10 ideas
| 22304 | Truth is conceivability, or the systematic coherence of a significant whole [Joachim] |
| Full Idea: Truth is in its essence conceivability or systematic coherence. ...[p.78] It is the systematic coherence which characterises a significant whole. | |
| From: Harold Joachim (The Nature of Truth [1906], p.68), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 35 'coh' | |
| A reaction: We obviously need to know when a whole becomes 'significant'. Potter says mystical idealists liked this because it contributed to their teleological view of the whole of reality. Presumably its roots are in Hegel. |
| 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. |
| 20076 | An intending is a judgement that the action is desirable [Davidson] |
| Full Idea: We can identify an intentional action ...with an all-out conditional judgement that the action is desirable. ...In the case of pure intending, I now suggest that the intention simply is an all-out judgement. | |
| From: Donald Davidson (Intending [1978], p.99), quoted by Rowland Stout - Action 8 'Davidson's' | |
| A reaction: 'Pure' intending seems to be what Stout calls 'prior' intending, which is clearer. This still strikes me as obviously false. I judge that it is desirable that I make a cup of coffee, but secretly I'm hoping someone else will make it for me. |
| 20024 | Davidson gave up reductive accounts of intention, and said it was a primitive [Davidson, by Wilson/Schpall] |
| Full Idea: Later Davidson dropped his reductive treatment of intentions (in terms of 'pro-attitudes' and other beliefs), and accepted that intentions are irreducible, and distinct from pro-attitudes. | |
| From: report of Donald Davidson (Intending [1978]) by Wilson,G/Schpall,S - Action 2 | |
| A reaction: Only a philosopher would say that intentions cannot be reduced to something else. Since I have a very physicalist view of the mind, I incline to reduce them to powers and dispositions of physical matter. |