11 ideas
| 17884 | Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner] |
| Full Idea: There are many coherent stopping points in the hierarchy of increasingly strong mathematical systems, starting with strict finitism, and moving up through predicativism to the higher reaches of set theory. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], Intro) |
| 17893 | 'Reflection principles' say the whole truth about sets can't be captured [Koellner] |
| Full Idea: Roughly speaking, 'reflection principles' assert that anything true in V [the set hierarchy] falls short of characterising V in that it is true within some earlier level. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 2.1) |
| 17894 | We have no argument to show a statement is absolutely undecidable [Koellner] |
| Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3) |
| 17890 | There are at least eleven types of large cardinal, of increasing logical strength [Koellner] |
| Full Idea: Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable). | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) | |
| A reaction: [I don't understand how cardinals can have 'logical strength', but I pass it on anyway] |
| 17887 | PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner] |
| Full Idea: To the extent that we are justified in accepting Peano Arithmetic we are justified in accepting its consistency, and so we know how to expand the axiom system so as to overcome the limitation [of Gödel's Second Theorem]. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.1) | |
| A reaction: Each expansion brings a limitation, but then you can expand again. |
| 17891 | Arithmetical undecidability is always settled at the next stage up [Koellner] |
| Full Idea: The arithmetical instances of undecidability that arise at one stage of the hierarchy are settled at the next. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) |
| 12699 | A body would be endless disunited parts, if it did not have a unifying form or soul [Leibniz] |
| Full Idea: Without soul or form of some kind, a body would have no being, because no part of it can be designated which does not in turn consist of more parts. Thus nothing could be designated in a body which could be called 'this thing', or a unity. | |
| From: Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.1988), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1 | |
| A reaction: The locution 'soul or form' is disconcerting, and you have to spend some time with Leibniz to get the hang of it. The 'soul' is not intelligent, and is more like a source of action and response. |
| 16776 | Substance is an intrinsic thing, so parts of substances can't also be intrinsic things [Duns Scotus] |
| Full Idea: Substance ...is an ens per se. No part of a substance is an ens per se when it is part of a substance, because then it would be a particular thing, and one substance would be a particular thing from many things, which does not seem to be true. | |
| From: John Duns Scotus (In Praed. [1300], 15.1), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 26.1 | |
| A reaction: The tricky bit is 'when it is a part of a substance', meaning a substance must cease to be a substance when it is subsumed into some greater substance. Maybe. Drops of water? Molecules? Bricks? Cells? |
| 12700 | Form or soul gives unity and duration; matter gives multiplicity and change [Leibniz] |
| Full Idea: Substantial form, or soul, is the principle of unity and duration, matter is that of multiplicity and change | |
| From: Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.1398-9), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 2 | |
| A reaction: Leibniz was a fan of the unfashionable Aristotle, and tried to put a spin on his views consonant with contemporary Hobbesian mechanistic views. Oddly, he likes the idea that 'form' is indestructable, which I don't understand. |
| 12736 | If we understand God and his choices, we have a priori knowledge of contingent truths [Leibniz, by Garber] |
| Full Idea: Insofar as we have some insight into how God chooses, we can know a priori the laws of nature that God chooses for this best of all possible worlds. In this way, it is possible to have genuine a priori knowledge of contingent truths. | |
| From: report of Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.1998-9) by Daniel Garber - Leibniz:Body,Substance,Monad 6 | |
| A reaction: I think it would be doubtful whether our knowledge of God's choosings would count as a priori. How do we discover them? Ah! We derive God from the ontological argument, and his choosings from the divine perfection implied thereby. |
| 12698 | Every body contains a kind of sense and appetite, or a soul [Leibniz] |
| Full Idea: I believe that there is in every body a kind of sense and appetite, or a soul. | |
| From: Gottfried Leibniz (Conspectus libelli (book outline) [1678], A6.4.2010), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1 | |
| A reaction: Note that he never says that there is any intelligence present. This eventually becomes his monadology, but Leibniz is the most obvious post-Greek philosopher to flirt with panpsychism. |