Category
Possibility & necessity
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Are possible worlds real, or just a bookkeeping device?
David Lewis, in On the Plurality of Worlds (1986), argued that other possible worlds are just as real as ours. "Actual" is indexical, like "here". Our world is actual only in the sense that we are in it. Almost nobody follows him…
Started by Tomasz Szewczak1 reply -
Łukasiewicz, the sea battle, and why three-valued logic was born in Lwów
In De Interpretatione 9 Aristotle considers the sentence "there will be a sea battle tomorrow". If it is already true today, isn't the battle already necessary? And if so, isn't deliberation pointless? Around 1920 Jan Łukasiewicz, working in the Lwów–Warsaw school founded…
Started by Tomasz Szewczak3 replies -
Reading group: Epictetus, Discourses II.19, where the Master Argument meets a bus driver
Epictetus, as people here know by now, is my favourite. Last month a lecture mentioned that the only clear report we have of the "Master Argument" of Diodorus Cronus is at the start of one chapter of his Discourses (the lectures his…
Started by Serkan Aydoğdu5 replies -
Found the Master Argument in Epictetus, between two bus stops
Another find from my recordings. Last week it was Epictetus, Discourses Book 2, and in the middle of a chapter he mentions an argument by Diodorus Cronus that clever people used to show off with. I had to pull my attention back…
Started by Serkan Aydoğdu4 replies -
My daughter asked whether a square circle could exist on another planet. How do I answer?
My nine-year-old has decided that "anything could be true somewhere in space". Last week it was square circles, this week it is a planet where two and two make five. I said no, and she asked why a planet with no gravity…
Started by Thamarai Raman4 replies -
Possibility lives in the powers of real things, not in other worlds
When I look at a plank of cedar I see what it can become: a panel, a frame, a box. That "can" is not in some other world. It is in the cedar: its grain, its weight, the way it takes a…
Started by Hicham Ouazzani5 replies -
The incredulous stare is a perfectly respectable argument against modal realism
I have been reading the threads on Lewis and his infinitely many concrete worlds. I am told the standard response, the "incredulous stare", is not an argument, and that Lewis himself said so. I want to defend the stare. Doctors routinely reject…
Started by Alistair Gow5 replies -
“I could have caught it sooner”: what is a carer’s regret actually claiming?
Something from work that I keep returning to. One of our residents got worse overnight. Looking back, there was a sign at 2 a.m. that, in hindsight, meant he was seriously ill. I noticed it, it didn't seem much, I did not…
Started by Elin Hedqvist5 replies -
If I can conceive it without contradiction, is it possible? Ash’arites, Hume and Kripke
I started reading the Ash'ari theologians to understand occasionalism, and I noticed how much weight they put on one principle: whatever involves no contradiction is possible, at least for God. Al-Ghazali uses it in the Tahāfut when he says the cotton might…
Started by Abdulrahman Al-Bassam5 replies -
S5 is the right logic for metaphysical necessity
Here is a view I hold about modal logic and want tested. S5 says: whatever is possible is necessarily possible, and whatever is necessary is necessarily necessary. In Kripke's terms, every world is accessible from every other. For metaphysical necessity (what could…
Started by Tomasz Szewczak6 replies -
What does Ibn Sina mean by a thing that is “possible in itself, necessary through another”?
I am an architect, not a trained philosopher, so forgive me if this is basic. In reading about Ibn Sina I keep meeting a three-way division: the Necessary Existent in itself, things possible in themselves, and things that are possible in themselves…
Started by Reza Tehrani5 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