Quote Originally Posted by Segev View Post
Frogreaver, it’s not the literalness of the phrase “who’s to say” that’s the problem. It’s that there is no colloquial way to take it that doesn’t come off insulting when you use it as you did.

The phrase is commonly used only to suggest that what follows has no available authority who could be trusted to provide verifiable knowledge on the subject. Both literally and colloquially, it is not the right phrase to use if you are simply asking for evidence, because both literally and colloquially, it suggests that you don’t know of anybody who has or could be trusted to provide believable evidence.

What I take it you means was something along the lines of, “I don’t know that that’s true; please provide your evidence of that assertion.” This is an entirely different phrase than “who’s to say that’s true?” It accepts the possibility that the person making the assertion might have something to support it. “Who’s to say...?” instead suggests - again, both colloquially and literally - that you don’t trust the speaker to be able to provide evidence to the point that if they try, you wouldn’t trust it. After all, they are not an obvious answer to the question of “who’s to say what you say is true?” if you feel the need to ask the question.

I say this because you’re coming off as potentially much more rude than you mean to, and I suspect (and apologize if I’m mistaken) that either English is not your first language or that you at least don’t know how that phrase is taken in colloquial American parlance. It’s not even that it’s automatically insulting, but used as you did, it always will seem so.

It’s more commonly used in statements like, “Who’s to say there’s no intelligent life on other planets?” It points out that something is unknowable with our current ability to gather evidence, and that we know of no subject matter expert who can believably claim to have sure knowledge.”

That’s not just the literal meaning, but the common usage. There’s no figurative usage that carries a simple request for more information. When used in a context of whether something somebody says about themselves or their activities is true, the only colloquial interpretation is that you’re expressing that you lack sufficient evidence to believe anything that person might say on the subject.

“I’m a PhD in Computer Engineering.” “Who’s to say that you are? Anybody can claim anything on the internet, and even if you showed us your diploma, we can’t trust that you are really the person you’re claiming to be.”

While quite true, this is suggesting that there’s reason to doubt the veracity of the speaker’s personal claims. This can be non-insulting when it’s serious enough. For instance, if someone claims to be a Nigerian Prince, and wants you to make financial decisions based on that, not being willing to take their word is more a matter of safety than anything else. But in a case where the speaker says they’ve done something and proving it is as easy as showing the work, suggesting that there’s no way they can prove it (which is what “who’s to say...?” does) is very insulting. It implies and denotes that you don’t think they are a person who could say whether their claim is true or not with any believable authority.

I say all of this in hopes it helps you with your communication in the future. Using language and idioms to convey what you mean in both implication and decoration is important. And it’s always going to impede communication when you think there exists a figurative colloquial sense in which something is taken, but that colloquial sense doesn’t actually exist.

Ludic Savant isn’t being hyper-literal; you seem to have thought there was a figurative way to take it that doesn’t exist in colloquial English. Thus, it came off as saying, “You’re a lying liar that lies,” and then, when called out on it, your defense is, “stop being so literal. I was just saying that I haven’t seen your proof. I wasn’t really calling you a liar, geeze.” I hope you can see why that would offend people.

I understand you didn’t mean it that way, and I hope this overly-long dissertation on what the phrase means both literally and colloquially helps you better convey your meaning in the future.
We disagree on this.