If someone claim, logically, that the proposition is either true or false, and the middle between these two alternatives is raise, this is on the ontological level, which does not depend at all on human knowledge, beliefs and evidence. From this it turns out that those who follow the famous Polish logician Jan Łukasiewicz (1878-1956) method to the existence of three credibility values (truth, falsity, and indeterminacy) confuse existential and epistemological considerations. There are no indeterminacy issues of values. As for the epistemological level, the middle between them is not raiseable, as we may know that the proposition is true, and we may know that the proposition is false, and we may not know which value possesses it. Is his claim true or false or indeterminacy?
Propositional value
as known and as predicated of a subject is true, or otherwise false. In this case everything that falls within one's cognitive purview. Logically, knowledge is opposed to indeterminacy as what is known is known in form of determinate mode of being or other.
However, beyond Berkeley's 'esse est percipi' thesis, there are existents in their ontological rights, perhaps unknown by some subjects.
I think that the researcher is correct as against the thesis of the Polish logician.
Arguably there are at least some1 statements for which reference failure of the subject term will have the consequence that what is predicated of it cannot be either true or false. E.g. "Martha's brother is a doctor" in the case where Martha is an only child.
Similarly some questions will have neither a yes or a no answer. E.g "Do you still beat your wife?" in the case where you have no wife or else have one but have never beaten her.
We might adopt J. L. Austin's coinage and say that such statements and questions are "infelicitous".
________
1 Certain pragmatic contexts can nevertheless be envisaged which prevent this from being generalizable.
Thanks so much, Prof Karl, for your comment, in fact, the ambiguity arises from the language when the proposition contains future contingents Sentences. The philosophers refer to the work of Aristotle's argument " There will be a sea-battle tomorrow." This argument was represented the kernel of many-valued logic which started by Łukasiewicz's argument " "I shall be in Warsaw at noon 21 December of the next Year. ", after that Zadeh in 1965 introduced to us new extension for two Value {0,1} into closed interval [0,1] for many -valued degree membership. Of course, he borrowed from probability theory, the concept of a probability function, the fact that prediction of future events, depends on the facts of probability science. Next step later, in 1986 Atanassov adds new degree membership function which is called flashed degree membership, but its facts related induced from probability science. This paved the way for Smarandache to generalization the work of Łukasiewicz related to concept of indeterminacy as a degree of membership in 1995. In this respect, to approximate the idea, , if I claim that the world will be end in 2050 AD. Does the value of the truth - if there is a truth - depend on the knowledge we possess in order to make a judgment about it Without that knowledge, we don't have a reliable decision?
Adel Mohammed Al-Odhari
Yes, there are other avenues to a proposition being neither T nor F, and Aristotle's future contingents is one of them.
I don't believe in foreknowledge, but perhaps if a future-tensed proposition P is T or F at present we can say (1) we don't know which it is, (2) we can admit that such knowledge is impossible (because the relevant facts don't exist), and (3) say that at some future time we will be able to make a past-tensed statement Q, where Q says either that P was T or that P was F (except we couldn't have known which at the time). This would of course require complex formalization that I am not capable of, but at least indeterminacy seems avoidable1, unlike the situation with propositions involving the failure of a term to refer.
For the reliable decisions you're after, I agree that probability is the way to go, but probabilities are defeasible and notoriously difficult to assign.
________
1 We might still employ a notion of epistemic indeterminacy in some of our explanations in the metalanguage, but it needn't appear as a value in our truth-value assignments. However, infelicity in the case of reference failure is another matter
- Badges
- Science topic
- Similar topics
- Biological Science
- Bioecology
- Systems Ecology
- Landscape Ecology
- Connectivity