Existential Logic and Not Knowing
Logic is not limited to its expression in the scientific method and in the formal presentation of proof in argument, as in a court. Logic has many applications outside these narrow boundaries, as becomes obvious as soon as we consider the existential context.
Imagine the case in which A is true, and an individual X knows that A is true, but has not the means of proving the truth to the satisfaction of Y. The inability to "prove" the fact does not alter the essential story, namely, that X knows the truth; Y does not.
Imagine that a crime has been committed, and there is insufficient evidence to permit either a universal knowledge of the facts or a proper social response. There may be plenty of "proof" in the existential sense, for individuals in contact with the immediate situation, but none at all for the wider world peacefully sleeping and awaiting the news reports.
Through poor education, the scientific method becomes for many a tool for the affirmation of ignorance, rather than a tool for attainment of knowledge.
The words, "There is no evidence," are primarily a shout that one does not see or know. It is an excellent thing to know that one does not know, but it is only the barest subjective affirmation, not to be confused with the positive knowledge that A is not true, simply because Y has no convincing evidence of the fact. Also, what convinces one may not convince another.
The constitutional bias of the western courts favors the accused. Similarly, the scientific method favors the discovery of those facts that arise out of the contemporary social and organizational context. Existential truth becomes "testimony," which is considered only a weak from of evidence.
This built-in tilting of the scales is an artificial arrangement based on a deliberate cognitive bias, one favoring what we mistakenly call the "objective" world, as distinct from the "subjective" world experienced by each individual.