17 ideas
| 13949 | All models of Peano axioms are isomorphic, so the models all seem equally good for natural numbers [Cartwright,R on Peano] |
| Full Idea: Peano's axioms are categorical (any two models are isomorphic). Some conclude that the concept of natural number is adequately represented by them, but we cannot identify natural numbers with one rather than another of the isomorphic models. | |
| From: comment on Giuseppe Peano (Principles of Arithmetic, by a new method [1889], 11) by Richard Cartwright - Propositions 11 | |
| A reaction: This is a striking anticipation of Benacerraf's famous point about different set theory accounts of numbers, where all models seem to work equally well. Cartwright is saying that others have pointed this out. |
| 18113 | PA concerns any entities which satisfy the axioms [Peano, by Bostock] |
| Full Idea: Peano Arithmetic is about any system of entities that satisfies the Peano axioms. | |
| From: report of Giuseppe Peano (Principles of Arithmetic, by a new method [1889], 6.3) by David Bostock - Philosophy of Mathematics 6.3 | |
| A reaction: This doesn't sound like numbers in the fullest sense, since those should facilitate counting objects. '3' should mean that number of rose petals, and not just a position in a well-ordered series. |
| 17634 | Peano axioms not only support arithmetic, but are also fairly obvious [Peano, by Russell] |
| Full Idea: Peano's premises are recommended not only by the fact that arithmetic follows from them, but also by their inherent obviousness. | |
| From: report of Giuseppe Peano (Principles of Arithmetic, by a new method [1889], p.276) by Bertrand Russell - Regressive Method for Premises in Mathematics p.276 |
| 15653 | We can add Reflexion Principles to Peano Arithmetic, which assert its consistency or soundness [Halbach on Peano] |
| Full Idea: Peano Arithmetic cannot derive its own consistency from within itself. But it can be strengthened by adding this consistency statement or by stronger axioms (particularly ones partially expressing soundness). These are known as Reflexion Principles. | |
| From: comment on Giuseppe Peano (Principles of Arithmetic, by a new method [1889], 1.2) by Volker Halbach - Axiomatic Theories of Truth (2005 ver) 1.2 |
| 17635 | Arithmetic can have even simpler logical premises than the Peano Axioms [Russell on Peano] |
| Full Idea: Peano's premises are not the ultimate logical premises of arithmetic. Simpler premises and simpler primitive ideas are to be had by carrying our analysis on into symbolic logic. | |
| From: comment on Giuseppe Peano (Principles of Arithmetic, by a new method [1889], p.276) by Bertrand Russell - Regressive Method for Premises in Mathematics p.276 |
| 3523 | Shadows are supervenient on their objects, but not reducible [Maslin] |
| Full Idea: Shadows are distinct from the physical objects casting the shadows and irreducible to them; any attempt at reduction would be incoherent, as it would entail identifying a shadow with the object of which it is a shadow. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 6.3) | |
| A reaction: Another failure to find a decent analogy for what is claimed in property dualism. A 'shadow' is a reification of the abstract concept of an absence of light. Objects lose their shadows at dusk, but the object itself doesn't change. |
| 3517 | 'Ontology' means 'study of things which exist' [Maslin] |
| Full Idea: The word 'ontology' is derived from the Greek word 'ontia', which means 'things which exist'. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 1.1) |
| 3538 | Analogy to other minds is uncheckable, over-confident and chauvinistic [Maslin] |
| Full Idea: The argument from analogy makes it impossible to check my inductive inferences because of the privacy of other minds; it also seems irresponsible to generalise from a single case; and it seems like a case of human chauvinism. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 8.2) | |
| A reaction: Privacy of other minds need not imply scepticism about them. I'm a believer, so I have no trouble checking my theories. Solipsists can't 'check' anything. It isn't 'irresponsible' to generalise from one case if that is all you have. |
| 3540 | If we are brains then we never meet each other [Maslin] |
| Full Idea: If I am my brain this leads to the odd result that you have never met me because you have never seen my brain. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 10.7) | |
| A reaction: 'Star Trek' is full of aliens who appear beautiful, and turn out to be ugly grey lumps. 'I am my face' would be just as odd, particularly if I were in a coma, or dead. |
| 3518 | I'm not the final authority on my understanding of maths [Maslin] |
| Full Idea: I may be the final authority on whether my shoe pinches, but I am manifestly not the final authority on whether I understand some mathematical theorem. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 1.7) | |
| A reaction: However, it doesn't follow that his teachers are the final authority either, because he may get correct answers by an algorithm, and bluff his way when demonstrating his understanding. Who knows whether anyone really understands anything? |
| 3530 | Denial of purely mental causation will lead to epiphenomenalism [Maslin] |
| Full Idea: If mental events are causally efficacious only by virtue of their physical features and not their mental ones, …then anomalous monism leads straight to ephiphenomenalism. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 7.6) | |
| A reaction: As epiphenomenalism strikes me as being incoherent (see Idea 7379), what this amounts to is that either mental effects are causally efficacious, or they are not worth mentioning. I take them to be causally efficacious because they are brain events. |
| 3520 | Token-identity removes the explanatory role of the physical [Maslin] |
| Full Idea: In token-identity mental and physical features seem as unrelated as colour and shape, which is very weak physicalism because it does not allow physical states an explanatory role in accounting for mental states. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 3.8.6) | |
| A reaction: Colour and shape are not totally unrelated, as they can both be totally explained by a full knowledge of the physical substance involved. ...But maybe if we fully understood Spinoza's single substance...? See Idea 4834. |
| 541 | Virtue comes more from habit than character [Critias] |
| Full Idea: More men are good through habit than through character. | |
| From: Critias (fragments/reports [c.440 BCE], B09), quoted by John Stobaeus - Anthology 3.29.41 |
| 3528 | Causality may require that a law is being followed [Maslin] |
| Full Idea: The principle of nomological causality says that if two events are intrinsically causally related, there must be a strict physical law under which they can be subsumed. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 7.5) |
| 3525 | Strict laws make causation logically necessary [Maslin] |
| Full Idea: 'Deductive-nomological' explanation consists of two premises - a strict law with no exceptions and supporting deterministic counterfactuals, and a statement of an event which falls under the law - which together logically require the effect. | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 7.4) |
| 3527 | Strict laws allow no exceptions and are part of a closed system [Maslin] |
| Full Idea: 'Strict' laws of nature contain no ceteris paribus clauses ('all things being equal'), and are part of a closed system (so that whatever affects the system must be included within the system). | |
| From: Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 7.5) |
| 542 | Fear of the gods was invented to discourage secret sin [Critias] |
| Full Idea: When the laws forbade men to commit open crimes of violence, and they began to do them in secret, a wise and clever man invented fear of the gods for mortals, to frighten the wicked, even if they sin in secret. | |
| From: Critias (fragments/reports [c.440 BCE], B25), quoted by Sextus Empiricus - Against the Professors (six books) 9.54 |