Both halves of the sentence contain wrong and rendundant statements. Since truth is a relation of correspondence between a proposition and reality and knowledge is justified true belief or it is not knowledge; it is both impossible for us to know untruths if we believe them to be true (we can believe falsehoods but we can only know truth), and likewise truths, being essentially propositions, cannot not be known (can only be known by someone, or there is no one proposing them therefore no truth relation subsists - ergo no 'truth' can be wholly unknown to everyone.)
You may say instead:
A lot we believe is not true, and we don't know much.
Actual reality and Truth are the same thing. Because two parties cannot agree on what they perceive the Truth to be does not imply it doesn't exist. In fact, both parties could be wrong - Truth could be a 3rd thing both are oblivious to.
I think they meant what is true, which is also concrete, technical and unambiguously defined in this setting. But you are very correct to make the distinction between truth and knowledge. Pointing out that many philosophers have believed that knowledge is justified true belief might elucidate the relationship a bit.
Actually, it's literally impossible to know something that isn't true. Plato defined knowledge as "true justified belief", which is an imperfect definition but good enough for our purposes.
> Nothing is purely true or false because everything falls on a continuum.
That statement sure isn't purely true. (Therefore, there must at least kind of be something which is either purely true or purely false.) Though perhaps the sentiment behind it might not be totally wrong?
There is truth - sometimes we just don't know what it is. But that means we can talk about the truth of A claiming X because of (...) and B claiming Y because of (...). (this is basically what every real research paper is - claims and their justifications, not "truth") There's nothing good about the defeatism and saying "well, we'll never know, just ignore it".
Truth cannot be out there—cannot exist independently of the human mind—because sentences cannot so exist, or be out there. The world is out there, but descriptions of the world are not. Only descriptions of the world can be true or false. The world on its own—unaided by the describing activities of humans—cannot.
-- Richard Rorty
The point is not that the world does not behave in consistent ways: the point is that if you assume there is some objective truth 'out there', you are bound to sometimes end up with 'wrong' conclusions, because truth is only in us, because 'truth' is not an attribute that 'what is out there' has.
>You imply that there is such thing as absolute fact or absolute truth. Which is not the case unfortunately
Is this not an absolute fact or an absolute truth? You're making an absolute universal claim even though you just rejected the notion of a absolute universal fact.
> If everything that one person chooses to believe is true for them, and that person chooses to believe that there is an objective truth that precludes this statement, then you have a problem.
I can't parse this sentence at all -- mostly, I think, because "true for them" doesn't seem to mean anything. Can you clarify? Also, what's the problem you're talking about?
> I've slowly been converging upon the belief that there's no such thing as "truth". There are only models and predictions, and some models lead to better predictions than other models. (What then is a mathematical truth?)
This seems like saying, "The truth is that there is no truth." Or the truth is that there is a set of models which are more or less the case and this meta-model is the actual truth. In both cases, the argument seems to implicitly rest upon the truth, or a belief of the nature of truth without getting out from under the thing that the argument attempts to deny. How can we talk about there being no such thing as truth without it turning into a sentence like:
> There is no universal truth as the author seems to imply.
Indeed not, but to use the coined term, some things are truthier than others. By and large, we can make more informed and better decisions on the "truthiest" truths without mucking up the argument with individual, pointless anecdotes, especially when those anecdotes aren't backed by anything but what simply "happened" to them.
You may say instead: A lot we believe is not true, and we don't know much.
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