Full Idea
The redundancy theory is unable to account for the inference from "Oscar's claim is true" and "Oscar's claim is that snow is white" to "the proposition 'that snow is white' is true", and hence to "snow is white".
Gist of Idea
The redundancy theory cannot explain inferences from 'what x said is true' and 'x said p', to p
Source
Paul Horwich (Truth (2nd edn) [1990], Ch.2.9)
Book Reference
Horwich,Paul: 'Truth (2nd edn)' [OUP 1998], p.39
A Reaction
Earlier objections appealed to the fact that the word 'true' seemed to have a use in ordinary speech, but this seems a much stronger one. In general, showing the role of a term in making inferences pins it down better than ordinary speech does.