One can't play fast and loose with how language works. Almost all words got their meaning through metaphor as society become more abstract and complex. Just because one doesn't like something doesn't make it less valid.
I get that cradle started out meaning "basket" (like definire started out meaning drawing boundaries), but now it literally also means the place where a civilizations started (like define literally means to describe a word).
Are you denying that process happens? Can words never expand in definition? What about computer terms like type? Can a person never literally type on a computer in any context ever?
Or should I just give up because this is a personal neurological thing that we will just disagree on forever due to differences in how we process inputs about the world?
The difference between "literal" and "figurative"/"metaphorical" is whether a term is being used as a first-order label for a thing in itself, or as a reference to another concept. That is, a figurative use of a term applies meaning by drawing on a distinct source of meaning.
Words (or idiomatic phrases) can become literal when their usage becomes so strongly identified with what they label that their meaning is no longer determined by reference. "Turn on" no longer involves turning, for example.
I agree that "definition" has become literal, because we no longer refer to the concept of boundaries each time we encounter the term. So too with "cradle": we imagine a particular object that isn't a basket, in itself.
I do not believe this is the case when someone calls the Yellow River the cradle of Chinese civilization. I believe that people hearing that term primarily understand "cradle" by reference to the baby-related object, rather than because the word has meaning in itself relating to the start of civilization. As evidence of this, I think attaching "of Chinese civilization" is doing meaningful work, and that most people would be thrown off by the abstract phrase "cradles around the world" or even by the more specific phrase "the Yellow River, China's cradle." They may still understand the speaker's meaning, but they would do so by connecting the metaphorical dots, not because "cradle" has become a literalism.
Let's bring this back to typing because I think it really helps. Typos from Greek refers to a physical mark or impression made by a stamp (not inherently letters, any physical impression). We then used that etymology to come up with 'type' to represent the blocks that deposited ink onto paper . Kind of a stretch, but I would still consider that a first order label in your framework. Great we are aligned.
But wait, I'm typing this comment and there's no physical impressions being made on paper. Am I not literally typing?
>we no longer refer to the concept of boundaries each time we encounter the term. So too with "cradle": we imagine a particular object that isn't a basket, in itself.
Sure, I'm not imagining a printing press, but whether or not I know it, I am making a metaphor to it. So if we stopped using the term 'cradle' to refer to a basket (therefore breaking the metaphor), then cradle becomes literal? Seems like a fragile/not useful distinction to me.
What about my last paragraph? Do you deny that there's a two-step process going on, or do you actually see the phrase "Chinese cradle" and interpret it to mean "birthplace of civilization" rather than first assuming it means a baby-related object produced in China?
Of course it's weak. This is all pedantry. But then again, "literal" now means both "literal" and "not literal" so maybe all linguistic distinctions are fragile. Less useful once they're destroyed, though—it would be nice if we had a word that meant "literal" without also meaning "not literal."
I didn't want to get off topic, but I speculate the most common usage of 'cradle' in American English is 'Cradle to Grave.' I didn't bring it up, since it torpedoes your argument (Cradle is used to mean infancy in this case, not a physical item), but it feels too nuanced to be a general argument.
>it would be nice if we had a word that meant "literal" without also meaning "not literal."
Actually, I think we do.
I think I just factually disagree with you here. I think it would be very rare for a fluent English speaker to hear “cradle of civilization” and need to actually do the work of calling up the concept of a baby bed and make educated guesses about what metaphorical similarities the speaker is trying to evoke.
In fact, in American English I think it’s pretty rare to use “cradle” in informal speech to refer to a baby bed. “Crib” or even “bassinet” or “baby bed” are much more common. “Cradle” is in the lyrics of a well-known lullaby, but to use it in casual speech would be somewhat conspicuous. It’s much more common as a verb, like “cradle the baby in your arms,” which I suspect you would also describe as a metaphorical usage (and I would disagree).
Whether "cradle" is more or less common than "crib" (say) doesn't indicate one way or another whether its usage in other contexts is as a first- or second-order signifier.