paratodo x 
A while ago, I was contacted by José Gascón about translating forall x. The open license already gave him permission, but he reached out anyway.

A few days ago, he sent me paratodo x. Because of the spacing of the title, I read this as "paradox" at first. Then I had an uncanny moment of not knowing what that "t" was doing in the middle of the word. Finally, I sorted out what I was looking at.

I think this is a cool resource, so I posted a copy at the UAlbany institutional archive. The LaTeX source files are included, so the Spanish edition can take on a life of its own.

Link: paratodo x: Una Introducción a la Lógica Formal

[ add comment ] ( 309 views )   |  [ 0 trackbacks ]   |  permalink
Other open access logic books 
I realized today that forall x is almost ten years old. I wrote it in the summer of 2005, mostly at the Peet's on Villa La Jolla Drive, and released version 1.0 on July 13 of that year.

I recently heard about A Concise Introduction to Logic, a book that Craig DeLancey of SUNY Oswego is for the OpenSUNY initiative. When they did their call for proposals, forall x wasn't eligible because it had the demerit of already existing!

I learned today about the Open Logic Project, masterminded by Richard Zach (Calgary) with an all-star list of editors and contributors. Unlike forall x, it's an intermediate level book.

Zach and company are using Github to automate bug reports and feature requests, which is an idea I really like. The LaTeX source files of forall x are freely available and it has forked multiple times, but I still maintain the original version on my own computer. I occasionally get corrections and requests, but by e-mail. Alas, I suspect most users of forall x are not the sort of people who would submit corrections and requests that way anyhow.

[ add comment ] ( 675 views )   |  [ 0 trackbacks ]   |  permalink
truth 1, falsity 0 
I just posted version 1.30 of forall x. As usual, the update corrects a number of typos. It also makes some changes. I taught logic this Fall for the first time in several years, and the time away from the book made me realize that some things weren't working as well as they should.

Truth tables

It is standard in philosophy to do truth tables with Ts and Fs, but this makes the shift from sentential logic to quantified logic awkward. The sentential connectives operate in pretty much the same way in a quantified formula as they do in a sentential formula, except that the operators are truth functions in SL and satisfaction functions in QL. I want students to understand the difference between truth and satisfaction, but I also want them to apply what they know about the truth-functional connectives. So I end up saying things like, "Both conjuncts are satisfied, so the conjunction is satisfied. This part's just like in a truth table. Both parts are true, sort of... true-ish... something that works a lot like truth."

In the previous edition of the book, I tried to smooth this over in the chapter on formal semantics by giving the function which defines 'truth in SL' in terms of 1 and 0 rather than in terms of T and F. The definition of 'satisfaction in QL' is also in terms of 1 and 0, and the clauses which define satisfaction for sentential connectives look exactly the same as they do in the definition of truth. So I can say instead, "Both conjuncts are 1, so the conjunction is 1."

The problem is that, by that point, students have acquired habits in terms of T and F from doing truth tables. So I decided to start with 1 and 0 earlier, doing truth tables entirely using 1s and 0s.

This is common in computer science and electronics, even though it's not common in philosophy. My motivation is philosophical, though. Doing truth tables in terms of 1 and 0 underscores the step of abstraction, that these are formal, mathematical values rather than metaphysical truth and falsity. And because they are formal values rather than rich concepts, they can be interpreted differently (as satisfied/not, rather than as true/false).

I think I made this change consistently everywhere, but there are probably still some lingering mention of T and F. New content means new typos.

Proofs in QL

The chapter on proofs is the barest part of the book. It would be the hardest part to learn from directly, if someone were just reading the book rather than taking a course.

In this update, I just made some changes to the presentation of the quantifier rules.

I changed the typographic mark for a substitution instance, and I think it's clearer now. (I won't try to produce it here on the blog.)

I rewrote the Existential Elimination rule so that the proxy constant cannot occur anywhere else in the proof. You have 'Exists x Px' and assume 'Pc' for some entirely new constant c. This is stronger than what's strictly required, but it underscores the conceptual point that c is only functioning as a placeholder name for whatever thing it is that's P. The subproof is the only place where c occurs, because the subproof is the moment in the argument when you say "Something is P. We don't know what, but let's call it c."

