(September 19, 2016 at 2:02 pm)Alex K Wrote: If it did, Ghosts would simply become part of an extended version of physics, the same way radio waves were incorporated into our understanding in 1886 or so. I don't understand where "immaterial" would come into play.
The concept of immateriality actually traces back to the problem of universals, realism versus nominalism, and the ontological status of things like essences, numbers, categories, and ideas. In my experience, people who call themselves "materialists" are at root nominalists.