It is a philosophical approach which guides scientific investigation. The thought comes before the investigation, and it is also an attempt to include an idea of God, which I assumed was a priority of yours. So, yes, it is not demonstrable, but it shows the direction in which his investigation led him.
Which is exactly what I and others are saying, but we are saying it inclusively, not excluding other ideas, traditions, experiences, and philosophies. Science cannot explain everything and should not dictate our philosophical debate, which is necessary for the discovery of areas of investigation.
Your use of the terminology “God of the Gaps” is so foreign to what we are saying as to be deceptive. This has been an ongoing experience with conservative Christians whose use of strawman arguments derails any real investigation. Just as the scientist who rules out theism is not scientific because he is barring any evidence that may come, theists who rule out interpretations of millennia-old scriptures that do not suit them are also not scientific.
But this is wrong. You may assume this. Some scientists have even assumed this. But it demonstrates no such thing. It is also quite possible that we cannot detect them because they don’t exist. They were imagined/invented to rescue theories which were not agreeing with observation. But it is also quite possible that the theories are wrong in some small part and it is this which produces these discrepancies. By claiming it points to things which cannot be measured is a “God of the Gaps” type argument. Don’t get me wrong. I believe in things which cannot be measured. I simply don’t claim that some unsolved problem in science demonstrates that these things exist. They do not.
This strikes me as somewhat like my current view which is that what we call consciousness is a process where two ‘realms’ interface and is thus a cooperative effort between the physical/material and the spiritual – which is what I would expect from applying the description of Adam becoming a “living soul”, a thing of spirit and physical body at the same time.
I vaguely recall a sci-fi story where minds were being viewed from two realms (which roughly correspond to “material” and “spiritual”); mind couldn’t be fully explained from either view though both could come close. So I expect that there will never be a fully ‘material’ explanation for consciousness.
Dark matter and dark energy were indeed “invented” or, better, hypothesised, to reconcile theory with observation, but this is a standard, evidence-driven process in science, not merely an ad hoc rescue of failing theories, but a method to guide further investigation and refinement of our understanding of the universe. You make it sound “off the cuff”!
The basic fact is there was no actual evidence such things existed and there remains no evidence they exist. It is why they are called “dark.” The are basically fudge factors, and some physicists come up with theories for eliminating any need for them.