90 ideas
16227 | Philosophers are good at denying the obvious [Hawley] |
15945 | Second-order set theory just adds a version of Replacement that quantifies over functions [Lavine] |
15914 | An 'upper bound' is the greatest member of a subset; there may be several of these, so there is a 'least' one [Lavine] |
15921 | Collections of things can't be too big, but collections by a rule seem unlimited in size [Lavine] |
15937 | Those who reject infinite collections also want to reject the Axiom of Choice [Lavine] |
15936 | The Power Set is just the collection of functions from one collection to another [Lavine] |
15899 | Replacement was immediately accepted, despite having very few implications [Lavine] |
15930 | Foundation says descending chains are of finite length, blocking circularity, or ungrounded sets [Lavine] |
15920 | Pure collections of things obey Choice, but collections defined by a rule may not [Lavine] |
15898 | The controversy was not about the Axiom of Choice, but about functions as arbitrary, or given by rules [Lavine] |
15919 | The 'logical' notion of class has some kind of definition or rule to characterise the class [Lavine] |
15900 | The iterative conception of set wasn't suggested until 1947 [Lavine] |
15931 | The iterative conception needs the Axiom of Infinity, to show how far we can iterate [Lavine] |
15932 | The iterative conception doesn't unify the axioms, and has had little impact on mathematical proofs [Lavine] |
15933 | Limitation of Size: if it's the same size as a set, it's a set; it uses Replacement [Lavine] |
15913 | A collection is 'well-ordered' if there is a least element, and all of its successors can be identified [Lavine] |
15926 | Second-order logic presupposes a set of relations already fixed by the first-order domain [Lavine] |
15934 | Mathematical proof by contradiction needs the law of excluded middle [Lavine] |
16216 | Part of the sense of a proper name is a criterion of the thing's identity [Hawley] |
15907 | Mathematics is nowadays (thanks to set theory) regarded as the study of structure, not of quantity [Lavine] |
15942 | Every rational number, unlike every natural number, is divisible by some other number [Lavine] |
15922 | For the real numbers to form a set, we need the Continuum Hypothesis to be true [Lavine] |
18250 | Cauchy gave a necessary condition for the convergence of a sequence [Lavine] |
15904 | The two sides of the Cut are, roughly, the bounding commensurable ratios [Lavine] |
15912 | Counting results in well-ordering, and well-ordering makes counting possible [Lavine] |
15949 | The theory of infinity must rest on our inability to distinguish between very large sizes [Lavine] |
15947 | The infinite is extrapolation from the experience of indefinitely large size [Lavine] |
15940 | The intuitionist endorses only the potential infinite [Lavine] |
15909 | 'Aleph-0' is cardinality of the naturals, 'aleph-1' the next cardinal, 'aleph-ω' the ω-th cardinal [Lavine] |
15915 | Ordinals are basic to Cantor's transfinite, to count the sets [Lavine] |
15917 | Paradox: the class of all ordinals is well-ordered, so must have an ordinal as type - giving a bigger ordinal [Lavine] |
15918 | Paradox: there is no largest cardinal, but the class of everything seems to be the largest [Lavine] |
15929 | Set theory will found all of mathematics - except for the notion of proof [Lavine] |
15935 | Modern mathematics works up to isomorphism, and doesn't care what things 'really are' [Lavine] |
15928 | Intuitionism rejects set-theory to found mathematics [Lavine] |
16211 | A homogeneous rotating disc should be undetectable according to Humean supervenience [Hawley] |
16219 | Non-linguistic things cannot be indeterminate, because they don't have truth-values at all [Hawley] |
16223 | Maybe for the world to be vague, it must be vague in its foundations? [Hawley] |
16226 | Epistemic vagueness seems right in the case of persons [Hawley] |
16208 | Supervaluation refers to one vaguely specified thing, through satisfaction by everything in some range [Hawley] |
16221 | Supervaluationism takes what the truth-value would have been if indecision was resolved [Hawley] |
16230 | Maybe the only properties are basic ones like charge, mass and spin [Hawley] |
16665 | There are entities, and then positive 'modes', modifying aspects outside the thing's essence [Suárez] |
16666 | A mode determines the state and character of a quantity, without adding to it [Suárez] |
16232 | An object is 'natural' if its stages are linked by certain non-supervenient relations [Hawley] |
