17 ideas
| 1564 | True and false statements can use exactly the same words [Anon (Diss)] |
| Full Idea: There is no difference between a true statement and a false statement, because they can use exactly the same words. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §4) |
| 9944 | We understand some statements about all sets [Putnam] |
| Full Idea: We seem to understand some statements about all sets (e.g. 'for every set x and every set y, there is a set z which is the union of x and y'). | |
| From: Hilary Putnam (Mathematics without Foundations [1967], p.308) | |
| A reaction: His example is the Axiom of Choice. Presumably this is why the collection of all sets must be referred to as a 'class', since we can talk about it, but cannot define it. |
| 9937 | I do not believe mathematics either has or needs 'foundations' [Putnam] |
| Full Idea: I do not believe mathematics either has or needs 'foundations'. | |
| From: Hilary Putnam (Mathematics without Foundations [1967]) | |
| A reaction: Agreed that mathematics can function well without foundations (given that the enterprise got started with no thought for such things), the ontology of the subject still strikes me as a major question, though maybe not for mathematicians. |
| 9939 | It is conceivable that the axioms of arithmetic or propositional logic might be changed [Putnam] |
| Full Idea: I believe that under certain circumstances revisions in the axioms of arithmetic, or even of the propositional calculus (e.g. the adoption of a modular logic as a way out of the difficulties in quantum mechanics), is fully conceivable. | |
| From: Hilary Putnam (Mathematics without Foundations [1967], p.303) | |
| A reaction: One can change the axioms of a system without necessarily changing the system (by swapping an axiom and a theorem). Especially if platonism is true, since the eternal objects reside calmly above our attempts to axiomatise them! |
| 9940 | Maybe mathematics is empirical in that we could try to change it [Putnam] |
| Full Idea: Mathematics might be 'empirical' in the sense that one is allowed to try to put alternatives into the field. | |
| From: Hilary Putnam (Mathematics without Foundations [1967], p.303) | |
| A reaction: He admits that change is highly unlikely. It take hardcore Millian arithmetic to be only changeable if pebbles start behaving very differently with regard to their quantities, which appears to be almost inconceivable. |
| 9941 | Science requires more than consistency of mathematics [Putnam] |
| Full Idea: Science demands much more of a mathematical theory than that it should merely be consistent, as the example of the various alternative systems of geometry dramatizes. | |
| From: Hilary Putnam (Mathematics without Foundations [1967]) | |
| A reaction: Well said. I don't agree with Putnam's Indispensability claims, but if an apparent system of numbers or lines has no application to the world then I don't consider it to be mathematics. It is a new game, like chess. |
| 9943 | You can't deny a hypothesis a truth-value simply because we may never know it! [Putnam] |
| Full Idea: Surely the mere fact that we may never know whether the continuum hypothesis is true or false is by itself just no reason to think that it doesn't have a truth value! | |
| From: Hilary Putnam (Mathematics without Foundations [1967]) | |
| A reaction: This is Putnam in 1967. Things changed later. Personally I am with the younger man all they way, but I reserve the right to totally change my mind. |
| 1559 | Thracians think tattooing adds to a girl's beauty, but elsewhere it is a punishment [Anon (Diss)] |
| Full Idea: Thracians think that tattooing enhances a girl's beauty, whereas for everyone else tattooing is a punishment for a crime. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §2) |
| 1561 | Anything can be acceptable in some circumstances and unacceptable in others [Anon (Diss)] |
| Full Idea: Anything can be acceptable under the right circumstances, and unacceptable under the wrong circumstances. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §2) |
| 1560 | Lydians prostitute their daughters to raise a dowery, but no Greek would marry such a girl [Anon (Diss)] |
| Full Idea: The Lydians find it acceptable for their daughters to work as prostitutes to raise money for getting married, but no one in Greece would be prepared to marry such a girl. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §2) |
| 1389 | If memory is the sole criterion of identity, we ought to use it for other people too [Shoemaker] |
| Full Idea: If memory were the sole criterion of personal identity it would have to be the sole criterion that we use in making identity statements about persons other than ourselves. | |
| From: Sydney Shoemaker (Personal Identity and Memory [1959], §4) | |
| A reaction: From Locke's point of view, he is much less certain about the continued identity of other people, because he allows the possibility of transference of minds. Even we might reject physical identity, if a person had suffered a severe trauma. |
| 1390 | Bodily identity is one criterion and memory another, for personal identity [Shoemaker, by PG] |
| Full Idea: Bodily identity must be one of the criteria for personal identity (to establish that a rememberer was present at a past event), but memory itself must also be accepted as one of the criteria. | |
| From: report of Sydney Shoemaker (Personal Identity and Memory [1959], §5) by PG - Db (ideas) | |
| A reaction: This concerns the epistemology of personal identity, not the ontology. Someone with total amnesia would probably accept a driving licence as a criterion. Is personal identity a mental state, or a precondition which makes mental states possible? |
| 1567 | How could someone who knows everything fail to act correctly? [Anon (Diss)] |
| Full Idea: If someone knows the nature of everything, how could he fail to be able also to act correctly in every case? | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §8) |
| 1563 | Every apparent crime can be right in certain circumstances [Anon (Diss), by PG] |
| Full Idea: It can be right, in certain circumstances, to steal, to break a solemn promise, to rob temples, and even (as Orestes did) to murder one's nearest and dearest. | |
| From: report of Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §3) by PG - Db (ideas) | |
| A reaction: Not sure about the last one! I suppose you can justify any hideousness if the fate of the universe depends on it. It must be better to die than the perform certain extreme deeds. |
| 1562 | It is right to lie to someone, to get them to take medicine they are reluctant to take [Anon (Diss)] |
| Full Idea: It is right to lie to your parents, in order to get them to take a good medicine they are reluctant to take. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §3) | |
| A reaction: I dread to think what the medicines were which convinced the writer of this. A rule such as this strikes me as dangerous. Justifiable in extreme cases. House on fire etc. |
| 1566 | The first priority in elections is to vote for people who support democracy [Anon (Diss)] |
| Full Idea: A lottery is not democratic, because every state contains people who are not democratic, and if the lottery chooses them they will destroy the democracy. People should elect those who are observed to favour democracy. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §7) |
| 1565 | We learn language, and we don't know who teaches us it [Anon (Diss)] |
| Full Idea: We learn language, and we don't know who teaches us it. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §6) |