If we say "All swans are white", but don't know there are black swans, is our claim true or false?

(Ignoring the black swan…)
This is where scientists get themselves in trouble. The scientist would say ” My current data indicates all swans are white.” Or, “To date we have only found white swans.” Most people fall asleep by the time the sentence is finished. they think the scientist is not sure.
Meanwhile a less careful blow hard can yell in a loud voice.“All swans are white.” and most people would believe it.
There is a lesson there somewhere.

The claim is false, but it’s not a lie. Lies involve willing deception.

A lie is a statement that you know is false. Therefore it is not a lie since you believe it is true.

There is an interesting type of statement that tests the notion of what is a lie. What are we to make of statements where the speaker does not know nor care whether the statement is true? The philosopher Harry Frankfurt calls these BS. I can think of a prominent political figure who is prone to making such statements.

The black swan example is often used to show how scientific method works. A scientific statement is one that can be tested by experiment to see if it is true If the experiment works then the hypothesis is accepted provisionally until such time that it may be contradicted. One counter-example makes the hypothesis false. A scientist who only knew of white swans might conjecture that all swans are white. Once a single black swan is found, the hypothesis has been shown to be false.

The statement is “true” (as truth is a mutable, philosophical, subjective, concept) but not factual.

Well, this is apt:

“Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science.”
― Charles Darwin, The Descent of Man

And there’s more where that came from.

This is a great question for a Monday morning – or any other, for that matter. Or any time at all.

The problem with the statement, though, or with any statement one can make, is that “the more you know, the less you can be sure of”. Because as @LuckyGuy notes, you can believe yourself to be correct in a statement because of limited knowledge and insufficient qualifiers – but that doesn’t make you “right”. And you can be in the camp of “97% consensus”, to call a number out of thin air, but if the 97% aren’t correct in their statements, their qualifiers and their own understanding, then they aren’t right, either.

Even the statement in the OP is not “quite” correct, because we could more properly say that “truth IS reality”, and while a “true statement” may correspond to reality, it’s probably not possible to find “truth” in words, because of so many factors, starting with the impossibility that any two people can agree on the exact definitions of the words, and continuing through the differences that occur in our own minds in processing the definitions and meanings and simply hearing or seeing the words themselves. There’s no “truth” in a statement (even this one) beyond the closest approximation of reality.

And there’s a lot of uncertainty in our perception of reality, before we even start to speak of it.

I’d answer but @LuckyGuy beat me to the punch almost verbatim.

False. Ignorance is not always bliss.

All swans are ducks who suffered mass dislocated necks due to having their heads pulled out of the water by their frantic parents upon their very first swimming lesson.

^What if there are swans that aren’t ducks, or have had nice parents, but you didn’t know about that?

Do I have legitimate right to call you a liar now or not?

A parent trying to save their offspring from drowning deserves to be called nice at the very least.
I do have the legitimate right to call you a dunderhead now, no question :D

@ucme I accept my new title.