In the Liar's Paradox the 'paradox' is that we cannot know if that particular statement is valid. As I see it, the resolution of the Liar's Paradox is that the logic related to contradictions is contained in that statement: the statement contains the proposition that self-contradiction of itself negates validity. For a paradox to exist in that statement — for us to be unable to know whether that particular statement is valid — the originator of that statement therefore has made at least one statement that is not a lie, or at a minimum could have made a statement that wasn’t a lie.

The statement is telling us that we cannot learn which statement(s) the originator of that statement might have made that is(are) not a lie by interrogating its originator. That does suggest, however, that the source of knowledge is critical to establishing the possibility of its validity: if the source is incapable of lying, interrogating it (as science 'interrogates' physical existence) can definitely yield valid knowledge related to what is being interrogated — though in the case of science the contingency of that knowledge, due our infinite ignorance, must be recognized. That is a recognition of incompleteness, but incompleteness does not negate the validity of knowledge based on information gleaned to this point — though it is always provisional.