I’m mulling over a proposal that I write a second edition of my *Introduction to Formal Logic, *first published thirteen years ago by CUP.

I’m tempted. I’m sure I could make a very much better job of it. Though, of course, I’m only too aware of how time consuming it would be to undertake, and I’d also like to crack on e.g. with the *Gentle Introduction* to category theory (which has been going slowly of late).

If I do write a second edition, I’d like to include chapters on natural deduction (Fitch-style, I think, for user-friendliness). But I wouldn’t want the book to get too unwieldy in length — and CUP wouldn’t let it! — so *some* stuff would also have to go. But I guess I could put online some of the current content that goes beyond a usual first logic course (e.g. the completeness proofs for trees for PL and QL!). Would that be a win-win solution? — a tighter book, with the stuff on natural deduction some people wanted, but with the “extras” still available for the small number of real enthusiasts?

I haven’t decided yet whether to take up the proposal, let alone how to reshape and add to the text if I do go with it. But any advice and suggestions (either here, or in emails, address at the end of the About page) — especially from those who have used the first edition or indeed, perhaps even better, from those who decided *not* to use it — will be very gratefully received!

If you were up to doing a bit of renovation at the basement level, you might try augmenting the graph-theoretic picture of propositional calculus. In my own work springing from C.S. Peirce’s logical graphs, I found some efficiency from conceptual and computational points of view could be achieved by passing from trees to cacti, using minimal negation operators as the basic construct. I’m still working on getting all this material in some sort of logical order and I don’t know whether I can post more than one link at a time, so I’ll just start with this one:

☞ Survey of Animated Logical Graphs

I think that doing as you propose (viz., cutting bits and ‘pasting’ them online while adding a bit of natural deduction) would be a win-win.

I like the idea. But here’s an even more onerous suggestion: I think the world needs an “intermediate” logic book. My students found almost everything I tried too hard, with the exception of good old Suppes, but that has its problems (i.e., it’s really sub-intermediate). I have noticed that the computer science field has some books from which I’ve borrowed examples.

What do I have in mind? First-order logic with some proof system or other. Completeness. Then a bunch of simple first-order theories to play with (that’s why I like Suppes). (Groups, fields, alternative axiomatizations, definition, etc. I would like a good axiomatization of string theory.) Lots of induction practice. Lots of practice making proofs into formal derivations. (I suddenly dimly remember that Mates has a some of this, but I remember rejecting it either for oldness or hardness. I should look again. But, a Peter Smith version would be swell.)