Well pre-Enlightenment, science was called "natural philosophy." The word "science" never surfaced until the 18th century.
Both science and philosophy are basically analytical processes, "extracting meaning from what we see, and projecting meaning out beyond what we can see."
Still to the extent that science depends on observables, it cannot account all by itself for everything that is, which realistically includes "non-observables" such as logic and physical laws. In short, it relies for the prosecution of its own business on entities that its own method cannot explain or account for.
Then there is the small matter of whether reality reduces to the observable. Human beings are strongly visually-oriented. Which I gather is why such a premium is placed on "observability." But this is not the same thing as saying that all of reality reduces to the observable; merely that human beings will tend to focus on it, to the exclusion of anything else that might exist, though not in a physically observable state.
Then there is that saying, "in the mind's eye." The human mind can "see" non-observables. Which tells us that reality does not finally reduce to what the physical eye can tell us.
Thanks so much for your excellent post, marron!
The word seems to have entered into English between 1300 and 1350.
Thank you for your excellent posts! Truly we need to explore the observer problem in the broad context. It's not just in quantum mechanics, it's in relativity, philosophy and theology.