Truth is not absolute.


 * Uncertainty or non-absoluteness of truth value always involves some kind of confusion or ambiguity regarding the distinction between the sentential predicates true and false. Where these predicates are applied to a more specific predicate and its negation - e.g., "it is true that the earth is round and false that the earth is not-round" - the confusion devolves to the contextual distinction between these lesser predicates, in this case round and not-round within the context of the earth.  Because all of the ambiguity can be localized to a specific distinction in a particular context, it presents no general problem for reality at large; we can be uncertain about whether or not the earth is round without disrupting the logic of reality in general.  However, where a statement is directly about reality in general, any disruption of or ambiguity regarding the T/F distinction disrupts the distinction between reality and not-reality. Were such a disruption to occur at the level of basic cognition or perception, reality would become impossible to perceive, recognize, or acknowledge as something that "exists".
 * Since a tautology is a necessary and universal element of this syntax, tautologies can under no circumstances be violated within reality. Thus, they are "absolute knowledge".  We may not be able to specify every element of absolute knowledge, but we can be sure of two things about it: that it exists in reality to the full extent necessary to guarantee its non-violation, and that no part of it yet to be determined can violate absolute knowledge already in hand.  Whether or not we can write up an exhaustive itemized list of absolute truths, we can be sure that such a list exists, and that its contents are sufficiently "recognizable" by reality at large to ensure their functionality.  Absolute truth, being essential to the integrity of reality, must exist on the level of reference associated with the preservation of global consistency, and may thus be duly incorporated in a theory of reality.
 * On the other hand, the fact that any reasonable definition of "absolute truth" amounts to tautology can be shown by reversing this reasoning.  Since absolute truth must be universal, it is always true regardless of the truth values of its variables (where the variables actually represent objects and systems for which specific state-descriptions vary in space and time with respect to truth value).  Moreover, it falls within its own scope and is thus self-referential.  By virtue of its universality and self-reference, it is a universal element of reality syntax, the set of structural and functional rules governing the spatial structure and temporal evolution of reality. As such, it must be unfalsifiable, any supposition of its falsehood leading directly to a reductio ad absurdum.  And to ice the cake, it is unavoidably implicated in its own justification; were it ever to be violated, the T/F boundary would be disrupted, and this would prevent it (or anything else) from being proven.  Therefore, it is an active constraint in its own proof, and thus possesses all the characteristics of a tautology.
 * To perceive one and the same reality, human beings need a kind of "absolute knowledge" wired into their minds and nervous systems.  The structure and physiology of their brains, nerves and sense organs provide them, at least in part, with elementary cognitive and perceptual categories and relationships in terms of which to apprehend the world.  This "absolute" kind of knowledge is what compels the perceptions and logical inferences of any number of percipients to be mutually consistent, and to remain consistent over time and space.  Without the absoluteness of such knowledge - without its universality and invariance - we could not share a common reality; our minds and senses would lie and bicker without respite, precipitating us into mental and sensory chaos.  Time and space, mind and matter, would melt back into the haze of undifferentiated potential from which the universe is born.
 * Because the truth-Truth distinction is just one of certainty, i.e. probability, everybody who claims "truth" (t) implicitly claims some measure of "Truth" (T), or the attribute denoting inclusion in a formal system or recognizable class of facts or perceptions mutually related by an inferential schema or "scientific theory" (which is required to exhibit logical consistency and thus to tacitly incorporate the formal system of logic). That is, scientific truth t is just the assignment of a subunary, usually subjective probability to logical truth T; if t does not come down to a probabilistic stab at T and thus devolve to generative logical inference, then it is meaningless.