KNOWING the truth value of the premises is important & NOT telling other humans that all propositions are assumptions as Mathematical logic does. If the premises of a VALID argument are TRUE then the conclusion MUST ALSO be TRUE. The example you gave to refute me in your comment was not a VALID argument. | |
| May 23, 2019 at 16:51 | comment | added | Speakpigeon | @Logikal The conclusion of an argument is not said to be "certain" as you claim here. The truth of the conclusion is said to be necessary given the truth of the premises. The conclusion may well in fact be false. Socrates is a man; All men are immortal; Therefore, Socrates is immortal. Valid and yet false conclusion. Valid means here that if the premises were true, the conclusion would necessarily be true. Too bad the premises aren't true, though. | |
| May 23, 2019 at 16:47 | comment | added | Speakpigeon | @Logikal There's no part of logic that tells you how to decide whether particular premises are true or false. Not in mathematical logic, not in Aristotle's logic, not in the Stoics' logic, not in the Scholastics' logic. So, clearly, logic is not about the truth of your premises. You makes an argument? Fine, then you take responsibility for asserting the premises as true. Taking the responsibility means you answer questions like "How do you know the premises are true?". So, the truth of the premises is not decided by any method of logic. | |
| May 23, 2019 at 15:07 | comment | added | Logikal | Thank you for the reply. However the issue is still how do you know what is TRUE. If you say X is a fact in every case how do you know this in reality? I don't see how you can people in Mathematical logic can consistently tell other humans that logic is purely about form and NOT about truth when this same topic of TRUTH arises when the conclusion of a valid argument is stated to be a certain. How do you move from every proposition is an assumption but your valid argument conclusion is CERTAIN? This seems inconsistent no? It shows indeed logic does involve truth. | |
| May 23, 2019 at 14:48 | comment | added | Mauro ALLEGRANZA | "Deductive reasoning as Aristotle used the original purpose of what propositions are was to focus only on soundness - and not validity as Mathematical logic does." WRONG. See A's Topics (ref in my answer) : "Now a deduction is an argument in which, certain things being laid down, something other than these necessarily comes about through them. It is a demonstration, when the premisses from which the deduction starts are true and primitive." | |
| May 23, 2019 at 13:18 | comment | added | Logikal | Thanks for you interest. I wanted to write an answer that did not directly address how syllogisms work as did the Mathematical respondents did. There is a huge difference today in the same concepts & terms than let us say 60 years ago. Too many people define a logical term "proposition" amongst other terms incorrectly. This is because to those people all logic is logic and they are never told any distinctions -- until they meet someone like me. The whole idea of logic was What is now deemed EPISTEMOLOGY. people try to hide this fact. Logical form mattered but also content mattered. | |
| May 23, 2019 at 10:02 | comment | added | user20253 | Thanks for your thoughts and some interesting observations. | |
| May 22, 2019 at 21:05 | history | answered | Logikal | CC BY-SA 4.0 |