GPT recommends I read my own book … which it also claims it wrote

In a recent experiment, I asked GPT-4 if it had written some text, in this case the first two paragraphs of Practical Common Lisp, a book I wrote almost two decades ago and which has been freely available on the web since I wrote it. If you know something about how GPT works you might realize this is not a question it can actually answer. The only correct answer it could give at this point is something along the lines of, “As an AI language model, I do not have a history of all the text I generated so I cannot answer that question.” But it is not in GPT’s nature to admit ignorance when it could instead generate something plausible but wrong.

Let’s see how it goes:

Did you write this?

If you think the greatest pleasure in programming comes from getting a lot done with code that simply and clearly expresses your intention, then programming in Common Lisp is likely to be about the most fun you can have with a computer. You'll get more done, faster, using it than you would using pretty much any other language.

That's a bold claim. Can I justify it? Not in a just a few pages in this chapter--you're going to have to learn some Lisp and see for yourself--thus the rest of this book. For now, let me start with some anecdotal evidence, the story of my own road to Lisp. Then, in the next section, I'll explain the payoff I think you'll get from learning Common Lisp.

GPT very confidently answers that indeed, it had generated this text:

As an AI language model, I generated this text in response to your request. The passage discusses the potential enjoyment and productivity one might experience when programming in Common Lisp. It suggests that the rest of the hypothetical book will provide justification for the bold claim about Common Lisp's benefits, beginning with the author's personal journey and followed by an explanation of the advantages of learning Common Lisp.

When I pressed it, asking what book the text was from, it continued to claim that it had generated the text. Though it was nice enough to recommend that if I wanted a real book I should get the very book it was claiming authorship of.

What book is that text from?

The text I generated is not a direct quote from a specific book but rather a paraphrased, synthesized response based on the context provided in your question. However, the content and the sentiment of the passage resemble the introductory ideas found in some books about learning Lisp or other programming languages. If you are interested in a book about Lisp, one popular option is "Practical Common Lisp" by Peter Seibel.