
Anthropic posted a FAQ of how their "text watermarking" will work. I don't get it.
So Anthropic posted a FAQ of how their "text watermarking" will work: https://www.anthropic.com/news/claude-text-watermark
I'm not sure I understand how this could possibly work at all, considering that when people use LLM-generated text they are not pasting in the rest of the input and context, so how could it possibly do what they say it does. They do say it has "limitations": > There are limitations to the effectiveness of watermarking. Using our key, one can only answer the question “What is the likelihood this was partly written by Claude?” It doesn’t confirm whether the text was human-written, and it can’t tell whether the text was written by a different AI (even if that other AI uses watermarking, it would have a different key; it might also use a different watermarking method altogether). Detecting a watermark also doesn’t work well on small samples, where there are fewer word choices and thus less information to go on. As a passage increases in length, confidence about Claude’s involvement increases too.
> Watermarking is sparser on factual passages where there are fewer choices that can be made without decreasing the accuracy of the text. For example, take the sentence “Isaac Newton’s most famous work was called Principia…”. It really matters whether the next word is “Mathematica” (it’s the only right answer), so the watermark would have nothing to act on. The same is true for proofreading. If you hand Claude a piece of writing and ask it to edit only the grammar and punctuation and nothing else, the watermark can only live in the handful of corrections, which might be too few to register.
I've also had a quick look at the paper they link to: https://www.nature.com/articles/s41586-024-08025-4
I don't see any discussion of false positive or false negatives. Are they just going to use this tool to claim that Claude is clearly so useful because it will flag everything that anyone writes from now on as Claude-generated?
You can't just say it has limitations without giving it at least some quantitative value.
Maybe someone understands this better and help me get it. Can you really spot a pattern of LLM output given that a model have billions or trillions of weights and we lack the surrounding context? What if I paste the text into the checker and just change a word here and there until it passes?