Originally posted by XanthosNZHe did recognize that he was wrong, instead of mocking him you should be praising him for having the intellectual honesty to do so (unlike many).
By discussed do you mean you insisted it was 50/50 and everyone else told you you were wrong and laughed in your face? Because that's what I read.
Originally posted by DoctorScribblesAre all propositions either true or false?
No, of course not. Only an idiot would think such a thing. To believe that, one would have to believe that all propostions are equally likely to be true or false, since all propositions are either true or false.
What about this proposition:
"This sentence is false"
Surely, this proposition is either both true and false, or neither true nor false, but not merely true, nor merely false.
Or would you contend that this is not a proposition?
7 edits
Originally posted by PawnokeyholeAll propositions are either true or false. No proposition is both true and false (except many made by lucifershammer and other religious zealots who haven't yet ironed out all of the incoherence in their belief systems but want to appear as if they have), nor is any proposition neither true nor false.
Are all propositions either true or false?
What about this proposition:
"This sentence is false"
Surely, this proposition is either both true and false, or neither true nor false, but not merely true, nor merely false.
Or would you contend that this is not a proposition?
If you hold that the example you provide is a proposition, it is a false one. That is because propositions assert that something is the case; that is, they claim that something is true. The example claims that it is both true, in virtue of being a proposition and thereby asserting itself, and false due to its text. That is, it is claiming that something is both true and false, a tautological falsehood. Therefore, the proposition is false. But it would be a fallacy to then assert that the proposition is true after negating its text, because that is only one clause of the conjunction asserted by the propostion, whose actual propositional content is "This proposition is true and this proposition is false."
Consider a non-self-referential example to follow the mechanics, like the proposition "Dogs have 10 legs," whose actual propositional content is "This proposition is true and Dogs have 10 legs." Here, we have another false proposition, because it is not the case that dogs have 10 legs. In this instance, negating the text of the proposition yields a true proposition: "Dogs do not have 10 legs." Why does the negation work here and not in the above case? Because here, both clauses of the conjunction are logically equivalent. In general, to deny (A and B) is to assert (Not-A or Not-B). In this example, Not-A is equivalent to Not-B, so we can just pick one, namely "Dogs do not have 10 legs" and validly assert it. In the self-referential example, Not-A and Not-B were not logically equivalent, so it is a fallacy to deduce Not-B from (Not-A or Not-B) in that example as we validly did in this one.
If you hold that it is not a proposition, then there is no issue.
Originally posted by DoctorScribbles"If dogs have 10 ten legs I am a monkey"
All propositions are either true or false. No proposition is both true and false (except many made by lucifershammer and other religious zealots who haven't yet ironed out all of the incoherence in their belief systems but want to appear as if they have), nor is any proposition neither true nor false.
If you hold that the example y ...[text shortened]... d in this one.
If you hold that it is not a proposition, then there is no issue.
Originally posted by DoctorScribblesYou've convinced me, as far as the liar paradox is concerned.
All propositions are either true or false. No proposition is both true and false (except many made by lucifershammer and other religious zealots who haven't yet ironed out all of the incoherence in their belief systems but want to appear as if they have), nor is any proposition neither true nor false.
If you hold that the example y ...[text shortened]... d in this one.
If you hold that it is not a proposition, then there is no issue.
What about propositions about the future? Do you regard them as already either true or false in the present? If so, does that mean that the future is entirely determined?
1 edit
Originally posted by PawnokeyholeI don't know. Ask bbarr. He already said he'd give some remarks about theories of knowledge and the relationship between propositions and reality, in light of how badly the topic was presented in the CRISIS Magazine article I cited a couple weeks ago.
You've convinced me, as far as the liar paradox is concerned.
What about propositions about the future? Do you regard them as already either true or false in the present? If so, does that mean that the future is entirely determined?
I suppose if I stick by my above remarks that all propositions have exactly one truth value, then I am committed to denying that claims about the future of the universe are proper propositions. I think this remains the case even when formulating the proposition within some sort of temporal logic framework.