In Omniscience and Indexical Reference, Hector-Neri Castaneda formulates the following principle, which he designates (P): If a sentence of the form 'X knows that a person Y knows that . . .' formulates a true statement, then the person X knows the statement formulated by the clause filling the blank '. . .'. (Castaneda 1967a, 207).1 Thus, for example, Jones knows that Smith knows that 2 + 5 = 7 entails Jones knows that 2 + 5 = 7. In the present essay shall be attempting to demonstrate that situations such as Castaneda considers often take on an unexpected significance when viewed in the light of arguments pertaining to Searle's Chinese Room scenario. This significance is especially noteworthy given that it concerns the problem of the relationship between private knowledge and public knowledge (and, shall argue, by extension the problem)-a problem often considered by Castaneda and other researchers in his area. Indexicals and the Mind-Body Problem It is not hard to see why consideration of indexicals should eventually lead to consideration of the mental substance/physical substance problem; for an obvious first step in this direction is taken when the relationship between I and is investigated; and the central issue concerning many of the theorists in the indexicals field can be put as follows: [A sentence involving I] doesn't identify a proposition. For this sentence is not true or false absolutely, but only as said by one person or another... There is a missing conceptual ingredient: a sense for which am the reference, or a complex of properties alone have, or a singular term that refers to no one but me. (Perry 1979, 6-7) Many researchers are struck by the logical difficulties involving statements that contain I as compared with statements apparently relating the same facts or state of affairs but in the third person. Of course, any kind of bifurcation between statements involving I and statements in the third person cannot help but make one wonder whether consideration of some kind of dualist approach may be appropriate for dealing with such statements. hasten to add that Perry does not ultimately come down in favor of any kind of Cartesian dualism - his final formulation, indeed, is of behaviorist belief states, which cause people merely to act as though they have (private) beliefs-but on the other hand do find significance in his following admission: a theory of propositions of limited accessibility seems acceptable, even attractive, to some philosophers. Its acceptability or attractiveness will depend on other parts of one's metaphysics; if one finds plausible reasons elsewhere for believing in a universe that has, in addition to our common world, myriads of private perspectives, the idea of propositions of limited accessibility will fit right in. (Perry 1979, 16) Castaneda, too, seems to allude to issues involving dualism.2 In Omniscience and Indexical Reference, he says, for example: one can, of course, raise the problem of other minds. If there is a sense of 'know' in which one cannot know facts of the form 'X, different from me, knows that _', then there is a sense in which one cannot know another person's oratio recta indexical statements, whether they are about himself or not, and whether they are about physical or psychological matters. (Castaneda 1967a, 209) The effect of all this is to direct attention firmly towards the distinction (real, or only apparent) between public and private knowledge, that is, the distinction between that knowledge which is available to others and that which appears to be available only to the I (below shall call this distinction that between third-person knowledge and first-person knowledge). Of course, this is an epistemological distinction; but in my opinion it is not unreasonable to expect that looking at the problem from the point of view of epistemology will also shed at least a little light on the ontology of the I-others (and, by extension, the mental substance/physical substance) problem. …
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