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.

Archiving


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.

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Books about kinds 
I met Muhammad Ali Khalidi in Paris last Spring. I had regrettably only taken the most cursory of glances at his book, Natural categories and human kinds. The library here had just gotten a copy, so 'just' that it wasn't processed and available for checkout until after I got back.

So I checked it out and took a more careful look at it when I returned. Over the summer, I was invited to write a review for Studies in History and Philosophy of Biological and Biomedical Sciences. This provided me a copy of my own and an occasion to think more about his view.

I was asked to write a longish essay review which both evaluated the book and connected it to broader issues that I think are important. I have am already on record as to what I think is important about natural kinds, so I use the review to distinguish MAK's view from mine and to argue briefly for my own way of doing things. It's a review and a critical notice all in one, at once other-directed and self-indulgent.

I sent my last draft off to the journal and posted it: Epistemic categories and causal kinds

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Two papers from late summer 
In the waning days of summer, before the semester started, I finished up two draft papers. I neglected to actually link to them however, an oversight which I now remedy.


How to be a realist about natural kinds
Abstract: Laura Franklin-Hall argues for a nuanced anti-realism about natural kinds. In the course of her argument, she considers the accounts offered by Richard Boyd and me to be alternative anti-realist views. But Boyd and I are both avowed realists about natural kinds. There is an important presupposition hidden in the way that Franklin-Hall poses the problem, namely that a real natural kind must be natural simpliciter. Boyd and I take naturalness to be a relation between a kind and a domain and, because we do not accept a presupposition of the question, are neither realists nor anti-realists in Franklin-Hall's sense. Nevertheless, there is another important sense in which domain-specificity is compatible with realism.


What kind of is-ought gap is there and what kind ought there be?
with Jon Mandle
Abstract: Some philosophers think that there is a gap between is and ought which necessarily makes normative enquiry a different kind of thing than empirical science. We argue that there is no categorical answer as to whether there is or is not. The question of an is-ought gap is practical and strategic matter rather than a logical one, and it might be answered in different ways for different questions or at different times.

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Twitter buzz 
My department has a widget on its homepage which lists recent department news, and I came in today to find that something had broken in the string of tin cans which I had relied upon turn the Facebook feed to RSS to Javascript to a news box. So the other things I had to do got put on hold while I tried to unbreak our website.

After some searching, I gave up on finding a solution that mirrors the Facebook feed. The same information, more or less, is posted to Twitter. And Twitter provides widgets for mirroring feeds.

However, actually getting one of the Twitter widgets required registering for Twitter. So I did. I had no interest in having a Twitter account for actually tweeting, but whatever.

Almost immediately, I got a notification that someone I know is now following me on Twitter.

[Insert hold music: dum dah dum, doo doo]

I got distracted mid rant. Returning to finish the post, I realized that I might actually prefer Twitter to social microblogging alternatives like posting on Facebook or Google+.

Twitter posts are in many ways like tiny webpages: You can get at them with third-party clients. They are public things that you can link to. You can aggregate or sort them in different ways.

Those are things which are good about the web.

Facebook posts and comments, in contrast, are kept inside Facebook's private garden. You can't link to them. You're at the mercy of Facebook's interface. And Facebook will filter what you and others see in whatever ways they decide to use for now.

So maybe I should use my Twitter account.

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Mill still and again 
My second paper on JS Mill and natural kinds was written with the working title "Let a Millian flower bloom". Ultimately, I decided that it needed a more informative title. So it will be presented under another a title and published under a third.

I'll be giving a version as a talk at the PSA in November under the title "What the 19th century knew about natural kinds and the 20th forgot".

And the fully developed paper has been accepted for publication in HOPOS under the title "John Stuart Mill on taxonomy and natural kinds".

A late-stage draft is available on my website.

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