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A"er	
 Posi*vism:	
 Whats	
 Le"?
no	
 statement	
 which	
 refers	
 to	
 a	
 reality	
 
transcending	
 the	
 limits	
 of	
 all	
 possible	
 
experience	
 can	
 possibly	
 have	
 any	
 literal	
 
signi鍖cance;	
 from	
 which	
 it	
 must	
 follow	
 
that	
 those	
 who	
 have	
 striven	
 to	
 describe	
 
such	
 a	
 reality	
 have	
 all	
 been	
 devoted	
 to	
 the	
 
produc*on	
 of	
 nonsense.	
 

                                  Alfred	
 Jules	
 Ayer,	
 
                The	
 Elimina*on	
 of	
 Metaphysics
Karl	
 Popper	
 
(1902	
 	
 1994)
Problem	
 No.	
 1:	
 
Veri鍖ca*on	
 is	
 too	
 strong	
 a	
 criterion.	
 

If	
 truth	
 value	
 requires	
 veri鍖ca*on,	
 then	
 
     some	
 proposi*ons	
 can	
 never	
 be	
 
     considered	
 conclusively	
 true.
All	
 sheep	
 are	
 white.
All	
 sheep	
 are	
 white.
All	
 sheep	
 are	
 white.
veri鍖ca*on	
 




Moritz	
 Schlick	
 


                         falsi鍖ca*on	
 
                                           Karl	
 Popper
A.	
 J.	
 Ayer	
 
(1910	
 	
 1989)
strong	
 veri鍖ability:	
 veri鍖ca*on	
 that	
 
makes	
 the	
 truth	
 value	
 of	
 a	
 proposi*on	
 
certain	
 


weak	
 veri鍖ability:	
 veri鍖ca*on	
 that	
 
makes	
 the	
 truth	
 value	
 of	
 a	
 proposi*on	
 
probable
Most	
 sheep	
 are	
 white.
Problem	
 No.	
 2:	
 
          The	
 Problem	
 of	
 Induc*on	
 

induc5ve	
 reasoning:	
 extrac*ng	
 a	
 
  generaliza*on	
 from	
 speci鍖c	
 facts	
 or	
 
  cases.
induc*ve	
 reasoning	
 

1. In	
 the	
 past,	
 most	
 sheep	
 have	
 
    been	
 white.	
 
2. Today,	
 most	
 sheep	
 are	
 white.	
 
3. Therefore,	
 in	
 the	
 future	
 most	
 
    sheep	
 will	
 probably	
 be	
 white.
induc*ve	
 reasoning	
 

1. In	
 the	
 past,	
 the	
 future	
 has	
 
    resembled	
 the	
 past.	
 
2. Today,	
 the	
 future	
 resembles	
 
    the	
 past.	
 
3. Therefore,	
 in	
 the	
 future,	
 the	
 
    future	
 will	
 probably	
 resemble	
 
    the	
 past.
Kurt	
 G旦del	
 
(1906	
 	
 1978)
G旦dels	
 First	
 Incompleteness	
 Theorem	
 	
 
Any	
 e鍖ec5vely	
 generated	
 theory	
 capable	
 of	
 
      expressing	
 elementary	
 arithme5c	
 cannot	
 be	
 
      both	
 consistent	
 and	
 complete.	
 
	
 In	
 par5cular,	
 for	
 any	
 consistent,	
 e鍖ec5vely	
 
      generated	
 formal	
 theory	
 that	
 proves	
 certain	
 
      basic	
 arithme5c	
 truths,	
 there	
 is	
 an	
 
      arithme5cal	
 statement	
 that	
 is	
 true,	
 but	
 not	
 
      provable	
 in	
 the	
 theory.
In	
 other	
 words.	
 
An	
 arithme*c	
 system,	
 for	
 instance	
 a	
 鍖nite	
 set	
 of	
 
  axioms,	
 cannot	
 be	
 BOTH	
 consistent	
 and	
 
  complete.
where.	
 
