12 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. |
| 17743 | De Morgan introduced a 'universe of discourse', to replace Boole's universe of 'all things' [De Morgan, by Walicki] |
| Full Idea: In 1846 De Morgan introduced the enormously influential notion of a possibly arbitrary and stipulated 'universe of discourse'. It replaced Boole's original - and metaphysically a bit suspect - universe of 'all things'. | |
| From: report of Augustus De Morgan (works [1846]) by Michal Walicki - Introduction to Mathematical Logic History D.1.1 | |
| A reaction: This not only brings formal logic under control, but also reflects normal talk, because there is always an explicit or implicit domain of discourse when we talk. Of virtually any conversation, you can say what it is 'about'. |
| 12154 | Are 'word token' and 'word type' different sorts of countable objects, or two ways of counting? [Geach, by Perry] |
| Full Idea: If we list the words 'bull', 'bull' and 'cow', it is often said that there are three 'word tokens' but only two 'word types', but Geach says there are not two kinds of object to be counted, but two different ways of counting the same object. | |
| From: report of Peter Geach (Reference and Generality (3rd ed) [1980]) by John Perry - The Same F II | |
| A reaction: Insofar as the notion that a 'word type' is an 'object', my sympathies are entirely with Geach, to my surprise. Geach's point is that 'bull' and 'bull' are the same meaning, but different actual words. Identity is relative to a concept. |
| 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) |
| 8969 | We should abandon absolute identity, confining it to within some category [Geach, by Hawthorne] |
| Full Idea: Geach argued that the notion of absolute identity should be abandoned. ..We can only grasp the meaning of a count noun when we associate it with a criterion of identity, expressed by a particular relative identity sortal. | |
| From: report of Peter Geach (Reference and Generality (3rd ed) [1980]) by John Hawthorne - Identity | |
| A reaction: In other words, identity needs categorisation. Hawthorne concludes that Geach is wrong. Geach clearly has much common usage on his side. 'What's that?' usually invites a categorisation. Sameness of objects seems to need a 'respect'. |
| 16075 | Denial of absolute identity has drastic implications for logic, semantics and set theory [Wasserman on Geach] |
| Full Idea: Geach's denial of absolute identity has drastic implications for logic, semantics and set theory. He must deny the axiom of extensionality in set theory, for example. | |
| From: comment on Peter Geach (Reference and Generality (3rd ed) [1980]) by Ryan Wasserman - Material Constitution 6 | |
| A reaction: I'm beginning to think we have two entirely different concepts here - the logicians' and mathematicians' notion of when two things are identical, and the ordinary language concept of two things being 'the same'. 'We like the same music'. |
| 12152 | Identity is relative. One must not say things are 'the same', but 'the same A as' [Geach] |
| Full Idea: Identity is relative. When one says 'x is identical with y' this is an incomplete expression. It is short for 'x is the same A as y', where 'A' represents some count noun understood from the context of utterance. | |
| From: Peter Geach (Reference and Generality (3rd ed) [1980], p.39), quoted by John Perry - The Same F I | |
| A reaction: Perry notes that Geach's view is in conscious opposition to Frege, who had a pure notion of identity. We say 'they are the same insofar as they are animals', but not 'they are the same animal'. Perfect identity involves all possible A's. |
| 16073 | Leibniz's Law is incomplete, since it includes a non-relativized identity predicate [Geach, by Wasserman] |
| Full Idea: Geach rejects the standard formulation of Leibniz's Law as incomplete, since it includes a non-relativized identity predicate. | |
| From: report of Peter Geach (Reference and Generality (3rd ed) [1980]) by Ryan Wasserman - Material Constitution 6 | |
| A reaction: Not many people accept Geach's premiss that identity is a relative matter. I agree with Wiggins on this, that identity is an absolute (and possibly indefinable). The problem with the Law is what you mean by a 'property'. |
| 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) |