Résumé
In relation to Frege’s claim that one can express the same thought today by means of ‘yesterday’ that one expressed yesterday by means of ‘today’, Perry remarks:
But should the Thought be the same? The belief expressed by "The midterm elections be today" on Tuesday motivates responsible citizens to go to the polls. The belief expressed by "The midterm elections be yesterday" on Wednesday will not motivate responsible voters to go to the polls. It seems the cognitive significance of the beliefs are different (Perry, J., Revisiting the Essential Indexical, 2020, 51-52).
In contrast with this, Kaplan, who once held a similar view claims:
I may be tracking the passing days very carefully. I became acquainted with the day yesterday and expressed that way of being acquainted in my use of ‘today’. Assuming no recognition or tracking failures and no memory failures, I should be able to continue to have the day in mind in the same way today, though of course I will refer to it as ‘yesterday’. Here we see, …, that the cognitive significance of an utterance should not be identified with linguistic meaning… We need to leave linguistic meaning and turn to industrial-strength ways of having in mind to give a proper analysis of the notions in this area. (Kaplan, ‘An idea of Donnellan’, 2012, 138).
In following Kaplan in that we need to turn to industrial-strength ways of having in mind since, inter alia, it is not obvious what relation between the utterances of ‘today’ and ‘yesterday’ must obtain in order to ensure the internal continuity that constitutes retaining the original belief (Kaplan, Demonstratives 1989, 537, n. 64), I argue that ways of having in mind are best spelt out in terms of (neo-)Fregean persisting modes of presentation. True, this makes them short of being explanatory of the subject’s behaviour as something they are supposed to do. But, neither are, or so I shall argue, the linguistic meanings of ‘today’ as ‘yesterday’ – as alternative contenders for being the bearers of cognitive significance – fit for this role, so much emphasized by Perry. As a result, the thought that is expressed stays the same through the change of context, "despite lower-level differences" (Evans, G., The Varieties of Reference, 196).
