FOM: indubitability (or "certainty")

[Neil Tennant]

*Kripke's Wittgenstein* doesn't always use unsurveyable proofs as an example.
There is nothing unsurveyable about the problem "57+68=?" in the thought
experiment that Kripke conducts on the thought-experimental assumption that
the subject has never before had to add together any two numbers either of
which exceeds 57. 
Of course, one could generate a great variety of similarly surveyable problems
(and indeed, ones whose solutions can be proved to be correct by means of
surveyable proofs) that would serve the same thought-experimental role that
Kripke intended. That role, to repeat, was to underscore the possibility that,
despite a subject's having "passed our tests" of linguistic competence on
(necessarily only finitely many) examples in the past, he/she might not have
cottoned onto the rule that the community takes to be associated with the
sign in question (here, "+").  Thus, in Kripke's example, we are unable to
rule out the possibility that the subject will have *added* the numbers
whenever they are both less than 57; but that, when given the problem 
"57+68=??", he/she will *quad* them, giving the answer "5" instead of "125".

Neil Tennant