From the article:

So let me get to the nut of this thing before I do my usual meandering. Recently, someone accused me of using AI to write this old post from about a year ago, specifically highlighting the section about Ta-Nehisi Coates. I replied by saying that the post contained no AI writing; nothing I publish has been written or edited by an LLM. My accuser proceeded to say that the AI detection tool Pangram flagged that portion as 100% AI written with high confidence, a result I replicated. (Pangram report.) As the man who wrote that piece, I knew that I wasn’t guilty, but I also knew that wasn’t going to fly with other people. I was sufficiently annoyed that I paid for a Pangram license and found that, when I entered the entire essay, Pangram cleared it as 100% human written with high confidence. (Pangram report.) That is to say, the essay of about 5,000 words was declared 100% human written with high confidence even though it contains the section of about 300 words which was declared 100% AI written with high confidence. Subsequently, I’ve found that I can produce the same sort of inconsistency in the opposite direction - I can break the section that was called 100% AI into pieces that are then called 100% human written. (Pangram report of an example.) So pieces that Pangram call 100% human written are part of a larger piece that Pangram calls 100% AI written which in turn is part of an essay that Pangram calls 100% human written, a Russian doll of contradictory results.

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The percentage meter seems clearly broken. One frustration of discussing Pangram results is that many people seem to think that the percentage that’s expressed is the confidence level - that is, that a 100% AI result is saying “we are 100% sure that this text is AI generated.” But that’s not what’s being measured there. The percentage is supposed to indicate what portion of the text is suspected to be LLM written. The degree of confidence is flagged there underneath “AI Generated,” although annoyingly the flag only appears when confidence is high, with no “Confidence Low” flag that ever appears, in my experience. This is all fine and good - the percentage AI generated and confidence numbers are different things that should be easy to interpret. The first problem is that many, many people are clearly interpreting “100% AI” to mean “100% confidence.” The second problem is that the percentage meter just does not appear to work! Anecdotally, a really suspiciously high portion of all Pangram outputs are 100%, whether 100% AI or 100% human. This is suspicious not only because a lot of LLM writing that gets published is likely hybrid, integrated with a writer’s own words, but also because the basic processes through which detectors like Pangram function seem likely to produce fewer polar outcomes. And a detector that spits out a lot of 100%s seems easier to break.