21 ideas
| 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) |
| 16065 | Constitution is identity (being in the same place), or it isn't (having different possibilities) [Wasserman] |
| Full Idea: Some insist that constitution is identity, on the grounds that distinct material objects cannot occupy the same place at the same time. Others argue that constitution is not identity, since the statue and its material differ in important respects. | |
| From: Ryan Wasserman (Material Constitution [2009], Intro) | |
| A reaction: The 'important respects' seem to concern possibilities rather than actualities, which is suspicious. It is misleading to think we are dealing with two things and their relation here. Objects must have constitutions; constitutions make objects. |
| 16067 | Constitution is not identity, because it is an asymmetric dependence relation [Wasserman] |
| Full Idea: For those for whom 'constitution is not identity' (the 'constitution view'), constitution is said to be an asymmetric relation, and also a dependence relation (unlike identity). | |
| From: Ryan Wasserman (Material Constitution [2009], 2) | |
| A reaction: It seems obvious that constitution is not identity, because there is more to a thing's identity than its mere constitution. But this idea makes it sound as if constitution has nothing to do with identity (chalk and cheese), and that can't be right. |
| 16069 | There are three main objections to seeing constitution as different from identity [Wasserman] |
| Full Idea: The three most common objections to the constitution view are the Impenetrability Objection (two things in one place?), the Extensionality Objection (mereology says wholes are just their parts), and the Grounding Objection (their ground is the same). | |
| From: Ryan Wasserman (Material Constitution [2009], 2) | |
| A reaction: [summary] He adds a fourth, that if two things can be in one place, why stop at two? [Among defenders of the Constitution View he lists Baker, Fine, Forbes, Koslicki, Kripke, Lowe, Oderberg, N.Salmon, Shoemaker, Simons and Yablo.] |
| 16068 | The weight of a wall is not the weight of its parts, since that would involve double-counting [Wasserman] |
| Full Idea: We do not calculate the weight of something by summing the weights of all its parts - weigh bricks and the molecules of a wall and you will get the wrong result, since you have weighed some parts more than once. | |
| From: Ryan Wasserman (Material Constitution [2009], 2) | |
| A reaction: In fact the complete inventory of the parts of a thing is irrelevant to almost anything we would like to know about the thing. The parts must be counted at some 'level' of division into parts. An element can belong to many different sets. |
| 16074 | Relative identity may reject transitivity, but that suggests that it isn't about 'identity' [Wasserman] |
| Full Idea: If the relative identity theorist denies transitivity (to deal with the Ship of Theseus, for example), this would make us suspect that relativised identity relations are not identity relations, since transitivity seems central to identity. | |
| From: Ryan Wasserman (Material Constitution [2009], 6) | |
| A reaction: The problem here, I think, focuses on the meaning of the word 'same'. One change of plank leaves you with the same ship, but that is not transitive. If 'identical' is too pure to give the meaning of 'the same' it's not much use in discussing the world. |
| 2705 | How can intuitionists distinguish universal convictions from local cultural ones? [Hare] |
| Full Idea: There are convictions which are common to most societies; but there are others which are not, and no way is given by intuitionists of telling which are the authoritative data. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.454) | |
| A reaction: It seems unfair on intuitionists to say they haven't given a way to evaluate such things, given that they have offered intuition. The issue is what exactly they mean by 'intuition'. |
| 2712 | You can't use intuitions to decide which intuitions you should cultivate [Hare] |
| Full Idea: If it comes to deciding what intuitions and dispositions to cultivate, we cannot rely on the intuitions themselves, as intuitionists do. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.461) | |
| A reaction: Makes intuitionists sound a bit dim. Surely Hume identifies dispositions (such as benevolence) which should be cultivated, because they self-evidently improve social life? |
| 2706 | Emotivists mistakenly think all disagreements are about facts, and so there are no moral reasons [Hare] |
| Full Idea: Emotivists concluded too hastily that because naturalism and intuitionism are false, you cannot reason about moral questions, because they assumed that the only questions you can reason about are factual ones. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.455) | |
| A reaction: Personally I have a naturalistic view of ethics (based on successful functioning, as indicated by Aristotle), so not my prob. Why can't we reason about expressive emotions? We reason about art. |
| 2709 | Prescriptivism sees 'ought' statements as imperatives which are universalisable [Hare] |
| Full Idea: Universal prescriptivists hold that 'ought'-judgements are prescriptive like plain imperatives, but differ from them in being universalisable. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.457) | |
| A reaction: Sounds a bit tautological. Which comes first, the normativity or the universalisability? |
| 2704 | If morality is just a natural or intuitive description, that leads to relativism [Hare] |
| Full Idea: Non-descriptivists (e.g. prescriptivists) reject descriptivism in its naturalist or intuitionist form, because they are both destined to collapse into relativism. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.453) | |
| A reaction: I'm not clear from this why prescriptism would not also turn out to be relativist, if it includes evaluations along with facts. |
| 2703 | Descriptivism say ethical meaning is just truth-conditions; prescriptivism adds an evaluation [Hare] |
| Full Idea: Ethical descriptivism is the view that ethical sentence-meaning is wholly determined by truth-conditions. …Prescriptivists think there is a further element of meaning, which expresses prescriptions or evaluations or attitudes which we assent to. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.452) | |
| A reaction: Not sure I understand either of these. If all meaning consists of truth-conditions, that will apply to ethics. If meaning includes evaluations, that will apply to non-ethics. |
| 2707 | If there can be contradictory prescriptions, then reasoning must be involved [Hare] |
| Full Idea: Prescriptivists claim that there are rules of reasoning which govern non-descriptive as well as descriptive speech acts. The standard example is possible logical inconsistency between contradictory prescriptions. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.455) | |
| A reaction: The example doesn't seem very good. Inconsistency can appear in any area of thought, but that isn't enough to infer full 'rules of reasoning'. I could desire two incompatible crazy things. |
| 2708 | An 'ought' statement implies universal application [Hare] |
| Full Idea: In any 'ought' statement there is implicit a principle which says that the statement applies to all precisely similar situations. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.456) | |
| A reaction: No two situations can ever be 'precisely' similar. Indeed, 'precisely similar' may be an oxymoron (at least for situations). Kantians presumably like this idea. |
| 2711 | Prescriptivism implies a commitment, but descriptivism doesn't [Hare] |
| Full Idea: Prescriptivists hold that moral judgements commit the speaker to motivations and actions, but non-moral facts by themselves do not do this. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.459) | |
| A reaction: Surely hunger motivates to action? I suppose the key word is 'commit'. But lazy people are allowed to make moral judgements. |
| 2710 | Moral judgements must invoke some sort of principle [Hare] |
| Full Idea: To make moral judgements is implicitly to invoke some principle, however specific. | |
| From: Richard M. Hare (Universal Prescriptivism [1991], p.458) |