The Nachlass of A.N. Prior
a joint project between
Department of Information Studies - University of Copenhagen
and
Department of Communication and Psychology - Aalborg University

It's true but I don't believe it

By Arthur N. Prior on NA/NA/NA

This text has been transcribed by Sara L

Download the PDF of this item
Please note that this text is extracted from the PDF, and is as such most likely not styled properly.
'It's True but I don't Believe it'by A.N.Prior. [Suppose a person says 'I think it's raining though of course it isn't really'; or 'It really is raining; though of course I don't]Suppose a person says 'I think it’s raining --- though of course it isn't really'; or 'It really is raining, though of course I don't think so' (or 'though of course I think it isn't). It would be generally agreed that these are odd pairs of statements for anyone to make; but philosophers have been strangely hard put to it to say just what is wrong with them. They are not, it is clear, simply self-contradictory; in fact, both members of any of these pairs might be true. For example, I might sincerely & truly say that I think that it is raining, & insincerely that it really isn't; & it might nevertheless be really not raining, so that my second statement also would be true, though
unintentionally. [So it is not the laws of ordi] Hence, it would seem, it is not by the laws of
ordinary logic that such conjunctions as these are to be condemned; what they contravene must be some special 'logic of belief'.[Prior’s note: Bottom left margin contains a list “10.36 10.53 for Square 11.13 for Paper.”] {1}[There is]Suppose a person says 'I think it's raining - though of course it isn’t really’; or 'It really is raining; though of course I don't believe it is’; or 'Though I believe it isn't raining, it really is.' It would be generally agreed that these are odd statements for anyone to make; but philosophers have been strangely hard put to it to say just what is wrong with them. They are not, it is clear, simply self-contradictory; in fact, any one of them might actually be true. For I might, e.g., say 
This text has been edited by Fabio Corpina, Adriane Rini and Peter Øhrstrøm. It has been written on papers from University of Canterbury, Christchurch, New Zealand. This has been crossed out in the original MS. This has been crossed out in the original MS. [Prior’s note:] Bottom left margin contains a list “10.36 10.53 for Square 11.13 for Depart.” [Transcribers’ note:] The next page appears to be an earlier draft of above. This has been crossed out in the original MS.
sincerely that I think it is raining, & insincerely that it really isn't, & it might nevertheless be
really not raining, so that in saying that it isn't I would have inadvertently told the truth. {2} So it
is not the laws of ordinary logic - say, of the 1s propositional calculus - that statements of this
sort violate, & it might well be thought, & has been sometimes thought, that what they
contravene is some special logic {3} T(f)xp = KTxpNp D(f)xp = KTxNpp Fx = pAT(f)xpD(f)xp. T(i)xp = ^KTxp[N]BxNPxTxpNBxp. D(i)xp = ^KTxNp[N]Bx[N]p. [KTxNpNBxNp.] Ix = p AT(i)xpD(i)xp.
(1) CKTxpTxBxNp - AKTxpBxNp --- T(i)xp - KTxBxNpNBxNp. --- T(f)xBxNp.
(2) CKTxNpTxBxp
- AKTxNpBxp --- D (i) xp.
- KTxBxpNBxp
T(f)xp.
(3) CKTxpTxNBxp
AKTxp[BxNp]10NBxp. --- T(i)xp
- KTxNBxpBxp --- D(f)xp.
[CKTxNpTxNBx]11
This word is unclear. This word is unclear. The text in [] has been crossed out in the original. 10 The text in [] has been crossed out in the original.

[ CKNpAKNpKNpNNp
CKNppAKNppKpNp]12
CKpqAKprKqNr
CKpqAKprKqNr
CKpqAKpNrKqr 
11 The formula in [] has been crossed out in the original. 12 The formulae in [] has been crossed out in the original.
  www.priorstudies.org •  University of Copenhagen •  Aalborg University •