Olaf L. Müller

Crispin Wright hat die bislang beste Rekonstruktion von Putnams Beweis gegen die skeptische Hypothese vom Gehirn im Tank vorgelegt. Aber selbst in Wrights Fassung hat der Beweis einen Mangel: Er wird mithilfe eines Prädikates wie z.B. "Tiger" geführt und funktioniert nur, wenn man sich darauf verlassen kann, dass es Tiger wirklich gibt. Aber die Skeptikerin bestreitet, über die Existenz von Tigern bescheid zu wissen. Das Problem lässt sich dadurch beheben, dass man den Beweis – statt mit dem extensionalen Begriff der Referenz (wie bei Wright) – mit Intensionen führt. Zudem sollte der Beweis transzendental laufen, also einzig und allein auf den sprachlichen Voraussetzungen beruhen, die auch die Skeptikerin zur Formulierung ihrer Tank-Hypothese benötigt. The best reconstruction of Putnam's brain-in-a-vat argument is due to Crispin Wright. But even Wright's version of the argument is not convincing. It employs predicates such as 'tiger' and reaches the conclusion only if we can rely upon the existence of tigers; and the skeptic disputes our knowledge regarding tigers. The problem is not insuperable: The argument must be run, not with the extensionalistic notion of reference (as in Wright's version), but with intensions. Furthermore, the argument should have a transcendental form; it should exclusively rely on conditions that are needed by the skeptic for formulating her own position.

The analytic/synthetic distinction can be conceived from two points of view: from within or from without; from the perspective of one's own language or from the perspective of the language of others. From without, the central question is which sentences of a foreign language are to be classified as analytic. From within, by contrast, the question concerning the synthetic and the analytic acquires a normative dimension: which sentences am I not permitted to reject—if I want to avoid talking nonsense? Both perspectives on analytic sentences do not mutually exclude but supplement and illuminate each other. In "Two Dogmas", Quine's criticism of the analytic/synthetic distinction comes from within, whereas in Word and Object, Quine repeats his earlier criticism from without. His criticism is directed against Carnap's views on our understanding of theoretical terms. I challenge Quine's criticism in both of its versions and provide two definitions for analyticity that are immune to Quine's arguments. Using the first of these definitions (the one from without) I try to show how it is possible to distinguish (genuine) belief revision from linguistic change—even in case of a scientific revolution.