I dont have all the modern philosophical terms down, but I cannot see how materialists/physicalists can make any claims. If there is nothing but physical universe, then there is no “truth”. Actually claims dont even exist. It takes an agent or a mind, and there is no real agent nor mind. The correspondence theory of truth doesnt work in a monist physical universe. The “cash value” idea also doesnt work. Where can I read about someone trying to answer my issue with materialism? Im not sure I even know the terms well enough to search, and have tried a bit. And/or what is your attempt to address them?
Modern physicalists generally do not argue any more that physicalism is actually monisitc. Here are three references published in the last two decades, that all agree that there are non-physical things in our universe:
https://www.amazon.com/Physicalism-Problems-Philosophy-Daniel-Stoljar/dp/0415452627/ref=sr_1_1?crid=32B84H7IR1HAM&keywords=physicalism+stoljar&qid=1641511847&sprefix=physicalism+stoljar%2Caps%2C153&sr=8-1 https://www.amazon.com/Physicalist-Manifesto-Thoroughly-Materialism-Philosophy/dp/0521827116/ref=sr_1_1?keywords=melnyk+physicalist&qid=1636559493&s=books&sr=1-1 https://www.physicalism.com/Rise-Physicalism.pdf
They do not even claim that non-physical things cannot be causal. Instead, they claim that non-physical things are somehow causally dependent on the physical -- hence all causation that affects the physical is traceable back to some physical earlier cause.
A proof of the dependence of math, morality, consciousness, or information on the physical has generally not been successfully achieved, therefore the secondary nature of these other non-physical things in a physicalist ontology is basically asserted as dogma, rather than being a supported position. But within that dogma, claims, agents, correspondence, truth, ideas, etc are accepted, and treated as non-physical but dependent. Physicalism today is sort of an monism and two halfs ontology, rather than a pure monsitic ontology, and claims use the extra halfs of the non-physical.
For a more complete discussion of this problem, see this question and answers: Name for a form of naturalism that allows for abstract objects