16667 | Substances are incomplete unless they have modes [Suárez, by Pasnau] |
16200 | Are sortals spatially maximal - so no cat part is allowed to be a cat? [Hawley] |
16237 | The modal features of statue and lump are disputed; when does it stop being that statue? [Hawley] |
16238 | Perdurantists can adopt counterpart theory, to explain modal differences of identical part-sums [Hawley] |
16220 | Vagueness is either in our knowledge, in our talk, or in reality [Hawley] |
16222 | Indeterminacy in objects and in properties are not distinct cases [Hawley] |
17007 | Forms must rule over faculties and accidents, and are the source of action and unity [Suárez] |
16780 | Partial forms of leaf and fruit are united in the whole form of the tree [Suárez] |
16758 | The best support for substantial forms is the co-ordinated unity of a natural being [Suárez] |
16743 | We can get at the essential nature of 'quantity' by knowing bulk and extension [Suárez] |
16228 | The constitution theory is endurantism plus more than one object in a place [Hawley] |
16229 | Constitution theory needs sortal properties like 'being a sweater' to distinguish it from its thread [Hawley] |
14492 | If the constitution view says thread and sweater are two things, why do we talk of one thing? [Hawley] |
13074 | Only natural kinds and their members have real essences [Suárez, by Cover/O'Leary-Hawthorne] |
16742 | We only know essences through non-essential features, esp. those closest to the essence [Suárez] |
16193 | 'Adverbialism' explains change by saying an object has-at-some-time a given property [Hawley] |
16195 | Presentism solves the change problem: the green banana ceases, so can't 'relate' to the yellow one [Hawley] |
16202 | The problem of change arises if there must be 'identity' of a thing over time [Hawley] |
16192 | Endurance theory can relate properties to times, or timed instantiations to properties [Hawley] |
16196 | Endurance is a sophisticated theory, covering properties, instantiation and time [Hawley] |
16197 | How does perdurance theory explain our concern for our own future selves? [Hawley] |
16191 | Perdurance needs an atemporal perspective, to say that the object 'has' different temporal parts [Hawley] |
16199 | If an object is the sum of all of its temporal parts, its mass is staggeringly large! [Hawley] |
16201 | Perdurance says things are sums of stages; Stage Theory says each stage is the thing [Hawley] |
16240 | If a life is essentially the sum of its temporal parts, it couldn't be shorter or longer than it was? [Hawley] |
16203 | Stage Theory seems to miss out the link between stages of the same object [Hawley] |
16204 | Stage Theory says every stage is a distinct object, which gives too many objects [Hawley] |
16212 | An isolated stage can't be a banana (which involves suitable relations to other stages) [Hawley] |
16213 | Stages of one thing are related by extrinsic counterfactual and causal relations [Hawley] |
16206 | Stages must be as fine-grained in length as change itself, so any change is a new stage [Hawley] |
16205 | The stages of Stage Theory seem too thin to populate the world, or to be referred to [Hawley] |
22143 | Identity does not exclude possible or imagined difference [Suárez, by Boulter] |
22144 | Real Essential distinction: A and B are of different natural kinds [Suárez, by Boulter] |
22146 | Minor Real distinction: B needs A, but A doesn't need B [Suárez, by Boulter] |
22145 | Major Real distinction: A and B have independent existences [Suárez, by Boulter] |
22147 | Conceptual/Mental distinction: one thing can be conceived of in two different ways [Suárez, by Boulter] |
22148 | Modal distinction: A isn't B or its property, but still needs B [Suárez, by Boulter] |
16225 | If two things might be identical, there can't be something true of one and false of the other [Hawley] |
22149 | Scholastics assess possibility by what has actually happened in reality [Suárez, by Boulter] |
16239 | To decide whether something is a counterpart, we need to specify a relevant sortal concept [Hawley] |
16218 | On any theory of self, it is hard to explain why we should care about our future selves [Hawley] |
7563 | The old 'influx' view of causation says it is a flow of accidental properties from A to B [Suárez, by Jolley] |
16215 | Causation is nothing more than the counterfactuals it grounds? [Hawley] |
16207 | Time could be discrete (like integers) or dense (rationals) or continuous (reals) [Hawley] |
16682 | Other things could occupy the same location as an angel [Suárez] |