I am considering splitting the chapter on proofs into two chapters: One on proofs in SL and another on proofs in QL. This would allow me to add material to both discussions. It would also allow instructors who want to do proofs in SL immediately after doing truth tables to do so more easily. That's not a change I made in this revision, though, and I'm still mulling it over.


I archived earlier versions of the book at a SUNY digital repository. Recently, the library here at UAlbany has set up a local digital repository which should offer more features and more visibility. I think that the submission needs to be approved by a librarian, but version 1.30 will appear there soon enough. Until then, it's available directly from my website.

[ add comment ] ( 1280 views )   |  [ 0 trackbacks ]   |  permalink
Florida and the last mile of logic 
Back in 2007, I opted to change the license for my logic textbook, forall x. The removal of the Non-Commercial provision meant that, since then, people have been allowed to sell copies of the book and of any derivative works they might make. At the time, I wrote this:
There is little danger that a publisher will sell an overpriced deluxe edition of forall x, because the Sharealike provision would preclude them from exercising restrictive rights over it. The content would still be free.

I was perhaps a bit too optimistic.

A while later, a company began selling a poorly made ebook version on Amazon. I wrote a review telling people not to buy it and pointing them to where they can download it for free.

Today I discovered that University Press of Florida is offering forall x for $32.50. They assigned it an ISBN and everything. Their product page does not have any product description at all. If you do a search, though, the description includes information about how to get a copy from Lulu where it's available for $8.50.

They also have the title slightly wrong: "Forall x: Introductory Textbook in Formal Logic" rather than "forall x: An introduction to formal logic"

At the same time, the Senate is considering legislation to support more open licensed textbooks in an effort to make college textbooks affordable. We need to remember that an open license only saves the bit that would be paid to the author. The last mile is getting the text into student hands, which requires not screwing them on printing costs.

UPDATE nov19: I just spoke with someone at UPF. They print the book on-demand for Orange Grove, an imprint which has offered it on Amazon since 2009. So it was already something I knew about, really.

[ add comment ] ( 3341 views )   |  [ 0 trackbacks ]   |  permalink
There's open and then there's "open" 
I was an invited speaker last week at DIY Publishing and the University, an event held by the NorthEast Regional Computing Program. I was there because of forall x; the organizers had found me through the Creative Commons database.

Most of the speakers talked about electronic resources, like institutional archives, student videos, or MOOCs. I was the odd man out, because forall x is a traditional textbook. Although it is distributed electronically, it is designed to be used as a physical workbook. Today I ran across an article in Salon which supports my old-school approach; it argues that people just don't comprehend material read on screen or on a tablet as well as material read on paper. Yet the difference is not so clear or strong that we should imagine it is inevitable. Future students may be better at learning from electronic documents, and future technology might present them in better ways. I will still be teaching a decade or two from now, and my preference for paper may be something I'll need to get over.*

One nice result of the NERCOMP event is that I now have a better understanding of MOOCs. A MOOC (the acronym stands for Massive Open Online Course) allows people from all over the world to register for and take a course. They might watch videos of lectures, participate in a discussion forum with other students, take tests on their computer, and so on. Because the courses are free, they are often mentioned in the same context as open-access textbooks.

The thing I learned is that "open" in MOOC just means open enrollment. Anyone anywhere is free to take the course. The course materials might be released under a Creative Commons license, but they might just be under traditional copyright. MIT labels its MOOC material "some rights reserved" and, although that is a standard label on CC-licensed material, MIT does not specify an specific permissions. Because they don't say, "some" is legally equivalent to "all". The difference is just a flourish, because "all rights reserved" would not sound as welcoming.

So I was also the odd man out because I was one of the few presenters specifically concerned with open access issues.**

* Even if there are cyborg students in the future, though, there are still concerns of equity. Even if it gets to the point where digital natives with advanced e-readers think better with electronic documents than with paper documents, economic disparities will mean that other students don't. Of course, the future of the university as an enterprise is also up for grabs in the next decade or two.
** Not the only one. Thomas Dodson, a librarian from Harvard, talked about their open access repository of faculty research.

[ add comment ] ( 3495 views )   |  [ 0 trackbacks ]   |  permalink

| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | Next> Last>>