Is the statement "Claims demand evidence" always true?

[Mudhammam]

This is an assumption that doesn't bear up to scrutiny. The fact is that you and I can both examine an object and come to agreement about its properties based on our perceptions and where those perceptions overlap. We can thereby ascertain that the object is material and not an abstraction. Simply because the event of perceiving happens in the mind doesn't mean that what is perceived is an abstraction. You're equivocating "abstraction" and "mental event".

I have to disagree with your framing here, though you're right that we can come to an agreement about the nature of physical objects using our perceptive faculties as interaction with external phenomena occurs in what you call a "mental event." But this is different from the faculties themselves, which involve abstractions, or definitions 2 and 3a in the M-W Dictionary. It is the mental event that translates objective existence into subjective experience, but without a process of abstraction (specifically, rationality) the content would possess no discernible meaning. One of the major problems since Plato is making headway on the following question: In what manner do the categories by which "mental events" organize themselves into a coherent or rational framework exist? Are these categories, which are abstractly related, "out there" in the world? or do they come from within ourselves? Must it be one or the other? When one makes a claim about the justification of belief, are they not stating a fact about such abstract relations, namely, the relation of truth to the individual and to the world? Does not "truth" exist in the purest sense of "being," and isn't this an abstraction and not only a mental event (as you delineated it)?