Full Idea
Either J and the judgment 'I say that J is true' are the same for all judgments or for none. But if identical, their denials are identical. These are 'J is not true' and 'I do not say that J is true', which are different. No judgment judges itself true.
Gist of Idea
That a judgement is true and that we judge it true are quite different things
Source
Charles Sanders Peirce (Criterion of Validity in Reasoning [1903], I)
Book Reference
Peirce,Charles Sanders: 'Philosophical Writings of Peirce', ed/tr. Buchler,Justus [Dover 1940], p.121
A Reaction
If you are going to espouse the Ramseyan redundancy view of truth, you had better make sure you are not guilty of the error which Peirce identifies here.