Haha what bullshit from Uncle B.
(1) First he says we shouldn't say we know Marion Jones took PEDs because she didn't test positive. (Implying that we could say we "knew" it if there was a positive test.)
(2) Then a few posters discuss the overwhelming evidence for her taking PEDs and Coach Owl Birdo raises the subtle philosophical point that perhaps we shouldn't use the word "know" unless we are 100% certain of something. Therefore we couldn't use "know" even if Marion Jones had tested positive because of the tiny possibility of false positives. A fair point from Coach Own Birdo, but entirely academic. Effectively the word "know" is used in every day parlance different from that. For example, "I know LA is in California." Here I can use the word "know" even if there I am not 100% certain. How can I be 100% certain? I've never been there.)
(3) Uncle B then pretends that he was actually making the same point that Coach Owl Birdo was making. This is clearly not the case because of (1). Uncle B also somehow implies that it is right wingers who are guilty of using "know" incorrectly, which is not the point Coach Own Birdo was making anyway.
(4) Then Uncle B says it is 100% true that Israel has detained over 12000 Palestinians without charges. How can he know this with this degreee of certainty? Of course he can't, showing that he doesn't even understand the point Coach Owl Birdo made.
What lack of clarity and poorly constructed arguments!