16 ideas
| 22462 | We should speak the truth, but also preserve and pursue it [Foot] |
| Full Idea: There belongs to truthfulness not only the avoidance of lying but also that other kind of attachment to truth which has to do with its preservation and pursuit. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.74) | |
| A reaction: This is truth as a value, rather than as a mere phenomenon of accurate thought and speech. The importance of 'preserving' the truth is the less common part of this idea. |
| 13201 | ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton] |
| Full Idea: To know if A ∈ B, we look at the set A as a single object, and check if it is among B's members. But if we want to know whether A ⊆ B then we must open up set A and check whether its various members are among the members of B. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 1:04) | |
| A reaction: This idea is one of the key ideas to grasp if you are going to get the hang of set theory. John ∈ USA ∈ UN, but John is not a member of the UN, because he isn't a country. See Idea 12337 for a special case. |
| 13204 | The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton] |
| Full Idea: The 'ordered pair' <x,y> is defined to be {{x}, {x,y}}; hence it can be proved that <u,v> = <x,y> iff u = x and v = y (given by Kuratowski in 1921). ...The definition is somewhat arbitrary, and others could be used. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 3:36) | |
| A reaction: This looks to me like one of those regular cases where the formal definitions capture all the logical behaviour of the concept that are required for inference, while failing to fully capture the concept for ordinary conversation. |
| 13206 | A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton] |
| Full Idea: A 'linear ordering' (or 'total ordering') on A is a binary relation R meeting two conditions: R is transitive (of xRy and yRz, the xRz), and R satisfies trichotomy (either xRy or x=y or yRx). | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 3:62) |
| 13200 | Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton] |
| Full Idea: Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ. A man with an empty container is better off than a man with nothing. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 1.03) |
| 13199 | The empty set may look pointless, but many sets can be constructed from it [Enderton] |
| Full Idea: It might be thought at first that the empty set would be a rather useless or even frivolous set to mention, but from the empty set by various set-theoretic operations a surprising array of sets will be constructed. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 1:02) | |
| A reaction: This nicely sums up the ontological commitments of mathematics - that we will accept absolutely anything, as long as we can have some fun with it. Sets are an abstraction from reality, and the empty set is the very idea of that abstraction. |
| 13203 | The singleton is defined using the pairing axiom (as {x,x}) [Enderton] |
| Full Idea: Given any x we have the singleton {x}, which is defined by the pairing axiom to be {x,x}. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 2:19) | |
| A reaction: An interesting contrivance which is obviously aimed at keeping the axioms to a minimum. If you can do it intuitively with a new axiom, or unintuitively with an existing axiom - prefer the latter! |
| 13202 | Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton] |
| Full Idea: It was observed by several people that for a satisfactory theory of ordinal numbers, Zermelo's axioms required strengthening. The Axiom of Replacement was proposed by Fraenkel and others, giving rise to the Zermelo-Fraenkel (ZF) axioms. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 1:15) |
| 13205 | We can only define functions if Choice tells us which items are involved [Enderton] |
| Full Idea: For functions, we know that for any y there exists an appropriate x, but we can't yet form a function H, as we have no way of defining one particular choice of x. Hence we need the axiom of choice. | |
| From: Herbert B. Enderton (Elements of Set Theory [1977], 3:48) |
| 22458 | Consequentialists can hurt the innocent in order to prevent further wickedness [Foot] |
| Full Idea: For consequentialists there will be nothing that it will not be right to do to a perfectly innocent individual, if that is the only way of preventing another agent from doing more things of the same kind. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.61) | |
| A reaction: This is her generalised version that Williams dramatised as Jim and the Indians. Roughly, if you achieve a good outcome, it matters little how it is achieved. Foot sees consequentialism as the main problem with utilitarianism. |
| 22460 | Why might we think that a state of affairs can be morally good or bad? [Foot] |
| Full Idea: We should ask why we think that it makes sense to talk about morally good and bad states of affairs. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.68) | |
| A reaction: This is the key question in her attack on consequentialism. There is nothing 'morally' good about my football team winning a great victory. |
| 22461 | Good outcomes are not external guides to morality, but a part of virtuous actions [Foot] |
| Full Idea: It is not that maximum welfare or 'the best outcome' stands outside morality as it foundation and arbiter, but rather that it appears within morality as the end of one of the virtues. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.73) | |
| A reaction: She cites justice and benevolence as aiming at different (and even conflicting) outcomes. I'm not sure about her distinction between 'outside' and 'within' morality. I suppose a virtuously created end is a moral end, unlike mere good states of affairs. |
| 22464 | The idea of a good state of affairs has no role in the thought of Aristotle, Rawls or Scanlon [Foot] |
| Full Idea: The idea of the goodness of total states of affairs played no part in Aristotle's moral philosophy, and in modern times plays not part either in Rawls's account of justice or in the theories of more thoroughgoing contractualists such as Scanlon. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.76) | |
| A reaction: We can add Kant to that. But if the supremely good state of affairs were permanently achieved, would that make morality irrelevant? A community of the exceptionally virtuous would not need the veil of ignorance, or contracts. |
| 7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |
| Full Idea: The six perfections are of giving, morality, patience, vigour, meditation, and wisdom. | |
| From: Nagarjuna (Mahaprajnaparamitashastra [c.120], 88) | |
| A reaction: What is 'morality', if giving is not part of it? I like patience and vigour being two of the virtues, which immediately implies an Aristotelian mean (which is always what is 'appropriate'). |
| 22463 | Morality is seen as tacit legislation by the community [Foot] |
| Full Idea: Morality is thought of as a kind of tacit legislation by the community. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.75) | |
| A reaction: Foot presents this as a utilitarian doctrine, because the tacit legislation is felt to produce the best outcomes. This is Nietzsche's good and evil, beyond which he wished to go (presumably following other values). |
| 22459 | For consequentialism, it is irrational to follow a rule which in this instance ends badly [Foot] |
| Full Idea: It would be irrational to obey even the most useful rule if in a particular instance we clearly see that such obedience will not have the best results. | |
| From: Philippa Foot (Utilitarianism and the Virtues [1985], p.62) | |
| A reaction: This is the simple reason why attempts at rule utilitarianism always lead back to act utilitarianism. Another way of putting it is that a good rule can only be assessed by the outcomes of individual acts that follow it. |