That is, they think all of their decisions were preordained, and then use this to claim that they can’t be held responsible for anything they do.
I’m a fairly hardcore/radical determinist, and tend to agree that individuals shouldn’t be held morally responsible for actions, any more than a hammer is morally responsible for driving a nail. However, that does not mean people should be free from consequence. There are plenty of reasons - even as a hardcore determinist - to hold people to account for their actions, either as a social corrective mechanism, public safety, deterrent, or personal sanity.
As for getting their actions to align with your morals, that’s a more complicated question that depends on the type of person they are.
Any claim that is asserted without evidence can be dismissed without evidence.
Any claim can be inverted, so lacking evidence in either direction, this applies to the inverse as well.
I personally prefer more psychologically rooted arguments that lean towards at least compatibilism. If a belief in free will, regardless of the actual fact, is sufficient to affect one’s actions, is that not evidence against hard determinism?
Nah. It just extends down. Your belief, and any changes over time, are also predetermined as some sum of your inputs.
Sure, but the compatibilist view is, in my understanding, that determinism is true, but we still have free will. The mind is so complex its deterministic function can’t be fully predicted, so the outcome of particular inputs over any meaningful duration cannot be computed. Thus actual free will and the illusion of free are essentially functionally identical.
This is all just pointless speculation.
Dismissing a claim is not equivalent to asserting the negated claim.
Right, but lacking any physical evidence in either direction, is it not reasonable to then turn to purely rational explanations if we want to arrive at some sort of belief?
Why would we want to do that? Why believe things for which there is no rational basis?