The second edition of my An Introduction to Formal Logic was originally published by CUP. It is now exactly two years ago today that I was able to make the book free to download as a PDF and also make it available as a very cheap paperback, thanks to the Amazon print-on-demand system. How have things gone?
As with the Gödel book I really didn’t know what to expect. But from almost the beginning, IFL2 has been downloaded about 850 times a month, and has sold very steadily over 75 paperbacks a month (with numbers if anything creeping up). Which, on the one hand, isn’t exactly falling stone-dead from the press. But, on the hand, given the very large number of philosophy students who must be taking Logic 101 out there in the Anglophone world, it isn’t an overwhelming endorsement either. However, you can’t please everyone: there isn’t much consensus about what we want from an intro logic book (which is why unwise lecturers like me keep spending an inordinate amount of time writing our own, despite the best advice of our friends …). Modified rapture, then.
So what now? IFL1 was truth-tree based. IFL2 uses a Fitch-style natural deduction system. The intro book I’d ideally write would cover both trees and natural deduction. That wasn’t possible within the CUP page budget. But those constraints are lifted. A PDF can be as long as I want; and in fact the marginal additional printing cost of expanding the paperback by fifty or sixty pages wouldn’t make very much difference to the price. So an expanded IFL3 is certainly a possibility. But do I actually want to write a third edition?
OK, I confess I’m tempted! Not at all because I think the world stands in desperate need of such a book, but because (very sad to relate) I’d actually rather enjoy the exercise of getting things into the best shape I can, before I hang up my expository boots. A plan for 2023? If the gods are willing.
I would have kept the two editions of the book as separate versions. The tree method is so fun to teach and it can be given relatively simple soundness and completeness proofs.
But I think one reason for why the book is not more widely adopted than it is has to do with its length. As a teacher I would prefer a shorter text that not only could it be covered in a 10 week semester, but I also would want to make sure that, say, some barely out of high school freshmen students, or let’s fact is, humanities students in general, would not be put off by its length.
I do take the point. Even if a book is provided with one of those initial maps which says “Follow this path if you want a bare bones intro, follow that path if you want a more substantial tree-based course, follow this other path if you want an ND-based course, …”, sheer length can be off-putting/daunting. So one thing I’ll be turning over at the back of my mind while getting on with other things is what the happiest solution might be ….