"I hope you don't mind if a non-scientific observer on the list interjects himself into the discussion."
Not at all; the more the merrier.
"Since the mechanism here isn't know what is the scientific basis for choosing 'unknown natural mechanism' over 'no known natural mechanism'? Given the absence of any knowledge about the actual process involved wouldn't this just be a guess and not a scientific conclusion?"
Just to clarify things so that we are on the same wavelength, there are two mechanisms involved here. One is the mechanism(s) that account for events during the Planck Era; the other is the mechanism(s) that account for events after the Planck Era. We know almost nothing about the former, though that may change if we are ever able to combine general relativity and quantum mechanics into a Theory of Everything (ToE). As such, there is no scientific basis for choosing "unknown natural mechanism" over "no known natural mechanism". I wouldn't call it a guess, however, because at the very least historical precedence tells us that there are likely to be no natural phenomena that cannot be explained by natural mechanisms.
For the latter mechanism(s), however, this is not the case. We have a much better idea of what happened after the Planck Era, both because of mathematical models (the grand unified theory, the electroweak theory, the inflationary theory, etc.) and because we can to a certain extent recreate some of the conditions that existed after the Planck Era so that we can test the models. Here there is a strong basis for choosing "unknown natural mechanism" over "no known natural mechanism". And this would be counted as an actual scientific conclusion.
"I hope I don't look to foolish asking this question but is this situation a parallel to archeological research?"
No question is foolish, especially such simple questions as this. Sometimes the simplest questions can have the most profound answers. However, the analogy between archaeology and cosmology is not good for one main reason. When an archaeologist finds a pottery shard he can immediately recognize it as an artifact because he knows (often from personal experience) that pottery is a set of artificial objects created by artificial means. If necessary he can compare his shard with pottery being made today to confirm what it is. A cosmologist on the other hand has no prior experience (personal or otherwise) to fall back on, nor any other similar or identical artifact to compare the universe with. As such, the "fact" that the universe was created by an intelligent being is far from obvious. He would need other kinds of evidence, and not negative evidence. He cannot make a case for the universe being an artifact based simply on his lack of imagination or luck or ability to find a natur
al explanation. He would need to find actual positive evidence that shows that the universe is an artifact to be able to make such a conclusion. So far, no such positive evidence has been found.
Kevin L. O'Brien