Spirit releasement

Why is science any more needed when everything is known already?
I'm sorry if this statement was intended as satire, but if not, isn't this an inversion of the classic materialist argument?
That sentence was partly satire, but I was also sincere because I really wonder how some people can be so certain about already knowing it. I hoped that somebody more knowledgeable here would have given more stuff and good points.

I think empiricism and scientific rigor are absolutely needed in evaluating the afterlife. Such phenomena as for example multiple personality and sleep paralysis must be known before one can say there were spirits in action. Even although these two phenomena certainly are not completely explained.

I have seen enough to be sure that many psi-phenomena are real.