Consistent	
 >	
 contains	
 no	
 logical/mathema*cal	
 
  contradic*ons	
 
Complete	
 >	
 describes	
 all	
 possible	
 logical/
  mathema*cal	
 statements.
In	
 other	
 words.	
 
there	
 is	
 an	
 arithme*c	
 statement	
 that	
 is	
 true,	
 
 but	
 not	
 provable	
 by	
 the	
 theory.	
 




Finite	
 lists	
 of	
 axioms	
 cannot	
 describe	
 a	
 system	
 
  where	
 all	
 statements	
 are	
 shown	
 to	
 be	
 true/
  false.
What	
 does	
 that	
 mean	
 for	
 ra*onalism?
Logical	
 systems	
 can	
 not	
 be	
 universal	
 
            systems	
 of	
 thought.
which	
 is	
 one	
 descrip*on	
 of:	
 



     Modernism
Things	
 fall	
 apart;	
 the	
 center	
 cannot	
 hold;	
 
Mere	
 anarchy	
 is	
 loosed	
 upon	
 the	
 world	
 	
 


William	
 Butler	
 Yeats,	
  The	
 Second	
 Coming
Did	
 you	
 love	
 your	
 
father?	
 

Yes.	
 

Prove	
 it.

More Related Content

Modernism Science and Uncertainty

  • 2. no statement which refers to a reality transcending the limits of all possible experience can possibly have any literal signi鍖cance; from which it must follow that those who have striven to describe such a reality have all been devoted to the produc*on of nonsense. Alfred Jules Ayer, The Elimina*on of Metaphysics
  • 4. Problem No. 1: Veri鍖ca*on is too strong a criterion. If truth value requires veri鍖ca*on, then some proposi*ons can never be considered conclusively true.
  • 5. All sheep are white.
  • 6. All sheep are white.
  • 7. All sheep are white.
  • 8. veri鍖ca*on Moritz Schlick falsi鍖ca*on Karl Popper
  • 9. A. J. Ayer (1910 1989)
  • 10. strong veri鍖ability: veri鍖ca*on that makes the truth value of a proposi*on certain weak veri鍖ability: veri鍖ca*on that makes the truth value of a proposi*on probable
  • 11. Most sheep are white.
  • 12. Problem No. 2: The Problem of Induc*on induc5ve reasoning: extrac*ng a generaliza*on from speci鍖c facts or cases.
  • 13. induc*ve reasoning 1. In the past, most sheep have been white. 2. Today, most sheep are white. 3. Therefore, in the future most sheep will probably be white.
  • 14. induc*ve reasoning 1. In the past, the future has resembled the past. 2. Today, the future resembles the past. 3. Therefore, in the future, the future will probably resemble the past.
  • 16. G旦dels First Incompleteness Theorem Any e鍖ec5vely generated theory capable of expressing elementary arithme5c cannot be both consistent and complete. In par5cular, for any consistent, e鍖ec5vely generated formal theory that proves certain basic arithme5c truths, there is an arithme5cal statement that is true, but not provable in the theory.
  • 17. In other words. An arithme*c system, for instance a 鍖nite set of axioms, cannot be BOTH consistent and complete.
  • 18. where. Consistent > contains no logical/mathema*cal contradic*ons Complete > describes all possible logical/ mathema*cal statements.
  • 19. In other words. there is an arithme*c statement that is true, but not provable by the theory. Finite lists of axioms cannot describe a system where all statements are shown to be true/ false.
  • 20. What does that mean for ra*onalism?
  • 21. Logical systems can not be universal systems of thought.
  • 22. which is one descrip*on of: Modernism
  • 23. Things fall apart; the center cannot hold; Mere anarchy is loosed upon the world William Butler Yeats, The Second Coming
  • 24. Did you love your father? Yes. Prove it.