Proof Mind is Fundamental and Matter Doesn't Exist

[Angrboda]

Step 2 is a fallacy, the same that is used by God/Ghost/Bigfoot/UFO believers all the time. Saying something cannot be shown to be imposible doesn't demonstrate that it is possible.

E.g. I claim that inside a box that you cannot examine lives a leprechaun.

You not being able to prove it doesn't exist does not constitute evidence that it could exist.

i'm not saying it 'can't be shown' to be impossible. i'm saying it is epistemically impossible to to disprove solipsism. that means, for all we know and all we could know solipsism is possible or could be true. and given that is the case, I think it is reasonable to conclude it is actually possible since the only alternative is nihilism which is self defeating. the substantiation of premise 2 is that the prospect of solipsism being possible is the only reasonable conclusion given our epistemic knowledge; which is that for all we know and could know solipsism could be true. I think the wording of the premise made it clear it's not reasonable to conclude solipsism is impossible and you can't reasonably be agnostic on this issue because that would mean you don't think the only current and possible knowledge we have is sufficient to establish what's true of reality which is nihilism.

This is an appeal to consequences. It is impossible to prove idealism false. It's also impossible to prove idealism is true. The evidence for and against is equal. Agnosticism is the currently reasonable view.