Olaf Müller: Gehirn im Tank

Olaf Müller: Gehirn im Tank

“Seit den Matrix-Filmen streiten sich Informatiker und Laien, ob alle unsere Erlebnisse und Eindrücke der Welt vollständig auf Computersimulation beruhen könnten. Olaf L. Müller behauptet, dass der Streit längst entschieden ist: durch einen völlig neuartigen Beweis, dessen geniale Grundidee der Harvard-Philosoph Hilary Putnam im Jahr 1981 publiziert hat. Wie sich zweifelsfrei demonstrieren lässt, ist die Welt garantiert keine Illusion aus dem Simulationscomputer.”


Keith DeRose: Responding to Skepticism

Responding to Skepticism

  • 1. The Argument by Skeptical Hypothesis
  • 2. “Aw, Come On!”
  • 3. Moore’s Response
  • 4. The Response from Semantic Externalism
  • 5. Responses from Epistemic Externalism
  • 6. Relevant Alternatives and Denying Closure
  • 7. Contextualist Responses
  • 8. Concessive Responses

Introduction to Skepticism: A Contemporary Reader (Oxford UP, 1999)
Keith DeRose , Yale University

Peter Suber: Classical Skepticism

Peter Suber: Classical Skepticism – Issues and Problems

Peter Suber, Philosophy Department, Earlham College

“Skepticism” @ SEP


Skepticism @ Stanford Encyclopedia of Philosophy

Theory of Knowledge

Theory of Knowledge

Edmund Gettier: Is Justified True Belief Knowledge?

Much ado about contemporary skepticism has to do with a famously concise article Is Justified True Belief Knowledge? by Edmund L. Gettier that appeared in Analysis 23 (1963), pp. 121-123.

Thanks to the permission of the author and the efforts of Andrew Chrucky it is also available as a hypertext transcription at:

Various attempts have been made in recent years to state necessary and sufficient conditions for someone’s knowing a given proposition. The attempts have often been such that they can be stated in a form similar to the following:

a. S knows that P IFF
  • P is true,
  • S believes that P, and
  1. S is justified in believing that P.

For example, Chisholm has held that the following gives the necessary and sufficient conditions for knowledge:

b. S knows that P IFF
  • S accepts P,
  • S has adequate evidence for P, and
  1. P is true.

Ayer has stated the necessary and sufficient conditions for knowledge as follows:

c. S knows that P IFF
  • P is true,
  • S is sure that P is true, and
  1. S has the right to be sure that P is true.

I shall argue that (a) is false in that the conditions stated therein do not constitute a sufficient condition for the truth of the proposition that S knows that P. The same argument will show that (b) and (c) fail if ‘has adequate evidence for’ or ‘has the right to be sure that’ is substituted for ‘is justified in believing that’ throughout.

Some related resources: