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Single Idea 13368

[filed under theme 5. Theory of Logic / L. Paradox / 4. Paradoxes in Logic / b. König's paradox ]

Full Idea

König: there are indefinable ordinals, and the least indefinable ordinal has just been defined in that very phrase. (Recall that something is definable iff there is a (non-indexical) noun-phrase that refers to it).

Gist of Idea

The 'least indefinable ordinal' is defined by that very phrase

Source

Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §3)

Book Ref

-: 'Mind' [-], p.28


A Reaction

Priest makes great subsequent use of this one, but it feels like a card trick. 'Everything indefinable has now been defined' (by the subject of this sentence)? König, of course, does manage to pick out one particular object.


The 8 ideas from 'The Structure of Paradoxes of Self-Reference'

The least ordinal greater than the set of all ordinals is both one of them and not one of them [Priest,G]
The next set up in the hierarchy of sets seems to be both a member and not a member of it [Priest,G]
The 'least indefinable ordinal' is defined by that very phrase [Priest,G]
'x is a natural number definable in less than 19 words' leads to contradiction [Priest,G]
By diagonalization we can define a real number that isn't in the definable set of reals [Priest,G]
If you know that a sentence is not one of the known sentences, you know its truth [Priest,G]
There are Liar Pairs, and Liar Chains, which fit the same pattern as the basic Liar [Priest,G]
Typically, paradoxes are dealt with by dividing them into two groups, but the division is wrong [Priest,G]