Tom Leinster’s Basic Category Theory

9781107044241I just love the opening two sentences of Tom Leinster’s 2014 introductory book, which still seem about as good a minimal sketch of what category theory is up to as you could hope for:

Category theory takes a bird’s eye view of mathematics. From high in the sky, details become invisible, but we can spot patterns that were impossible to detect from ground level.

Taking a bird’s eye view, and thereby seeing better how things hang together, is the sort of intellectual enterprise that appeals to philosophers. Hence — according to me — the interest of category theory  for those interested in the philosophy of mathematics.

I have praised Leinster’s book here before (I think it is terrific, and it worked well with a student reading group of mathematicians last year). The reason for mentioning it again is that he has now, with the kind agreement of CUP, made the book freely available at this arXiv page.

(If you are new here, and this post is of interest, then you’ll also want to look at my category theory page.)

Teach Yourself Logic 2017

The Teach Yourself Logic 2016 Study Guide was viewed an astonishing 51K times and download 3K times from my academia.edu page last year. It was also downloaded another 1.4K times from this Logic Matters site. I guess (or at least, hope!) that some people, somewhere, have found it useful.

Taking a quick look at last year’s version, I haven’t found myself moved to make significant changes right now (partly that’s because my mind, or at any rate the logical bit of it, is so taken up with thinking about IFL2). So the Teach Yourself Logic 2017: A Study Guide (find it on academia.edu by preference, or here) is only a very modest “maintenance upgrade”.

But I must eventually give some thought as to whether it is best to continue with the Guide as a single long document. On the one hand, despite the friendly signposting, 90 pages could seem very daunting. On the other hand, different readers will come with such different backgrounds, interests, and levels of mathematical agility that it is might still seem best just to plot out long routes through the material, all in one place, and (as I do) invite people to get on and off the bus at whatever stops suit them.

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