We discuss misinformation about “the liar antinomy” with special reference to Tarski’s 1933 truth-definition paper .
Lies are speech-acts, not merely sentences or propositions. Roughly, lies are statements of propositions not believed by their speakers. Speakers who state their false beliefs are often not lying. And speakers who state true propositions that they don’t believe are often lying—regardless of whether the non-belief is disbelief. Persons who state propositions on which they have no opinion are lying as much as those who state propositions they believe to be false. Not all lies are statements of false propositions—some lies are true; some have no truth-value.
People who only occasionally lie are not liars: roughly, liars repeatedly and habitually lie.
Some half-truths are statements intended to mislead even though the speakers “interpret” the sentences used as expressing true propositions. Others are statements of propositions believed by the speakers to be questionable but without revealing their supposed problematic nature.
The two “formulations” of “the antinomy of the liar” in , pp.157–8 and 161–2, have nothing to do with lying or liars. The first focuses on an “expression” Tarski calls ‘c’, namely the following.
c is not a true sentence
The second focuses on another “expression”, also called ‘c’, namely the following.
for all p, if c is identical with the sentence ‘p’, then not p
Without argumentation or even discussion, Tarski implies that these strange “expressions” are English sentences.
 Alfred Tarski, The concept of truth in formalized languages, pp. 152–278, Logic, Semantics, Metamathematics, papers from 1923 to 1938, ed. John Corcoran, Hackett, Indianapolis 1983.