Full Idea
An essential feature of the liar paradox is the application of the truth predicate to a sentence with a negated occurrence of the truth predicate, though the negation can be avoided by using the conditional.
Gist of Idea
The liar paradox applies truth to a negated truth (but the conditional will serve equally)
Source
Volker Halbach (Axiomatic Theories of Truth [2011], 19.3)
Book Reference
Halbach,Volker: 'Axiomatic Theories of Truth' [CUP 2011], p.275