All science is materialistic

[polymath257]

Which, again, is to my point. The label (material, physical, etc) is irrelevant. What is important is whether the ideas are testable via observation.

You're pounding on open doors.  Non-material explanations are not testable.  Of the 20 million or so scientific papers published in the last century, cite a single one that addresses "non-material" forces.

The point is that there is nothing inherently non-scientific about a hypothesis that ghosts exist and they are not made out of atoms. That this hypothesis has actually been tested and shown to be wrong is another aspect.

There is nothing inherent in the scientific method that restricts its analysis to 'material' things. if anything, the concept of 'material' ultimately becomes *defined* as that which can be tested. But the more fundamental concept is that of testability, not of materialism.