Quasi-indexicals and knowledge reports (Q2754609)

In this article the authors present a computational analysis of de se, de re and de dicto belief and knowledge reports. The main aim of the paper is to solve a problem first observed by Castañeda. The principle of veridicality for knowledge reports `(\(A\) knows that \(P\)) implies \(P\)', which states that knowledge is true, fails to hold if \(P\) contains a `quasi-indexical'. Quasi-indexicals are expressions in intentional contexts that represent a use of an indexical by another person. E.g., in `John wrote himself a letter', `himself' is a pure-indexical, whereas in `John believes that he (i.e. he himself) is rich' `he' (or `he himself') is a quasi-indexical. The problem that de se knowledge reports with quasi-indexicals pose is that the quasi-indexical in the consequent is not in the scope of an intentional verb. Hence, it does not have an antecedent (* a quasi-indexical). NEWLINE\[NEWLINE(A \text{ knows that * is \(F)\rightarrow\) (* is }F)NEWLINE\]NEWLINE As a result, it is not possible to detach the consequent because it cannot stand by itself. The solution offered by the authors is based on the thesis that knowledge is true belief. De re knowledge reports of the form (\(A\) knows of \(N\) that \(F)\rightarrow (N\) is \(F)\) are then analyzed as follows: NEWLINE\[NEWLINE\begin{multlined} (X \text{ believes \(A\) knows of \(N\) that }F)\\ (X \text{ believes that \(A\) believes of \(N\) that }F) \wedge (X \text{believes that \(N\) is }F).\end{multlined}NEWLINE\]NEWLINE Next, de dicto knowledge reports are shown to be reducible to de re knowledge reports. De se knowledge reports are then analyzed as a species of de dicto knowledge reports. The agent \((A)\) is represented in the belief system of the believer \((X)\) in a way that is neutral with respect to any properties (including his/her name) ascribed to it by the believer. The authors therefore present a theory of how self-concepts can be represented in knowledge systems that is similar to the way of how temporal indexicals like `now' are represented.NEWLINENEWLINEFor the entire collection see [Zbl 0957.00013].