Hardly a scientific question, eh? Certainly you agree that in the realm of science the assumption of naturalism has been very fruitful? It seems to me that supernaturalism will have to establish a similar track record to displace it.
Example (pertaining to this discussion):
If everything was created by nature without Intelligent Design If man was created by nature and acts only through nature Nothing man creates has Intelligent Design because it is natural.
If man does have Intelligence and it was given to him by nature nature must have Intelligence built into it Since nature created everything What is nature?