Dave, Dave, don't be so defensive! I mean, I spend time googling for my name too, but I manage to resist the temptation to throw myself into any discussion of my work, it just comes across badly. I mean, I did go and buy a copy of your book, hardback too, and I did just go and give you a semi-positive review in which I heartily recommended large chunks of it. I really did enjoy quite a lot of it.
You're right, page 4 does mention the idea that a debt is a promise. But it's immediately pooh-poohed as an idea that's "dangerous because it's self-evident". And the last paragraph does call a debt a "promise corrupted by both math and violence", but it's not clear how anything is "corrupted" here. So yeah, you acknowledge this self-evident idea, but only to dismiss it without a proper argument.
Also while you're here (actually yours is exactly the kind of book that I read while wishing that I could argue with the author about certain points, so it really is a privilege to have you here and I hope that doesn't sound like a backhanded compliment), the other point I think you dismiss without enough of a fight is the idea that all human interactions are based on reciprocity. There is of course one counter-example, the child-parent relationship in which the parent is generally happy to give selflessly, but that's a special case which seems to be more-or-less hard-coded into our genes; our minds are programmed to give selflessly to our children since from our genes' point of view they're nearly equivalent to ourselves. Once we step outside the parent-child relationship, however, your other examples of non-reciprocal human behaviour (apart from outright theft, extortion and other forms of behaviour where one party isn't consenting) don't ring true. Two labourers working on the same project will, of course, pass each other hammers, but there is an expectation of reciprocity even in group work, as anyone who has ever worked in a group with someone not pulling their weight will know.
In conclusion, you've written an interesting history of debt, but I think you've started off with some kind of antipathy towards debt which has stopped you from really gaining a good perspective on it. I still don't understand the objection to the basic concept of debt: that if Alice has something and Bob needs it then Alice can lend Bob that thing and get it back in the future, for mutual benefit. I find that to be a glorious example of human interaction at its best. But then again, I've already paid off my mortgage.