Frege puzzles? (English) Zbl 1178.03004

The author discusses some problems derived from Frege’s classic “Über Sinn und Bedeutung” (1892), often fused as “Frege puzzles”, all of them based on Frege’s discussion of the difference between \(a=a\) and \(a=b\). The author’s exclusive focus is on the first thirteen sentences of Frege’s paper, reprinted in translation in Note 1 (p.570). The first, metaphysical, puzzle concerns identity as a logical relation. The second, semantical, puzzle arises out of the expectation that if two sentences say the same thing they ought to be “cognitive-significance indiscernible” (p.558). The puzzle is discussed in the cases of proper names (“Cicero=Cicero” and “Cicero=Tully”), empty names, denoting expressions, and empty descriptions. The third puzzle is related to the theory of cognition. It concerns the question whether certain identity judgements are informative or not, referring to what the author calls “Frege’s Informativeness Theorem” (p.566): “(FIT) A true objectual identity judgment ‘that object=that object’ is informative iff I\(_1\) (that object) is distinct from I\(_2\) (that object)”. This theorem is said to be false based on the claim that informativeness is dependent of the background information given when the judgement is made. This and the other puzzles are no “genuine puzzles” as the author argues.


03A05 Philosophical and critical aspects of logic and foundations
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