The objectivity of knowledge has been a mainstay of philosophy since forever. The most famous related ancient concept is Plato's Cave (not the most similar one, but a good starting point):
In the allegory, Socrates describes a group of people who have lived chained to the wall of a cave all their lives, facing a blank wall. The people watch shadows projected on the wall from objects passing in front of a fire behind them and give names to these shadows. The shadows are the prisoners' reality, but are not accurate representations of the real world.
Plato's "belief" was that there were multiple higher 'levels' that were increasingly more objective where all things in the real world have an ideal Form or Idea that exists outside our reality. So Plato's explanation would be:
We call both the sky and blue jeans by the same color, blue. However, clearly a pair of jeans and the sky are not the same color; moreover, the wavelengths of light refracted by the sky at every location and all the millions of blue jeans in every state of fading constantly change, and yet we somehow have a consensus of the basic form Blueness as it applies to them. Says Plato:
But if the very nature of knowledge changes, at the time when the change occurs there will be no knowledge, and, according to this view, there will be no one to know and nothing to be known: but if that which knows and that which is known exist ever, and the beautiful and the good and every other thing also exist, then I do not think that they can resemble a process of flux, as we were just now supposing.
Plato believed that long before our bodies ever existed, our souls existed and inhabited heaven, where they became directly acquainted with the forms themselves. Real knowledge, to him, was knowledge of the forms. But knowledge of the forms cannot be gained through sensory experience because the forms are not in the physical world. Therefore, our real knowledge of the forms must be the memory of our initial acquaintance with the forms in heaven. Therefore, what we seem to learn is in fact just remembering.
The valuable thing to note here is that this type of thinking will by necessity touch upon one's beliefs about reality at a very fundamental level. About the relationship between oneself and the reality one may (how can one know there is a reality out there?) inhibit.
Obviously there are many other ideas about the nature of knowledge. This branch of philosophy is called Epistemology and to say it's a 'controversial' field (in the sense that everyone has their own ideas/beliefs) would be an understatement. The idea that one can't know about anything for sure outside the existence of their own mind (closest thing I could think of to what you were describing) would be Solipsism which dates back to a couple of centuries BC and states
Solipsism was first recorded by the Greek presocratic sophist, Gorgias (c. 483–375 BC) who is quoted by the Roman sceptic Sextus Empiricus as having stated:
- Nothing exists.
- Even if something exists, nothing can be known about it.
- Even if something could be known about it, knowledge about it cannot be communicated to others.
Much of the point of the sophists was to show that "objective" knowledge was a literal impossibility.
Which can be a useful starting point in looking at why most people reject this theory. There is no way to directly falsify or reject such a position, but there is solace in the fact that virtually all reject this theory, as at the end of the day there are few (if any) people who just stop interacting with the physical world because they don't believe it exists. So instead the question becomes: "How does one belief that one can derive objective knowledge?". Personally I hold to the idea that there is an unobtainable objective truth 'out there' and all we can do is try to approach it. If you want to explore all the different positions I would recommend just opening https://en.wikipedia.org/wiki/Epistemology#Schools_of_thought_in_epistemology and see you in a couple of years 😅