The point is that there is no such thing as an objective observer. The observer can never be sure that his observation corresponds to objective reality. It's a real philosophical problem that no one has been able to solve. Logical positivism was the latest attempt - it was thoroughly refuted and discredited.
If you have solved it, then please enlighten us all because all of the great thinkers in history have failed.
True. However, you are forgetting that science relies on more than just one observer making the observation. Statistically, the sum total of these observations will "flatten out" giving a result as close to objective as humans are likely to get.
The point is that there is no such thing as an objective observer. The observer can never be sure that his observation corresponds to objective reality. It's a real philosophical problem that no one has been able to solve. Logical positivism was the latest attempt - it was thoroughly refuted and discredited. If you have solved it, then please enlighten us all because all of the great thinkers in history have failed.
So it's b) "making excuses". That's what I figured.
Look, you can practice philosophical Onanism all day long about how we can "never be sure" that our observations or conclusions "correspond to objective reality" -- lord knows some philosophers spent a lifetime at such pointless navel-gazing. But so what? Yeah, we *might* be wrong. If you're going to agonize over that little doubt to the point where it paralyzes your mind, and makes you unable to draw conclusions from even the most careful examinations of the real world because you're wringing your hands over the obvious fact-of-life that you *could* be mistaken to some degree through "subjectivity" or other form of error, then you're even *more* wrong than if you had taken a stab at figuring things out, and you'll *stay* wrong.
You say, "It's a real philosophical problem that no one has been able to solve." Sure, there's no "solution" if you insist on achieving absolute certainty, total perfection, complete infalibility in your reasoning. That's impossible. So why waste your time trying it?
But people *have* solved this "real philosophical problem", by realizing that being so anal as to insist upon perfection, upon ironclad *proof* of correctness, is itself the actual problem. So chuck it. Instead, people realized that the *actual* goal was to achieve knowledge that, while not necessarily complete or perfect, was at least correct *enough* to work anyway. They found that there were methods which could be used to build and refine a body of knowledge which was reliable, usable, and effective. Even if it wasn't necessarily "the" truth, it was close enough to get the job done -- and could be further refined as necessary if parts of it were found to be defective in some way.
This realization first because widespread around 1650, and the people who began working out the methods which produced reliable knowledge were at first known as "natural philosophers", and later as "scientists". And their methods of deriving knowledge, testing it for reliability, weeding out subjective bias, and seeking out new directions in which to search became known as "the scientific method".
And it has worked fantastically well. It has produced more successful, useful knowledge about the Universe in a few hundred years than philosophy, religion, magical incantations, and all other attempted methods of controlling the Universe had managed to achieve in a hundred thousand years. It has enabled mankind to do things which not long ago were considered sheer fantasy, in the realm of pure magic: We can fly through the air, we can speak instantly to people on the other side of the planet. We can have discussions with people we've never met, in places we don't know (hi!). We can watch the Earth from the sky and watch hurricanes crawl across the oceans. We can peer inside the human body as it operates without cutting into it. We can walk on the Moon. We can store and replay sights and sounds for all time. We can control the lightning and make it do our bidding. We can cure diseases, mend limbs, restore sight, extend lifetimes. All this and much, much more that would have been pure sorcery, complete impossibilities, only a few lifetimes ago.
You say, "If you have solved [the 'problem' of being 'sure' that our knowledge 'corresponds to objective reality'], then please enlighten us all because all of the great thinkers in history have failed." No, they haven't failed at all. The "great thinkers in history" have developed science. And it has succeeded beyond any of their wildest dreams.
Can we "be sure", can we *prove* that the knowledge learned via science is perfectly in accord with "objective reality"? No, but then we've found that there's no need to. Science does not deal in "proofs". It doesn't need them. Only fools insist upon certainty, upon absolutes, for there are none to be found in this world -- not even in religion, because there are no guarantees that your chosen religion, or your chosen interpretation of your religion, is a right one, or a misguided mistake. The only "certainties" to be had, for those who can't live without a complete lack of doubt, are the false "certainties" of adopting a belief without "proof" and then just utterly refusing to entertain any notions that it could possibly be in error. We've all certainly seen our share of that kind of mindset in action.
But if it's *real* knowledge you want -- the kind that, if perhaps not 100% correct (and there'd be no way to be sure even if it was), is at least within close enough proximity to "the" truth to *work* as if it's "the real deal", then science is the way to acquire such knowledge. It's a collection of tried-and-true methods, and the resulting body of reliably-obtained knowledge, which have been tested, validated, checked, rechecked, and cross-checked against that *objective reality*, and uses the reality -- the real world -- as the final arbiter of which methods and which knowledge *fits* when measured against the yardstick of reality itself.
Atomic Theory may not be "objectively true" -- in reality matter may not "really" be made of atoms. But it *behaves* as if it is, and it responds to our manipulations as if it were, and that *itself* is real. It's real, useful, practical knowledge about reality.
Sure, that's not "proof" of "correspondence with objective reality", but it's a *damned* convincing demonstration of being "close enough" (and the size of "enough" can even be precisely quantified, like +/- 0.3%). This is the way of all science. It can't be "proven" once and for all, but it *works*, it *fits*. And that's actually more valuable than any "objectively true" knowledge if it happens to be useless.
You can handwave all day about "subjective error" if you want, but while it paralyzes you from drawing any conclusions about anything, I'll be drawing conclusions from the evidence and using them to achieve real-world results, and validating them by cross-checking with independently produced other results, and verifying by basing further predictions on the findings, then performing tests to ensure that those predictions match the results of the tests. After all that, *could* all the verifications and cross-checks "just happen" to come out the right way by accident or through coincidentally matching "subjective errors" at every step? Okay, it's *possible* -- but that would hardly be the smart way to bet, would it?
...and when those results match *other* results produced indpendently by other researchers, and fit like a jigsaw puzzle with *other* findings, in an entire internally-consistent body of knowledge with parts that fit and interwork smoothly like a Swiss watch, and... Well, you get the picture. Just how desperate does one have to be to try to handwave away the entire field and all its evidence by lamely mumbling about "the observer can never be sure..."?
Keep clinging to that if it helps you sleep at night. Meanwhile, the rest of us will keep doing science and adding to the store of tested, reliable, useful human knowledge. You're welcome to keep your eyes closed if it scares you, or uncomfortably challenges some of your favorite preconceptions. But don't try to poison the minds of schoolchildren by filling them with misrepresentations and propaganda and pseudoscience. Most of them want to learn how the Universe *actually* works, not cling to how they'd *like* it to. And those open-minded students who will follow the evidence wherever it leads are the ones who will do great things for humanity someday. Don't stand in their way.