15 ideas
| 3067 | A philosopher should have principles ready for understanding, like a surgeon with instruments [Aurelius] |
| Full Idea: As physicians have always their instruments and knives ready for cases which suddenly require their skill, so should you have principles ready for the understanding of things divine and human. | |
| From: Marcus Aurelius (The Meditations (To Himself) [c.170], 3.13) | |
| A reaction: Nice. Philosophy is the training ground where wisdom and good living are made possible, but it cannot be a substitute for living. |
| 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) |
| 3072 | Everything is changing, including yourself and the whole universe [Aurelius] |
| Full Idea: All things are changing; and you yourself are in continuous mutation and in a manner in continuous destruction, and the whole universe too. | |
| From: Marcus Aurelius (The Meditations (To Himself) [c.170], 9.19) |
| 9216 | Each area of enquiry, and its source, has its own distinctive type of necessity [Fine,K] |
| Full Idea: The three sources of necessity - the identity of things, the natural order, and the normative order - have their own peculiar forms of necessity. The three main areas of human enquiry - metaphysics, science and ethics - each has its own necessity. | |
| From: Kit Fine (The Varieties of Necessity [2002], 6) | |
| A reaction: I would treat necessity in ethics with caution, if it is not reducible to natural or metaphysical necessity. Fine's proposal is interesting, but I did not find it convincing, especially in its view that metaphysical necessity doesn't intrude into nature. |
| 9214 | Unsupported testimony may still be believable [Fine,K] |
| Full Idea: I may have good reason to believe some testimony, for example, even though the person providing the testimony has no good reason for saying what he does. | |
| From: Kit Fine (The Varieties of Necessity [2002], 5) | |
| A reaction: Thus small children, madmen and dreamers may occasionally get things right without realising it. I take testimony to be merely one more batch of evidence which has to be assessed in building the most coherent picture possible. |
| 3066 | Nothing is evil which is according to nature [Aurelius] |
| Full Idea: Nothing is evil which is according to nature. | |
| From: Marcus Aurelius (The Meditations (To Himself) [c.170], 2.17) | |
| A reaction: A bit hopeful. Sounds tautological. I.e. anything which is agreed to be evil is probably immediately labelled as 'unnatural'. What would he agree was evil? |
| 3071 | Justice has no virtue opposed to it, but pleasure has temperance opposed to it [Aurelius] |
| Full Idea: In the constitution of the rational animal I see no virtue which is opposed to justice; but I see a virtue which is opposed to pleasure, and that is temperance. | |
| From: Marcus Aurelius (The Meditations (To Himself) [c.170], 8.39) | |
| A reaction: There are plenty of hideous things opposed to justice, but presumably that immediately disqualifies them from being virtues. |
| 3069 | The art of life is more like the wrestler's than the dancer's [Aurelius] |
| Full Idea: The art of life is more like the wrestler's than the dancer's. | |
| From: Marcus Aurelius (The Meditations (To Himself) [c.170], 7.61) |
| 3065 | Humans are naturally made for co-operation [Aurelius] |
| Full Idea: We are made for cooperation, like feet, like hands, like eyelids, like the rows of upper and lower teeth. To act against one another, then, is contrary to nature. | |
| From: Marcus Aurelius (The Meditations (To Himself) [c.170], 2.1) |
| 9215 | Causation is easier to disrupt than logic, so metaphysics is part of nature, not vice versa [Fine,K] |
| Full Idea: It would be harder to break P-and-Q implying P than the connection between cause and effect. This difference in strictness means it is more plausible that natural necessities include metaphysical necessities, than vice versa. | |
| From: Kit Fine (The Varieties of Necessity [2002], 6) | |
| A reaction: I cannot see any a priori grounds for the claim that causation is more easily disrupted than logic. It seems to be based on the strategy of inferring possibilities from what can be imagined, which seems to me to lead to wild misunderstandings. |