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With regards to 2), there's a difference between trying to find an answer to a single yes/no question, and trying to find a general method for solving an infini

With regards to 2), there's a difference between trying to find an answer to a single yes/no question, and trying to find a general method for solving an infinite class of such questions. If a single yes/no question is clearly stated, then it does have an answer. This just a tautology - that's what it means to be clearly stated. For example, does there exist integers x, y, and z such that x^3 + y^3 + z^3 = 33? No one knows, but at least the question is clearly stated. The answer is definitely yes or no. More generally, x^3 + y^3 + z^3 = 33 is an example of a Diophantine equation (an equation between multivariate polynomials with integer coefficients and integer variables). Suppose we are not so interested in this particular equation, but instead want to find an algorithm that can always tell if a Diophantine equation has a solution. This kind of question might not have a solution, since such an algorithm might not exists. And in fact, it doesn't (Hilbert's tenth problem).

JadeNB 11y ago
> If a single yes/no question is clearly stated, then it does have an answer. Without having to reach for fancy counterexamples, how about the Empedoclean "Is the answer to this question 'no'?"?
- conceit 11y ago
  Simple answer on the metalevel: It's not clearly stated, because it's self referential. It's not a question by the GP's standards.
  - JadeNB 11y ago
    Well, to be sure, if the definition of 'clearly stated' is made to exclude counterexamples to the assertion, then there are no counterexamples. :-) I don't think many people would include 'not self referential' in the definition of 'clearly stated'; for example, "is this question more than eight words long?" is pretty clear.
    - MrManatee 11y ago
      To put my words in context, I was thinking about mathematical questions, such as "does there exist a curve that goes through every point in a square?". Everyone has some kind of intuitive understanding of what's a "curve", but mathematicians need a precise definition in order to make this question clear enough for mathematical study. (There is such a curve: the Hilbert curve.) It's not at all easy to recognize when a question is stated "clearly enough", and your questions provide an excellent example of this. The question "is this question more than eight words long?" refers to question itself (as a string), and in general, this kind of self-reference is perfectly harmless. The question "Is the answer to this question 'no'?" refers to its own answer, and this kind of self-reference is potentially problematic.
  - JadeNB 11y ago
    Also, it occurs to me that the self reference can be avoided by an epistemologically insignificant dodge: "Are you about to say 'no'?" (This dodge is, I admit, a little dodgy; it admits things like "I wasn't planning to" as a perfectly sound answer. However, I'm taking it as read that we understand all questions as yes / no questions.)
    - conceit 11y ago
      Implicitly, the "no" references the answer to the question itself, hence it's still selfreferential. In other words, the fallacy is to assume the following response was fixed to be an answer to the question. If I answered "no" it would be obvious that i wasn't planning to say "no" prior ("about") to the question. There is just no context in which the question would make sense the way you suggest. It's non-sense.

JadeNB 11y ago

> If a single yes/no question is clearly stated, then it does have an answer. Without having to reach for fancy counterexamples, how about the Empedoclean "Is the answer to this question 'no'?"?

conceit 11y ago
Simple answer on the metalevel: It's not clearly stated, because it's self referential. It's not a question by the GP's standards.
- JadeNB 11y ago
  Well, to be sure, if the definition of 'clearly stated' is made to exclude counterexamples to the assertion, then there are no counterexamples. :-) I don't think many people would include 'not self referential' in the definition of 'clearly stated'; for example, "is this question more than eight words long?" is pretty clear.
  - MrManatee 11y ago
    To put my words in context, I was thinking about mathematical questions, such as "does there exist a curve that goes through every point in a square?". Everyone has some kind of intuitive understanding of what's a "curve", but mathematicians need a precise definition in order to make this question clear enough for mathematical study. (There is such a curve: the Hilbert curve.) It's not at all easy to recognize when a question is stated "clearly enough", and your questions provide an excellent example of this. The question "is this question more than eight words long?" refers to question itself (as a string), and in general, this kind of self-reference is perfectly harmless. The question "Is the answer to this question 'no'?" refers to its own answer, and this kind of self-reference is potentially problematic.
- JadeNB 11y ago
  Also, it occurs to me that the self reference can be avoided by an epistemologically insignificant dodge: "Are you about to say 'no'?" (This dodge is, I admit, a little dodgy; it admits things like "I wasn't planning to" as a perfectly sound answer. However, I'm taking it as read that we understand all questions as yes / no questions.)
  - conceit 11y ago
    Implicitly, the "no" references the answer to the question itself, hence it's still selfreferential. In other words, the fallacy is to assume the following response was fixed to be an answer to the question. If I answered "no" it would be obvious that i wasn't planning to say "no" prior ("about") to the question. There is just no context in which the question would make sense the way you suggest. It's non-sense.