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Uniqueness condition/W-questions/response/Hintikka: the condition that something is a complete and unambiguous answer to a who-question (ambiguous, see above) is that (8) must imply (7):
(6) Who is the man over there?
(7) I know who the man is over there
E.g. it is Sir Norman Brook.
(8) I know that the man there is Sir Norman Brook.
Problem: the step from (8) to (7) is that of an existential generalization (EG).
Problem: We need an additional premise. E.g.
(13) (Ex) Ki (Sir Norman Brook = x).
(Non-mirrored quantifier, perceptually)
"I know who Norman Brook is."
Answer/Hintikka: what counts as a conclusive answer? E.g. Suppose someone responds "d". This is only conclusive if it provides the desired information, i.e. it makes it possible to tell the other truthfully:
(5) I know that d has killed Ackroyd.
Definition conclusive/conclusive answer/Hintikka: an answer is conclusive iff. (5) implies (4), for example,
(5) I know that d has killed Ackroyd.
(4) (Ex) I know that (x killed Ackroyd).
Problem: normally the implication is valid, but it can be because "d" (on different occasions) does not refer to the same person.
Knowledge/logical form: my knowledge that one or the other killed Ackroyd means that I have enough information...
... to exclude worlds (event developments), where one or the other (!) did not kill Ackroyd.
Additional premises: I still need the information that one and the same person is the murderer in all my knowledge worlds. That is, that d takes out the same individual in all the worlds. That is, that there is an individual x such that in all these worlds d = x.
(6) (Ex) I know that (d = x).
This only provides a conclusive answer.
(7) I know who is d.
N.B.: this criterion can be generalized.
Question/Answer/Hintikka: Problems that have not been solved yet:
(i) in addition to searching for a particular piece of information, the question implies restrictions on possible answers.
(ii) the problem of logical omniscience remains.
(iii) (1) can be expressed in other words:
(8) (x) (x killed Ackroyd > (Ez) (z = x & I know that (z killed Ackroyd)
((s) universal quantification!)
Everyday translation: i.e. the speaker does not only want to be aware of the identity of exactly one person who killed Ackroyd, but of all persons who ((s) killed Ackroyd).
(iv) What are the conditions in the case of complex questions?
(V) there are good answers that do not meet the criterion of coherence. How can partial information be defined which is provided in such cases?
(vi) Representations such as (4) and (8) require that quantifiers and epistemic operators (e.g., "I know that") are transitive from each other so that they can be put into a linear order. Can this fail?
Problem: that a question can only be answered if the questioner already knows the answer.
Solution/Hintikka: the "already" is deceptive: it is part of the answer to provide the accompanying information, so that the questioner can say afterwards truthfully,
(13) (Ex) I know that (= x)
Answer/Hintikka: a W-question has two functions:
A) to answer the question
B) to provide supplementary information showing that the reply itself is conclusive.
N.B.: i.e. that the questioner knows what the answer expression refers to after the answer has been given.
Questions/Answers/Hintikka: Thesis: the semantics of questions and answers is fundamentally different from the semantics for (normal) isolated sentences.
Additional Construction/Individuals/Introduction/Menon/Hintikka: The Menon Dialogue shows how new individuals (or constructions) are introduced into the discourse. Here: e.g. extension of a smaller square to a double the size._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution.
Jaakko and Merrill B. Hintikka
The Logic of Epistemology and the Epistemology of Logic Dordrecht 1989
J. Hintikka/M. B. Hintikka
Untersuchungen zu Wittgenstein Frankfurt 1996