So knowledge is subjective? I thought we knew that already.
This is a very interesting question. How do we distinguish knowledge from belief? Others in this thread have gone back to the traditional philosophical position that knowledge is justified belief, but there are lots of beliefs we have justification for that we do not "know". For example, you may think you "know" who your biological parents are, because you never had a reason to suspect otherwise. Then one day, you may come to learn as my grandmother did that those were not your biological parents. My great grandparents had suffered a tragic death, and an aunt raised my grandmother in ignorance of the facts until her grandfather died and left her some money. Then the truth came out.
Now, it would have been true for her to say that she knew who her biological parents were until she learned the real truth. Then she could not say truthfully that she had known her biological parents as a child. Did she ever suddenly cease to know who her real parents were? Well, there was a brief period of confusion, but basically, she always believed she knew who they were. It's just that her belief changed at some point and she could no longer truthfully utter the statement "I knew who my parents were as a child". Ironically, she always did know who her true biological grandparents were.
And that is the crux of the matter that most of the philosophers have missed historically. Knowledge has to do with what the person who reports the belief believes. That is, "know" reports a belief that the speaker of an utterance believes to be true, not necessarily what actually is true. In linguistic terms, we call the speaker's belief a
presupposition. Presuppositions are believed true by the speaker regardless of whether the reported belief is positive or negative or unknown. Hence, the following three sentences can only be uttered felicitously by someone who believes that God exists:
"John knows that God exists."
"John does not know that God exists."
"Does John know that God exists?"
Replace "know" with "believe" in the above sentences, and the "speaker" presupposition disappears. The speaker could be either a theist or an atheist.
And now some of you should know something more about "knowledge". It tells you something about the beliefs of an independent observer (the "speaker") that reports a belief. What counts as "justified belief" is not always knowledge.