Taking the case of Schrodinger's cat, if the measurement of the cat is not yet done, then I don't know whether the cat is dead or alive. Epistemologically speaking, since I don't know about the condition of the cat, it is in a superposition state of both dead and alive. But if my friend opens the box and measures it without my knowledge, then for me the cat is still in a superposition state. If QM is epistemological in its complete sense then the collapse of the wave-function is relative. For him, the cat could be dead and for me, it could have a finite probability of being alive. If my knowledge was the only factor that determines whether the state is in superposition or not (epistemology), then there would be a finite probability that I opened the box and found the cat alive and removed it from the box and go and meet him!. Einstein too said (in the context of relativity) that reality is relative but here(QM) it takes an entirely new meaning.
And what if I forgot that I have measured? There would be a finite probability that I measured it to be dead and then forgot and then again measured it only to find that it was alive!
Is QM completely epistemological? If yes then is the forgetting argument valid?
Both of them make no sense to me, but reality need not make sense to me.