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Church’s Thesis and Hume’s Problem: Justification as Performance. Kevin T. Kelly Department of Philosophy Carnegie Mellon University kk3n@andrew.cmu.edu. Further Reading.
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Church’s Thesis and Hume’s Problem:Justification as Performance Kevin T. Kelly Department of Philosophy Carnegie Mellon University kk3n@andrew.cmu.edu
Further Reading • (With C. Glymour) “Why You'll Never Know Whether Roger Penroseis a Computer”,Behavioral and Brain Sciences, 13: 1990. • The Logic of Reliable Inquiry, Oxford: Oxford University Press, 1996. • (with O. Schulte)“Church's Thesis and Hume's Problem,” in Logic and Scientific Methods, M. L. Dalla Chiara, et al., eds. Dordrecht: Kluwer, 1997. • (with O. Schulte and C. Juhl)“Learning Theory and the Philosophy of Science”,Philosophy of Science 64: 1997. • “The Logic of Success”, British Journal for the Philosophy of Science, 51:2000. • “Uncomputability: The Problem of Induction Internalized,” Theoretical Computer Science 317: 2004. • Computability and Learnibility, Textbook manuscript, 2005.
Classical Excuse Unbounded experience Completed analysis Rational Animal ?? Rational ? Always black? Reason Observation
But Maybe… Unbounded experience Unbounded analysis ?? ?? Rational ? Always black? Never white? Reason Observation
Kant 3 2 Unbounded experience 3 4 5 temporal intuition ?? Always black? 3+2 = 5 ? Never white? Intuition Observation
Oops! Unbounded experience spatial intuition ?? ?? Never cross? Always black? Never white? Intuition Observation
After Turing Unbounded computation Unbounded reality Input n ?? ?? Never halts? Always black? Never white? Computer Observation
.5 Verification as “Support” 1.0 Deductive verification Inductive verification
Paradigms Evolve • Objective support by evidence.
Paradigms Evolve… • Objective support by evidence. • Coherent personal opinion. • “Rational” update.
Paradigms Evolve… • Objective support by evidence. • Coherent personal opinion. • “Rational” update.
But Leading Metaphors Matter • Myopic • Bedrock = “rationality” intuitions • Success = being “rational” • Truth-finding performance deferred or ignored • Problem complexity ignored • Little resemblance to computability
Verification as Halting Conclusion Data
Verification as Halting Yes! Conclusion Data
Verification as Halting Conclusion Data
Verification as Halting Conclusion Data
Verification as Halting Bang! Conclusion Data
Verification as Halting Conclusion Data Can’t take it back.
Verifiability Yes! Conclusion true Conclusion false
Always green? Laws are Not Verifiable
Always green? Laws are Not Verifiable
Always green? Laws are Not Verifiable
Always green? Laws are Not Verifiable
Always green? Laws are Not Verifiable You must halt with “yes” if it’s true!
Always green? Laws are Not Verifiable You must halt with “yes” if it’s true!
Always green? Laws are Not Verifiable Yes!
Always green? Laws are Not Verifiable
Always green? Laws are Not Verifiable
Never shoots? A Purely Formal Problem
Never shoots? Analogy? I ain’t a’ shootin’, yeller belly!
Never shoots? Apparently Not Game’s up, J.R.! Yer program’s showin’! 666
Never shoots? 666 Apparently Not Now shaddup! I’m calculatin’ a-preeorey-like what yer gonna do.
Never shoots? Never shoots? 666 Apparently Not ?!!! 21456 23455
Never shoots? Never shoots? 666 But Then Again… I got it! Two kin play that opry oary game! 21456 23455
Never shoots? Never shoots? 666 21456 23455 21456 23455 But Then Again… I won’t shoot ‘til I see him shoot in this here opry oary sim-yooo-laytion! 666
Never shoots? Never shoots? 666 21456 23455 21456 23455 But Then Again… 666 I ain’t a’ shootin’.
Never shoots? Never shoots? 666 21456 23455 But Then Again… 666 I still ain’t a’ shootin’. 21456 23455
Never shoots? Never shoots? 666 21456 23455 But Then Again… 666 You check that there opry oary all you want… 21456 23455
Never shoots? Never shoots? 666 But Then Again… 666 21456 23455 An’ all you’ll see is I ain’t a-shootin’ 21456 23455
Never shoots? Never shoots? 666 But Then Again… Aw, shucks, J.R. I reckon You ain’t never gonna shoot. 666 21456 23455 Aw, shucks, J.R. I reckon you ain’t never gonna shoot. 21456 23455
Never shoots? Never shoots? 666 23455 23455 But Then Again… 666 Bang!
Never shoots? Never shoots? 666 23455 But Then Again… 666 23455