***You [Duane] said that I assume that: "1. There is nothing more to humans then the physical properties we know about." [sic] If I am assuming anything, ie. if I am taking something as a foundational postulate, then it is that we should not consider anything other than what we learn via empirical observation, experimentation and the methodical testing of hypotheses. Therefore I reject the supernatural, not because I assume it is non-existent a priori, but rather because I have no evidence of it. If I can obtain a scientifically satisfying, consistent theory of consciousness without invoking supernatural causation, then I can avoid the massive rearrangement of my entire scientific ontology that acceptance of the supernatural would entail. (see Occam's Razor)***
Ockham was a theist. Does that make a difference?
Seriously, though, the problem with your view is that Occam's razor is not an adequate tool to justify scientific belief. It works in conjuction with other facets of good science, but by itself it is not acceptable.
In terms of 'consciousness' it is neither valid or invalid to assume anything. The key is what method will progress likely result? Will progress likely result from spiritualism, or mind reading, etc, to understand what consciousness is, or will progress be more successful by applying scientific methods? If applying scientific methods is it better to assume a reductionist naturalistic explanation or a non-reductionist supernatural explanation?
This, in my view, is how science should proceed. The blatant response that science rejects supernaturalism because it is contrary to Occam's razor is misleading and open to a whole slew of philosophical difficulties that anti-realists have had a field day making known.