All topics
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If syllogistic logic couldn’t handle relations, why did it last two thousand years?
Working inside predicate logic every day, I'm often reminded how much it can do that the syllogism can't. The textbook example (usually credited to De Morgan) is: all horses are animals, therefore every head of a horse is the head of an…
Started by Derek Hollis6 replies -
Qiyās, kal va-chomer and legal analogy: defeasible reasoning with centuries of rules
The reasoning I heard most often from the bench, in all my years in court, was neither deduction nor statistics. It was analogy: this case resembles that one in the respect that matters, so it should be decided the same way. Islamic…
Started by Khalid Mahmood Awan5 replies -
Fuzzy logic is good engineering and a poor theory of vagueness
I've shipped fuzzy controllers. They work, they're cheap, and nobody who has used a decent one doubts that. My thesis is narrower: as an account of what vague words mean, fuzzy logic doesn't solve the problem it's usually advertised as solving. Two…
Started by Derek Hollis4 replies -
Did Epicurus actually make the argument from evil that carries his name?
In my theology seminar the lecturer put up the famous dilemma, "Is God willing to prevent evil but not able? Then he is not omnipotent. Able but not willing? Then he is malevolent...", with "Epicurus" printed under it. A friend in classics…
Started by Aoife Kilbride4 replies -
Reading group: David Lewis, On the Plurality of Worlds (1986), chapters 1–4
Most people meet modal realism as a punchline: the man who believed every possible world is as real as ours. I want to read the book properly, because the argument is far better than its reputation, and because I think most of…
Started by Tomasz Szewczak6 replies -
Reading group: Pascal’s wager fragment and the pages around it, in French and English
I translate for a living, and Pascal is one of the writers whose sentences I envy most. The wager is usually taught as a three-line argument in a table. In the Pensées it is a long, broken, urgent fragment, and the context…
Started by Claire Dubois6 replies -
How did Kripke’s possible worlds turn S4 and S5 from arbitrary axioms into something meaningful?
I've been reading about modal logic for fun. I understand the operators. What I don't understand is the history I keep seeing summarised: C. I. Lewis invented several systems, S1 to S5, with different axioms; nobody could say which was "correct" or…
Started by Pieter van Dijkhuizen4 replies -
An infinite chain of reasons is not a defect: the case for infinitism deserves more than a smirk
When students first meet the regress problem they are told there are three options and one of them is obviously absurd. Foundations, coherence, or an infinite regress; and who could believe in an infinite regress? I want to argue that infinitism, defended…
Started by Tomasz Szewczak5 replies -
Reading group: Tarski’s “The Semantic Conception of Truth” (1944) in three sittings
Tarski's technical work on truth is hard going, but in 1944 he wrote a non-technical paper for Philosophy and Phenomenological Research that explains the ideas for philosophers. It is clear, polemical in places, and only thirty-odd pages. I propose we read it…
Started by Tomasz Szewczak6 replies -
Reading group: Quine’s ‘On What There Is’, slowly, in three sittings
"On What There Is" first appeared in the Review of Metaphysics in 1948 and opens From a Logical Point of View (1953). It is short, funny in places, and much quoted by people who have not read it. I propose we read…
Started by Tomasz Szewczak6 replies -
Reading group: Stoic logic in Diogenes Laertius, Lives Book VII
Chrysippus is said to have written hundreds of books, a large share of them on logic, and almost all are lost. What we have of Stoic logic comes mostly through later writers: Diogenes Laertius, who gives a summary of Stoic dialectic in…
Started by Giulia Ferrante5 replies -
Reading group: Nagel’s bat, Chalmers’s hard problem and Dennett’s case against qualia
I write formal-verification tools for a living, and I like threads where the argument can be pinned down. Consciousness is the place where that's hardest, so let's read three short classics together, in the order that shows the debate developing. Week 1.…
Started by Derek Hollis5 replies