The new edition of forall x will be posted soon. Anybody who has used the book before will find the changes so small as to make almost no difference, but I wanted to discuss what I did beyond correcting typos. First, I’ve changed the formatting a bit. Second, I’ve changed the notation for substitution instances in proofs (again). Third, I’ve changed the license to be even more permissive.
It’s been over a decade since I released the first edition of the open access logic textbook forall x. It’s been a few years since my last update, because it’s been a few years since I last taught logic.
A number of people have made their own editions of forall x over the years, but 2017 was a breakout year: Continue reading “A big year, forall x”
[It is a mistake to give] an absolute meaning to the epithet useful, which, in truth, has no more meaning if taken by itself than the words high, low, right, and left. It simply designates a relationship and requires a complement: useful for this or that.
I am teaching Simone de Beauvoir’s Ethics of Ambiguity in my Existentialism class, and I’m struck again by what a great book it is. She elaborates the notion of Bad Faith with much greater clarity than Sartre. There are parts of the book that make me rethink myself and my present situation.
This is striking partly because of context: We spent weeks on Heidegger, who does phenomenology in the most abstract way and only has eyes for metaphysics. Then we spent weeks on Sartre, who dabbles in ethics and has some rich examples but never finds his way around to the ethical question. Sartre writes in Being&Nothingness (in a footnote!) that “the description of [authentic existence] has no place here.”
And now we’re discussing de Beauvoir, whose task is “to consider human life as a game that can be won or lost and to teach… the means of winning.”
The stock example of a semantic tautology is that all bachelors are unmarried. It is supposed to be immediately obvious and necessarily true. It seems to me, however, that it is neither immediately obvious nor necessary.