11 ideas
| 5042 | For every event it is possible for an omniscient being to give a reason for its occurrence [Leibniz] |
| Full Idea: Nothing ever takes place without its being possible for one who knew everything to give some reason why it should have happened rather than not. | |
| From: Gottfried Leibniz (Letter on Freedom [1689], p.112) | |
| A reaction: Presumably there will be GOOD reason why genocide occurs. Note that there is a reason for every 'event'. Is there a reason for every truth? Presumably not, or there would have to be reasons for self-evident truths. |
| 17610 | The Axiom of Choice paradoxically allows decomposing a sphere into two identical spheres [Maddy] |
| Full Idea: One feature of the Axiom of Choice that troubled many mathematicians was the so-called Banach-Tarski paradox: using the Axiom, a sphere can be decomposed into finitely many parts and those parts reassembled into two spheres the same size as the original. | |
| From: Penelope Maddy (Defending the Axioms [2011], 1.3) | |
| A reaction: (The key is that the parts are non-measurable). To an outsider it is puzzling that the Axiom has been universally accepted, even though it produces such a result. Someone can explain that, I'm sure. |
| 17620 | Critics of if-thenism say that not all starting points, even consistent ones, are worth studying [Maddy] |
| Full Idea: If-thenism denies that mathematics is in the business of discovering truths about abstracta. ...[their opponents] obviously don't regard any starting point, even a consistent one, as equally worthy of investigation. | |
| From: Penelope Maddy (Defending the Axioms [2011], 3.3) | |
| A reaction: I have some sympathy with if-thenism, in that you can obviously study the implications of any 'if' you like, but deep down I agree with the critics. |
| 17605 | Hilbert's geometry and Dedekind's real numbers were role models for axiomatization [Maddy] |
| Full Idea: At the end of the nineteenth century there was a renewed emphasis on rigor, the central tool of which was axiomatization, along the lines of Hilbert's axioms for geometry and Dedekind's axioms for real numbers. | |
| From: Penelope Maddy (Defending the Axioms [2011], 1.3) |
| 17625 | If two mathematical themes coincide, that suggest a single deep truth [Maddy] |
| Full Idea: The fact that two apparently fruitful mathematical themes turn out to coincide makes it all the more likely that they're tracking a genuine strain of mathematical depth. | |
| From: Penelope Maddy (Defending the Axioms [2011], 5.3ii) |
| 17615 | Every infinite set of reals is either countable or of the same size as the full set of reals [Maddy] |
| Full Idea: One form of the Continuum Hypothesis is the claim that every infinite set of reals is either countable or of the same size as the full set of reals. | |
| From: Penelope Maddy (Defending the Axioms [2011], 2.4 n40) |
| 17618 | Set-theory tracks the contours of mathematical depth and fruitfulness [Maddy] |
| Full Idea: Our set-theoretic methods track the underlying contours of mathematical depth. ...What sets are, most fundamentally, is markers for these contours ...they are maximally effective trackers of certain trains of mathematical fruitfulness. | |
| From: Penelope Maddy (Defending the Axioms [2011], 3.4) | |
| A reaction: This seems to make it more like a map of mathematics than the actual essence of mathematics. |
| 17614 | The connection of arithmetic to perception has been idealised away in modern infinitary mathematics [Maddy] |
| Full Idea: Ordinary perceptual cognition is most likely involved in our grasp of elementary arithmetic, but ...this connection to the physical world has long since been idealized away in the infinitary structures of contemporary pure mathematics. | |
| From: Penelope Maddy (Defending the Axioms [2011], 2.3) | |
| A reaction: Despite this, Maddy's quest is for a 'naturalistic' account of mathematics. She ends up defending 'objectivity' (and invoking Tyler Burge), rather than even modest realism. You can't 'idealise away' the counting of objects. I blame Cantor. |
| 7598 | Zoroaster and the Hebrew prophets evolved different versions of monotheism [Zoroaster, by Armstrong,K] |
| Full Idea: Zoroaster and the Hebrew prophets evolved different versions of monotheism. | |
| From: report of Zoroaster (The Gathas (seventeen hymns) [c.900 BCE]) by Karen Armstrong - A History of God Ch.1 | |
| A reaction: This seems to be the consensus on the origins of monotheism, which places the development much earlier than the appearance of the idea in Greek philosophy. |
| 7472 | Zarathustra was the first to present a god who is an abstract concept [Zoroaster] |
| Full Idea: Zarathustra's achievement was for the first time to present a god who is an abstract concept - he broke with the tradition of a pantheon of gods. | |
| From: Zoroaster (The Gathas (seventeen hymns) [c.900 BCE]), quoted by Peter Watson - Ideas Ch.05 | |
| A reaction: The more abstract the gods become, the harder it is to challenge their existence. |
| 20672 | Zoroastrianism saw the world as a battle between good evil gods [Zoroaster, by Harari] |
| Full Idea: Zoroastrianism saw the world as a cosmic battle between the good god Ahura Mazda and the evil god Angra Mainyu. | |
| From: report of Zoroaster (The Gathas (seventeen hymns) [c.900 BCE]) by Yuval Noah Harari - Sapiens: brief history of humankind 12 'Battle' | |
| A reaction: Hm. This contradicts the impression I had gained that it was monotheist. |