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Ideas for 'Explaining Explanation', 'A Structural Account of Mathematics' and 'fragments/reports'

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5 ideas

5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic

9561	The mathematics of relations is entirely covered by ordered pairs [Chihara]
	Full Idea: Everything one needs to do with relations in mathematics can be done by taking a relation to be a set of ordered pairs. (Ordered triples etc. can be defined as order pairs, so that <x,y,z> is <x,<y,z>>).
	From: Charles Chihara (A Structural Account of Mathematics [2004], 07.2)
	A reaction: How do we distinguish 'I own my cat' from 'I love my cat'? Or 'I quite like my cat' from 'I adore my cat'? Nevertheless, this is an interesting starting point for a discussion of relations.

5. Theory of Logic / K. Features of Logics / 2. Consistency

9552	Sentences are consistent if they can all be true; for Frege it is that no contradiction can be deduced [Chihara]
	Full Idea: In first-order logic a set of sentences is 'consistent' iff there is an interpretation (or structure) in which the set of sentences is true. ..For Frege, though, a set of sentences is consistent if it is not possible to deduce a contradiction from it.
	From: Charles Chihara (A Structural Account of Mathematics [2004], 02.1)
	A reaction: The first approach seems positive, the second negative. Frege seems to have a higher standard, which is appealing, but the first one seems intuitively right. There is a possible world where this could work.

5. Theory of Logic / L. Paradox / 1. Paradox

6007	If you know your father, but don't recognise your father veiled, you know and don't know the same person [Eubulides, by Dancy,R]
	Full Idea: The 'undetected' or 'veiled' paradox of Eubulides says: if you know your father, and don't know the veiled person before you, but that person is your father, you both know and don't know the same person.
	From: report of Eubulides (fragments/reports [c.390 BCE]) by R.M. Dancy - Megarian School
	A reaction: Essentially an uninteresting equivocation on two senses of "know", but this paradox comes into its own when we try to give an account of how linguistic reference works. Frege's distinction of sense and reference tried to sort it out (Idea 4976).

5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox

6006	If you say truly that you are lying, you are lying [Eubulides, by Dancy,R]
	Full Idea: The liar paradox of Eubulides says 'if you state that you are lying, and state the truth, then you are lying'.
	From: report of Eubulides (fragments/reports [c.390 BCE]) by R.M. Dancy - Megarian School
	A reaction: (also Cic. Acad. 2.95) Don't say it, then. These kind of paradoxes of self-reference eventually lead to Russell's 'barber' paradox and his Theory of Types.

5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / b. The Heap paradox ('Sorites')

6008	Removing one grain doesn't destroy a heap, so a heap can't be destroyed [Eubulides, by Dancy,R]
	Full Idea: The 'sorites' paradox of Eubulides says: if you take one grain of sand from a heap (soros), what is left is still a heap; so no matter how many grains of sand you take one by one, the result is always a heap.
	From: report of Eubulides (fragments/reports [c.390 BCE]) by R.M. Dancy - Megarian School
	A reaction: (also Cic. Acad. 2.49) This is a very nice paradox, which goes to the heart of our bewilderment when we try to fully understand reality. It homes in on problems of identity, as best exemplified in the Ship of Theseus (Ideas 1212 + 1213).