II XVII
Question/answer/Hintikka: the key to a theory of questions and answers lies in the relation of a question to its exhaustive answer.
Epistemic Logic: epistemic logic provides the solution.
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Epistemic logic.
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II 18
Questions/answers/Hintikka: the most important application of epistemic logic is a theory of question and answer. E.g.:
(1.1) Who lives here?
Is constructed as:
(1.2) Make that I know who lives here.
II 19
Answer/Hintikka: problem: when does a reply d on a W-question fulfill its purpose? Of course, if it makes the desideratum:
(1.3) "I know who lives here" true.
But what does the answer "d" do? Obviously:
(1.4) I know d lives here.
Answer/Hintikka: the problem is when (1.4.) implies (1.3).
Logical Form: the logical form of (1.3) and (1.4) is
(1.5) (Ex) {I} K (x lives here)
and
(1.6) {I} K (d lives here).
Epistemic Logic/response/quantifier/operator/Hintikka: that is, the operational problem is when (1.6) implies (1.5). It is about the interplay of quantifiers and epistemic operators.
II 19
Knowledge/w-questions/knowing/Hintikka: the right treatment is ensured by a series of steps.
II 20
(i)
Cross-World Identity/Hintikka: cross-world identity must be assumed as solved, so that we can use our quantifiers.
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Cross world identity.
World Line/Hintikka: world lines should connect the counterparts of an individual in different worlds.
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World lines.
If we have a web of world lines (in relation to a subject of knowledge), we have truth conditions for quantified sentences in an epistemic logic of the 1st level.
Truths Conditions: the truth conditions solve Quine's problem here ((s) of the cross-world identity) or transform them into problems how the world lines are to be drawn.
(ii)
Individual Area/individual/existence/possible worlds/Hintikka: it cannot be assumed that the same individuals exist in all models.
When we speak of z as an element of the actual world, we must assume that it exists in this world, so that it has a bona fide value of the quantifiers, which also applies, among others, in the actual world.
II 98
W-questions/who/what/where/Hintikka: thesis: w-questions are nothing but quantified phrases.
II 99
Logical Form:
(1) John knows who the Prime Minister of Norway is.
As a that-construction:
(2) (Ex) John knows that (the Prime Minister of Norway = x) (= de dicto).
Problem: you have to specify the domain of the individual that the variable "x" passes ((s) quotation marks from Hintikka).
II 102
W-Questions/non-existence/Hintikka: variant: problem:
(7) John knows that Homer did not exist.
That is, in any epistemically possible world of John, Homer does not exist. This implies that it makes sense to ask for existence.
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Non-existence.
Uniqueness/existence/Hintikka: i.e. we must distinguish between the existence and the uniqueness (determinateness) of an individual.
Non-existence/Hintikka: non-existence does not make the identity of the individual unknown.