Then here we go.
You are caused by something else independent of your mind. But we know, that 1st person experiences are sometimes hallucination.
In effect objective reality can cause unreal experiences. So how do you know, that this is not the case now?
There are many versions of that in practice, but here it is general.
Real objective universe -> you experience you as real.
Not real objective universe -> you experience you as real.
That is the problem. I can't prove even with evidence that I live in a real objective universe. But that is not unique to me, hence this:
"
Naturalism's axiomatic assumptions[edit]
All scientific study inescapably builds on at least some essential assumptions that are untested by scientific processes.
[43][44] Kuhn concurs that all science is based on an approved agenda of unprovable assumptions about the character of the universe, rather than merely on empirical facts. These assumptions—a paradigm—comprise a collection of beliefs, values and techniques that are held by a given scientific community, which legitimize their systems and set the limitations to their investigation.
[45] For naturalists, nature is the only reality, the only paradigm. There is no such thing as 'supernatural'. The scientific method is to be used to investigate all reality,
[46] and
Naturalism is the implicit philosophy of working scientists.
[47] ..."
Philosophy of science - Wikipedia