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Single Idea 10048

[filed under theme 5. Theory of Logic / A. Overview of Logic / 4. Pure Logic ]

Full Idea

No objective grounds are known to me which permit us to draw a sharp boundary between the two groups of terms, the logical and the non-logical.

Gist of Idea

There is no clear boundary between the logical and the non-logical

Source

Alfred Tarski (works [1936]), quoted by Alan Musgrave - Logicism Revisited §3

Book Ref

-: 'British Soc for the Philosophy of Science' [-], p.103


A Reaction

Musgrave is pointing out that this is bad news if you want to 'reduce' something like arithmetic to logic. 'Logic' is a vague object.


The 6 ideas from 'works'

In everyday language, truth seems indefinable, inconsistent, and illogical [Tarski]
Tarski thought axiomatic truth was too contingent, and in danger of inconsistencies [Tarski, by Davidson]
There is no clear boundary between the logical and the non-logical [Tarski]
Logical consequence is when in any model in which the premises are true, the conclusion is true [Tarski, by Beall/Restall]
Logical consequence: true premises give true conclusions under all interpretations [Tarski, by Hodges,W]
Tarski improved Hilbert's geometry axioms, and without set-theory [Tarski, by Feferman/Feferman]