Under this heading are found two manuscripts, 11a and 11b. The first, entitled “The Paradox of the Liar”, is a long, rambling set of working notes on the foundations of logic, in the spirit of the earlier Paper 5a. The second, entitled “P.L. p. 89”, is much shorter and was intended to continue the discussion of folio 89 of 11a; the present title of 11b is editorially supplied.