10.11575/PRISM/16285
Kang, Osbert Jian
Frederic Fitch and epistemic blindspotting
University of Calgary
1990
B 820.3 K36 1990
Epistemics
Fitch, Frederic Brenton
University of Calgary
University of Calgary
Kazmi, Ali Akhtar
2005-07-21
2005-07-21
1990
doctoral thesis
Kang, O. J. (1990). Frederic Fitch and epistemic blindspotting (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/16285
0315669462
http://hdl.handle.net/1880/18017
B 820.3 K36 1990
vii, 173 leaves : 30 cm.
University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
Bibliography: p. 162-173.
This thesis investigates the problem of epistemic blindspotting initiated by Frederic Fitch's Theorem 5 (FT5) which says: if there is some true proposition which nobody knows (or has known or will know) to be true, then there is a true proposition which nobody can know to be true. An epistemic blindspot is defined as a proposition which, though true, cannot be known (to be true). Fitch did not consider the factors of time and agency in his proof, and he indicated that a more detailed treatment should take those factors seriously. This thesis first supplies that more detailed treatment by giving a complete version of the formal proof of FT5 with quantifiers over agents, time and eternal sentences. The thesis further strengthens Fitch's result by refuting the attempts of Schlesinger and Edgington to dissolve Fitch's result, and by showing that FT5 holds with the modal expression 'can' interpreted either as logical possibility or as ability. It shows that even the weakest classical modal system yields Fitch's result. It also proves a theorem which indicates that even some doxastic concepts generate potential epistemic blindspots. With respect to the philosophical implications of Fitch's result, the thesis shows that for any true proposition, we cannot identify it as being an epistemic blindspot. This position was supported by proving the following two conclusions. First, for any true proposition, nobody is able to know that it is a true proposition which nobody is able to know to be true. Secondly, for any true proposition, it is logically impossible to know that it is a true proposition which it is logically impossible to know to be true. So even if there are epistemic blindspots we cannot locate them. It is made clear that while FT5, together with the plausible assumption that there are unknown true propositions, establishes that it is possible that there are epistemic blindspots, it is also possible that there are no epistemic blindspots. This conclusion is based on the facts that FT5 does not prevent us from knowing true atomic propositions, and that FT5 does not prevent us from knowing a proposition of the form 'Kp', where 'p' is an atomic proposition. For all that FT5 shows, perhaps .every true proposition may be known at some time or other. Nevertheless, FT5 establishes a formal limit to human knowledge and helps us to understand some of our epistemic concepts.